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The TI-99/4 and TI-99/4A are
home computer Home computers were a class of microcomputers that entered the market in 1977 and became common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a s ...
s released by
Texas Instruments Texas Instruments Incorporated (TI) is an American multinational semiconductor company headquartered in Dallas, Texas. It is one of the top 10 semiconductor companies worldwide based on sales volume. The company's focus is on developing analog ...
(TI) in 1979 and 1981, respectively. Based on TI's own
TMS9900 The TMS9900 was one of the first commercially available single-chip 16-bit microprocessors. Introduced in June 1976, it implemented Texas Instruments's TI-990 minicomputer architecture in a single-chip format, and was initially used for low-end ...
microprocessor A microprocessor is a computer processor (computing), processor for which the data processing logic and control is included on a single integrated circuit (IC), or a small number of ICs. The microprocessor contains the arithmetic, logic, a ...
originally used in
minicomputer A minicomputer, or colloquially mini, is a type of general-purpose computer mostly developed from the mid-1960s, built significantly smaller and sold at a much lower price than mainframe computers . By 21st century-standards however, a mini is ...
s, the TI-99/4 was the first
16-bit 16-bit microcomputers are microcomputers that use 16-bit microprocessors. A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two ...
home computer. The associated
TMS9918 IMAGE:TMS9918A 01.jpg, VDP TMS9918A IMAGE:TMS9918A 02.jpg, VDP TMS9918A The TMS9918 is a video display controller (VDC) manufactured by Texas Instruments, in manuals referenced as "Video Display Processor" (VDP) and introduced in 1979. The TMS9918 ...
video display controller A video display controller (VDC), also called a display engine or display interface, is an integrated circuit which is the main component in a video-signal generator, a device responsible for the production of a TV video signal in a computing ...
provides color graphics and sprite support which were only comparable with those of the Atari 400 and 800 released a month later. The TI-99 series also initially competed with the
Apple II Apple II ("apple Roman numerals, two", stylized as Apple ][) is a series of microcomputers manufactured by Apple Computer, Inc. from 1977 to 1993. The Apple II (original), original Apple II model, which gave the series its name, was designed ...
and
TRS-80 The TRS-80 Micro Computer System (TRS-80, later renamed the Model I to distinguish it from successors) is a desktop microcomputer developed by American company Tandy Corporation and sold through their Radio Shack stores. Launched in 1977, it is ...
."Death of a Computer,"
April 1984, ''
Texas Monthly ''Texas Monthly'' (stylized as ''TexasMonthly'') is a monthly American magazine headquartered in Downtown Austin, Texas. Founded in 1973 by Michael R. Levy, ''Texas Monthly'' chronicles life in contemporary Texas, writing on politics, the Natura ...
,'' retrieved September 20, 2023
The calculator-style keyboard of the TI-99/4 and the high price were cited as weak points. TI's reliance on
ROM cartridge A ROM cartridge, usually referred to in context simply as a cartridge, cart, cassette, or card, is a replaceable part designed to be connected to a consumer electronics device such as a home computer, video game console or, to a lesser extent, ...
s and their practice of limiting developer information to select third parties resulted in a lack of software for the system. The TI-99/4A was released in June 1981 with a simplified internal design, full-travel keyboard, improved graphics, and a unique expansion system. At half the price of the original model, sales picked up significantly and TI supported the 4A with peripherals, including a
speech synthesizer Speech synthesis is the artificial production of human speech. A computer system used for this purpose is called a speech synthesizer, and can be implemented in software or Computer hardware, hardware products. A text-to-speech (TTS) system conv ...
and a "Peripheral Expansion System" box to contain hardware add-ons. TI released developer information and tools, but the insistence on remaining sole publisher continued to starve the platform of software. Architectural quirks of both models reduced the performance benefits of the 16-bit CPU. The 1981 US launch of the TI-99/4A followed
Commodore Commodore may refer to: Ranks * Commodore (rank), a naval rank ** Commodore (Royal Navy), in the United Kingdom ** Commodore (India), in India ** Commodore (United States) ** Commodore (Canada) ** Commodore (Finland) ** Commodore (Germany) or ' ...
's
VIC-20 The VIC-20 (known as the VC-20 in Germany and the VIC-1001 in Japan) is an 8-bit entry level home computer that was sold by Commodore International, Commodore Business Machines. The VIC-20 was announced in 1980, roughly three years after Commod ...
by several months. Commodore CEO
Jack Tramiel Jack Tramiel (, ); born Idek Trzmiel (; December 13, 1928 – April 8, 2012) was a Polish- American businessman and Holocaust survivor, best known for founding Commodore International. The Commodore PET, VIC-20, and Commodore 64 are som ...
began a
price war A price war is a form of market competition in which companies within an industry engage in aggressive pricing activity "characterized by the repeated cutting of prices below those of competitors". This leads to a cycle, where each competitor att ...
by repeatedly lowering the price of the VIC-20 and forcing TI to do the same. In late 1982, TI was shipping 5,000 computers a day from their factory in
Lubbock, Texas Lubbock ( ) is a city in the U.S. state of Texas and the county seat of Lubbock County. With a population of 272,086 in 2024, Lubbock is the 10th-most populous city in Texas and the 84th-most populous in the United States. The city is in the ...
. By 1983, the 99/4A was selling at a loss for under . Even with the increased user base created by the heavy discounts, TI lost US$330 million in the third quarter of 1983 and announced the discontinuation of the TI-99/4A in October 1983. Production ended in March 1984. The TI-99/4 was intended to fit in the middle of a planned range of TI-99 computers, none of which were released, but prototypes and documentation have been found after the TI-99/4A was discontinued.


Features

Developed by
Texas Instruments Texas Instruments Incorporated (TI) is an American multinational semiconductor company headquartered in Dallas, Texas. It is one of the top 10 semiconductor companies worldwide based on sales volume. The company's focus is on developing analog ...
(TI), the TI-99/4A is a self-contained console with the
motherboard A motherboard, also called a mainboard, a system board, a logic board, and informally a mobo (see #Nomenclature, "Nomenclature" section), is the main printed circuit board (PCB) in general-purpose computers and other expandable systems. It ho ...
,
ROM cartridge A ROM cartridge, usually referred to in context simply as a cartridge, cart, cassette, or card, is a replaceable part designed to be connected to a consumer electronics device such as a home computer, video game console or, to a lesser extent, ...
slot, and full-travel keyboard in the same case. The power supply is external. An
RF modulator An RF modulator (radio frequency modulator) is an electronic device used to convert signals from devices such as media players, VCRs and game consoles to a format that can be handled by a device designed to receive a modulated RF input, such ...
allows the use of a television as a monitor. Lowercase letters are displayed as
small caps In typography, small caps (short for small capitals) are grapheme, characters typeset with glyphs that resemble uppercase letters but reduced in height and weight close to the surrounding lowercase letters or text figures. Small caps are used i ...
, rather than separate glyphs.
TI BASIC TI-BASIC is the official name of a BASIC-like language built into Texas Instruments' graphing calculators. TI-BASIC is a language family of three different and incompatible versions, released on different products: * TI-BASIC 83 (on Z80 processo ...
, an
ANSI The American National Standards Institute (ANSI ) is a private nonprofit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organiz ...
-compliant
BASIC Basic or BASIC may refer to: Science and technology * BASIC, a computer programming language * Basic (chemistry), having the properties of a base * Basic access authentication, in HTTP Entertainment * Basic (film), ''Basic'' (film), a 2003 film ...
interpreter based on
Dartmouth BASIC Dartmouth BASIC is the original version of the BASIC programming language. It was designed by two professors at Dartmouth College, John G. Kemeny and Thomas E. Kurtz. With the underlying Dartmouth Time-Sharing System (DTSS), it offered an interac ...
, is built-in and includes support for graphics, sound, and file system access. Later versions of the 99/4A, identified by (C)1983 TEXAS INSTRUMENTS V2.2 on the title page, prevent the use of unlicensed
ROM Rom, or ROM may refer to: Biomechanics and medicine * Risk of mortality, a medical classification to estimate the likelihood of death for a patient * Rupture of membranes, a term used during pregnancy to describe a rupture of the amniotic sac * ...
cartridges from third-party manufacturers such as
Atarisoft Atarisoft was a brand name used by Atari, Inc. in 1983 and 1984 to publish video games for non-Atari home computers and consoles. Each platform had a specific color for its game packages: video games sold for the Commodore 64 were in green boxes ...
. Both TI-99/4 models use the
16-bit 16-bit microcomputers are microcomputers that use 16-bit microprocessors. A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two ...
TMS9900 The TMS9900 was one of the first commercially available single-chip 16-bit microprocessors. Introduced in June 1976, it implemented Texas Instruments's TI-990 minicomputer architecture in a single-chip format, and was initially used for low-end ...
CPU A central processing unit (CPU), also called a central processor, main processor, or just processor, is the primary processor in a given computer. Its electronic circuitry executes instructions of a computer program, such as arithmetic, log ...
running at 3
MHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base u ...
. The TMS9900 is a single-chip implementation of a
TI-990 The TI-990 was a series of 16-bit minicomputers sold by Texas Instruments (TI) in the 1970s and 1980s. It served as a replacement for TI's earlier minicomputer systems, the TI-960 and the TI-980. The TI-990 featured several unique innovations and ...
minicomputer. Although a full 16-bit processor, only the system ROM and 256 bytes of scratchpad RAM are available on the 16-bit bus. Peripherals include a 5¼"
floppy disk drive A floppy disk or floppy diskette (casually referred to as a floppy, a diskette, or a disk) is a type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined with a ...
and controller, an
RS-232 In telecommunications, RS-232 or Recommended Standard 232 is a standard introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' (''data terminal equipment'') such as a compu ...
card with two serial ports and one parallel port, a
P-code Bytecode (also called portable code or p-code) is a form of instruction set designed for efficient execution by a software interpreter. Unlike human-readable source code, bytecodes are compact numeric codes, constants, and references (normal ...
card for Pascal support, a
thermal printer Thermal printing (or direct thermal printing) is a digital printing process which produces a printed image by passing paper with a thermochromic coating, commonly known as thermal paper, over a print head consisting of tiny electrically hea ...
, a 300-
baud In telecommunications and electronics, baud (; symbol: Bd) is a common unit of measurement of symbol rate, which is one of the components that determine the speed of communication over a data channel. It is the unit for symbol rate or modulat ...
acoustic coupler In telecommunications, an acoustic coupler is an interface device for coupling electrical signals by acoustical means—usually into and out of a telephone. The link is achieved through converting electric signals from the phone line to so ...
, a
tape drive A tape drive is a data storage device that reads and writes data on a magnetic tape. Magnetic-tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and long archival stability. ...
using standard audio cassettes as media, and a 32 KB memory
expansion card In computing, an expansion card (also called an expansion board, adapter card, peripheral card or accessory card) is a printed circuit board that can be inserted into an electrical connector, or expansion slot (also referred to as a bus sl ...
.


Video display processor

Graphics in the 99/4A are generated by a
TMS9918A VDP TMS9918A VDP TMS9918A The TMS9918 is a video display controller (VDC) manufactured by Texas Instruments, in manuals referenced as "Video Display Processor" (VDP) and introduced in 1979. The TMS9918 and its variants were used in the Casio PV ...
Video Display Processor (VDP), with a variant for PAL territories. The VDP was developed by TI and also sold independently, allowing it to be used in other systems. It serves as the video processor for the
ColecoVision ColecoVision is a second-generation home video-game console developed by Coleco and launched in North America in August 1982. It was released a year later in Europe by CBS Electronics as the CBS ColecoVision. The console offered a closer expe ...
and
SG-1000 The is a home video game console manufactured by Sega. It was Sega's first entry into the home video game hardware business. Developed in response to a downturn in arcades starting in 1982, the SG-1000 was created on the advice of Hayao Nak ...
consoles, and an earlier model is part of the
MSX MSX is a standardized home computer architecture, announced by ASCII Corporation on June 16, 1983. It was initially conceived by Microsoft as a product for the Eastern sector, and jointly marketed by Kazuhiko Nishi, the director at ASCII Corpo ...
computer standard. The TMS9918A supports character-based and
bitmap In computing, a bitmap (also called raster) graphic is an image formed from rows of different colored pixels. A GIF is an example of a graphics image file that uses a bitmap. As a noun, the term "bitmap" is very often used to refer to a partic ...
display modes as well as hardware sprites. There are 32 single-color sprites total, but only a maximum of four can be displayed per
scan line A scan line (also scanline) is one line, or row, in a raster scanning pattern, such as a line of video on a cathode-ray tube (CRT) display of a television set or computer monitor. On CRT screens the horizontal scan lines are visually discernib ...
. Each sprite is either 8×8 or 16×16 pixels and can be scaled 2× to 16×16 or 32×32. 16 KB of RAM is provided for the Video Display Processor. VDP RAM is the largest block of writeable memory in the unexpanded TI-99/4A architecture, and is used for storing disk I/O buffers and
TI BASIC TI-BASIC is the official name of a BASIC-like language built into Texas Instruments' graphing calculators. TI-BASIC is a language family of three different and incompatible versions, released on different products: * TI-BASIC 83 (on Z80 processo ...
user programs. Access to this memory has to use the VDP as an intermediary.


Expansion

TI-99 peripherals contain
device driver In the context of an operating system, a device driver is a computer program that operates or controls a particular type of device that is attached to a computer or automaton. A driver provides a software interface to hardware devices, enabli ...
s in ROMs in the hardware. When a new peripheral is attached, it is immediately available for any software that wants to use it. All device access uses a generic file-based I/O mechanism, allowing new devices to be added without updating software. The Peripheral Expansion System can hold two RS-232 cards, for a total of four RS-232 ports and two parallel printer ports. The computer supports two cassette drives through a dedicated port, using a custom data format.
Composite video Composite video, also known as CVBS (composite video baseband signal or color, video, blanking and sync), is an analog video format that combines image information—such as brightness (luminance), color (chrominance), and synchronization, int ...
and audio are output through another port on
NTSC NTSC (from National Television System Committee) is the first American standard for analog television, published and adopted in 1941. In 1961, it was assigned the designation System M. It is also known as EIA standard 170. In 1953, a second ...
-based machines, and combine through an external RF modulator for use with a television.
PAL Phase Alternating Line (PAL) is a color encoding system for analog television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 ...
-based machines output a more complex YUV signal which is also modulated to
UHF Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter ...
externally. Two digital
joystick A joystick, sometimes called a flight stick, is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling. Also known as the control column, it is the principal control devic ...
s can be connected through a single
DE-9 The D-subminiature or D-sub is a common type of electrical connector. They are named for their characteristic D-shaped metal shield. When they were introduced, D-subs were among the smallest connectors used on computer systems. Description, ...
port. It is identical to the
Atari joystick port The Atari joystick port is a computer port used to connect various gaming controllers to game console and home computer systems in the 1970s to the 1990s. It was originally introduced on the Atari 2600 in 1977 and then used on the Atari 400 and ...
, but with incompatible pins. Aftermarket adapters allow the use of Atari compatible joysticks. TI sold an official 32 KB RAM expansion. The memory is not available to all uses. For example, an Extended Basic program is restricted to using 24 KB with the remaining 8 KB available for
machine code In computer programming, machine code is computer code consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). For conventional binary computers, machine code is the binaryOn nonb ...
routines. The Mini Memory plug-in module contains 4 KB of battery-backed RAM that can be used as a persistent
RAM disk A RAM drive (also called a RAM disk) is a block of random-access memory ( primary storage or volatile memory) that a computer's software is treating as if the memory were a disk drive (secondary storage). RAM drives provide high-performance te ...
or to load a machine-code program.


Peripheral Expansion Box

The TI-99/4A can be upgraded via expansion cards added to an eight-slot, external chassis containing its own linear power supply and a full-height 5¼" floppy bay. Encased in silver plastic, but made from
sheet steel Sheet metal is metal formed into thin, flat pieces, usually by an industrial process. Thicknesses can vary significantly; extremely thin sheets are considered foil or leaf, and pieces thicker than 6 mm (0.25 in) are considered plate, ...
, this is labeled as the Peripheral Expansion System by TI, but usually called the Peripheral Expansion Box or PEB. Each card has an
LED A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (corresp ...
that blinks or flickers when being accessed by software. The section of the power supply that powers the card slots is unregulated. Each card has on-board regulators for its own requirements, which reduces power consumption on a partially-loaded PEB and allows for cards with unusual voltage requirements. The PEB carries an analog sound input on the expansion bus, allowing the Speech Synthesizer's audio to be carried through the console to the monitor. The audio is also carried through the
ribbon cable A ribbon cable is a cable with many conducting wires running parallel to each other on the same flat plane. As a result, the cable is wide and flat. Its name comes from its resemblance to a piece of ribbon. Ribbon cables are usually seen fo ...
to the PEB, both allowing the relocation of the Speech Synthesizer to the PEB and the possibility of audio cards offering more features than the console's built-in sound. No official cards from TI do this. Official cards from TI that were released and could be placed inside the PEB include * 32 KB RAM expansion card * RS-232 and parallel port card * P-code card, implementing the UCSD p-system IV.0 by acting as a ROM-disk * Diskette drive control card. The design allowed controlling both drives internally in the PEB and external drives. Peripherals designed to be used without the PEB existed too.


Speech synthesizer

In the late 1970s and early 1980s, TI was a pioneer in
speech synthesis Speech synthesis is the artificial production of human speech. A computer system used for this purpose is called a speech synthesizer, and can be implemented in software or hardware products. A text-to-speech (TTS) system converts normal langua ...
because of its LPC Speech Chips which were used in its Speak & Spell toys. A plug-in speech synthesizer module was available for the TI-99/4 and 4A. Speech synthesizers were offered free with the purchase of a number of cartridges and were used by video games such as '' Alpiner'' and ''Parsec''. ''Alpiner''s speech includes male and female voices and can be sarcastic when the player makes a bad move. The synthesizer uses a variant of
linear predictive coding Linear predictive coding (LPC) is a method used mostly in audio signal processing and speech processing for representing the spectral envelope of a digital signal of speech in compressed form, using the information of a linear predictive model ...
and has a small in-built vocabulary. The original intent was to release small cartridges that plugged directly into the synthesizer unit to increase the device's vocabulary. However, the success of software
text-to-speech Speech synthesis is the artificial production of human speech. A computer system used for this purpose is called a speech synthesizer, and can be implemented in software or Computer hardware, hardware products. A text-to-speech (TTS) system conv ...
in the Terminal Emulator II cartridge cancelled that plan.


History

In the late 1970s, TI was a successful manufacturer of large computers and the largest
semiconductor A semiconductor is a material with electrical conductivity between that of a conductor and an insulator. Its conductivity can be modified by adding impurities (" doping") to its crystal structure. When two regions with different doping level ...
manufacturer in the world. In 1977, groups within TI were designing a
video game console A video game console is an electronic device that Input/output, outputs a video signal or image to display a video game that can typically be played with a game controller. These may be home video game console, home consoles, which are generally ...
, a home computer to compete against the TRS-80 and Apple II, and a high-end business personal computer with a
hard drive A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating hard disk drive platter, pla ...
. The first two groups were both working at TI's consumer products division in
Lubbock, Texas Lubbock ( ) is a city in the U.S. state of Texas and the county seat of Lubbock County. With a population of 272,086 in 2024, Lubbock is the 10th-most populous city in Texas and the 84th-most populous in the United States. The city is in the ...
, and continually competed. According to Wally Rhines, the 99/4's "ultracheap keyboard" (with calculator-style keys),
RF modulator An RF modulator (radio frequency modulator) is an electronic device used to convert signals from devices such as media players, VCRs and game consoles to a format that can be handled by a device designed to receive a modulated RF input, such ...
, and ROM cartridges came from the console design. The Lubbock teams were merged and directed towards the home computer market. Others within the company persuaded the Lubbock group to use TI's TMS9900 CPU. This was in keeping with TI's "one company, one computer architecture" concept, where a single processor model would scale from consoles to its high-end minicomputers. The TMS9900 is a single-chip implementation of TI's 16-bit
TI-990 The TI-990 was a series of 16-bit minicomputers sold by Texas Instruments (TI) in the 1970s and 1980s. It served as a replacement for TI's earlier minicomputer systems, the TI-960 and the TI-980. The TI-990 featured several unique innovations and ...
minicomputer, and is the CPU in low-end models of that platform. Feature-limited single-chip versions of popular minicomputer designs from the 1960s were popular in the mid-1970s and newly designed 16-bit and
32-bit In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in a maximum of 32- bit units. Compared to smaller bit widths, 32-bit computers can perform la ...
CPUs like the
Intel 8088 The Intel 8088 ("''eighty-eighty-eight''", also called iAPX 88) microprocessor is a variant of the Intel 8086. Introduced on June 1, 1979, the 8088 has an eight-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers ...
and
Motorola 68000 The Motorola 68000 (sometimes shortened to Motorola 68k or m68k and usually pronounced "sixty-eight-thousand") is a 16/32-bit complex instruction set computer (CISC) microprocessor, introduced in 1979 by Motorola Semiconductor Products Sector ...
, respectively, quickly rendered these earlier designs obsolete. Many of the TMS9900's quirky features, like
processor register A processor register is a quickly accessible location available to a computer's processor. Registers usually consist of a small amount of fast storage, although some registers have specific hardware functions, and may be read-only or write-onl ...
s in
main memory Computer data storage or digital data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers. The central processin ...
, came from its minicomputer roots where such concepts were more common. The team working on the high-end personal computer was merged into TI's Data Systems Division, which had the TI 990 and various
computer terminal A computer terminal is an electronic or electromechanical hardware device that can be used for entering data into, and transcribing data from, a computer or a computing system. Most early computers only had a front panel to input or display ...
s; the division ended the personal computer because it was a threat to the minicomputer. TI's European headquarters worked on another home computer, where a third party consulting firm was contracted to produce a prototype codenamed "Mojo". This was based on TI's version of the
8-bit In computer architecture, 8-bit integers or other data units are those that are 8 bits wide (1 octet). Also, 8-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers or data bu ...
Intel 8080 The Intel 8080 is Intel's second 8-bit computing, 8-bit microprocessor. Introduced in April 1974, the 8080 was an enhanced successor to the earlier Intel 8008 microprocessor, although without binary compatibility.'' Electronic News'' was a week ...
supported by an all-TI chip set. After a series of discussions, Mojo was abandoned and the Consumer Products concept moved forward.


99/4

TI's catalog included a huge variety of analog and digital integrated circuits already widely used in
microcomputer A microcomputer is a small, relatively inexpensive computer having a central processing unit (CPU) made out of a microprocessor. The computer also includes memory and input/output (I/O) circuitry together mounted on a printed circuit board (P ...
s, giving it a single-source advantage no other company could meet. TI used this position to take over markets, as it did in the mid-1970s introducing its first
scientific calculator A scientific calculator is an Electronics, electronic calculator, either desktop or handheld, designed to perform calculations using basic (addition, subtraction, multiplication, Division (mathematics), division) and advanced (Trigonometric fun ...
s. These underpriced its former customers like
Commodore Commodore may refer to: Ranks * Commodore (rank), a naval rank ** Commodore (Royal Navy), in the United Kingdom ** Commodore (India), in India ** Commodore (United States) ** Commodore (Canada) ** Commodore (Finland) ** Commodore (Germany) or ' ...
and drove them out of the calculator business. Observers expected TI would do the same to the microcomputer market if it released a competitive system. ''
The New York Times ''The New York Times'' (''NYT'') is an American daily newspaper based in New York City. ''The New York Times'' covers domestic, national, and international news, and publishes opinion pieces, investigative reports, and reviews. As one of ...
'' suggested that the entry of TI and
Hewlett-Packard The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company. It was founded by Bill Hewlett and David Packard in 1939 in a one-car garage in Palo Alto, California ...
would reshape the entire industry. Through the development period, several companies attempting to enter the home computer market were faced with significant pushback from the
Federal Communications Commission The Federal Communications Commission (FCC) is an independent agency of the United States government that regulates communications by radio, television, wire, internet, wi-fi, satellite, and cable across the United States. The FCC maintains j ...
(FCC). The FCC had developed new rules for consumer devices that connected directly to
television Television (TV) is a telecommunication medium for transmitting moving images and sound. Additionally, the term can refer to a physical television set rather than the medium of transmission. Television is a mass medium for advertising, ...
s in an effort to control ongoing complaints about interference by poorly shielded devices. Televisions of the era generally had only a single antenna input, and thus connecting to them required the internal video signal of the device to be converted to
radio frequency Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the u ...
using an
RF modulator An RF modulator (radio frequency modulator) is an electronic device used to convert signals from devices such as media players, VCRs and game consoles to a format that can be handled by a device designed to receive a modulated RF input, such ...
. If these were poorly shielded the signal would leak out and could be picked up in the antennas of nearby televisions. The new rules were extremely stringent and difficult to meet. TI continued battling the FCC both in the lab and in Congress, where it had considerable power due to its position within Texas's high-tech industry. It failed to meet the FCC requirements as the release date approached. The company eventually gave up and bundled a modified
Zenith Electronics Zenith Electronics, LLC, is an American research and development company that develops ATSC and digital rights management technologies. It is owned by the South Korean company LG Electronics. Zenith was previously an American brand of consumer e ...
television with the computer, as a
computer monitor A computer monitor is an output device that displays information in pictorial or textual form. A discrete monitor comprises a electronic visual display, visual display, support electronics, power supply, Housing (engineering), housing, electri ...
, eliminating the need for the RF modulator by connecting directly to the TV's internal circuitry using a
composite video Composite video, also known as CVBS (composite video baseband signal or color, video, blanking and sync), is an analog video format that combines image information—such as brightness (luminance), color (chrominance), and synchronization, int ...
signal. This put the introductory price at . The 99/4 sold poorly. Very little software was available, as few developers ported their products to its 16-bit CPU. The machine was met with almost universal disdain when it was released. Every review complained about the keyboard, the lack of lower case characters, any sort of expansion, and lack of software. In July 1980,
Adam Osborne Adam Osborne (6 March 1939 – 18 March 2003) was a British author, software publisher, and computer designer who founded several companies in the United States and elsewhere. He introduced the Osborne 1, the first commercially successful po ...
reported that, despite poor sales, TI had raised the price of a complete system to , higher than the popular Apple II, which started at . Osborne said, "Some dealers, who have offered the complete system (including the monitor) for less than the price of the Apple, have still been unable to sell it". TI experimented with $200 rebates, and dealers decreased the price to as low as $699 not including rebates, but the company sold fewer than 20,000 computers by summer 1981, less than one tenth Apple or
Radio Shack RadioShack (formerly written as Radio Shack) is an American electronics retailer that was established in 1921 as an amateur radio mail-order business. Its parent company was purchased by Tandy Corporation in 1962, which shifted its focus from ma ...
's volume. Atari, Inc. had an
installed base Installed base of a product is the number of units that are currently in use by customers. It provides a measurement of a company's existing customer base and the extent of their investment in a particular product or technology. In contrast to m ...
of
Atari 8-bit computers The Atari 8-bit computers, formally launched as the Atari Home Computer System, are a series of home computers introduced by Atari, Inc., in 1979 with the Atari 400 and Atari 800. The architecture is designed around the 8-bit MOS Technology 650 ...
more than twice as large.
David H. Ahl David H. Ahl (born May 17, 1939) is an American author who is the founder of ''Creative Computing'' magazine. He is also the author of many how-to books, including ''BASIC Computer Games'', the first computer book to sell more than a million cop ...
described the 99/4 as "vastly overpriced, particularly considering its strange keyboard, non-standard Basic, and lack of software". The ''New York Times'' called it an "embarrassing failure".


99/4A

In May 1981 TI released the 99/4A. With a lower $525 price, the company added a typewriter-style keyboard—keeping the non-standard layout—and more expansion options. The expansion system extends from the right side of the chassis, with modules that can be daisy-chained. There is a practical limitation to this, because each module increases the width of the system. The price was initially , less than half that of the 99/4. TI continued lowering the price through 1981, first to , and then to in early 1982, in competition with Commodore's
VIC-20 The VIC-20 (known as the VC-20 in Germany and the VIC-1001 in Japan) is an 8-bit entry level home computer that was sold by Commodore International, Commodore Business Machines. The VIC-20 was announced in 1980, roughly three years after Commod ...
. This turned into a
price war A price war is a form of market competition in which companies within an industry engage in aggressive pricing activity "characterized by the repeated cutting of prices below those of competitors". This leads to a cycle, where each competitor att ...
with Commodore. TI responded by cutting the wholesale price of the 99 by , while also offering a rebate directly to consumers, lowering the street price to about .
Bill Cosby in advertising American comedian and actor Bill Cosby was a popular spokesperson for advertising from the 1960sbefore his first starring television roleuntil the early 2000s. He started with White Owl cigars, and later endorsed the Jell-O frosty ice pop treats ...
for TI marketed the refund. By mid-1982,
Jerry Pournelle Jerry Eugene Pournelle (; August 7, 1933 – September 8, 2017) was an American scientist in the area of operations research and ergonomics, human factors research, a science fiction writer, essayist, journalist, and one of the first bloggers. ...
wrote that TI was "practically giving away the TI-99/4A". An industry joke stated that the company was losing money on each computer, but was making up for it in volume. Commodore matched the price in December 1982. TI celebrated the 99/4A's market success at the January 1983
Consumer Electronics Show CES (; formerly an initialism for Consumer Electronics Show) is an annual trade show organized by the Consumer Technology Association (CTA). Held in January at the Las Vegas Convention Center in Winchester, Nevada, United States, the event typi ...
in Las Vegas, where Cosby joked how easy it was to sell a computer by paying people to buy one. Sales peaked at 30,000 a week that month, but on 10 January 1983 Commodore lowered the price of its computers. In February TI responded with a 99/4A retail price of . In April, the VIC-20's bundled retail price reached and the 99/4A followed suit. In the spring of 1983, TI attempted to reduce the parts count to maintain a competitive edge by combining multiple chips into a single custom chip, renaming the 4A PCB as a "QI" (Quality Improved) board and began production of plastic beige cases without the former aluminum trim of the black console. In May, it began offering the PEB for free with the purchase of three peripherals. In August the company reduced prices of peripherals by 50% and offered of free software; in September, it reduced software prices by up to 43%. The $100 rebate ended in April 1983, but by then TI had effectively reduced the retail price by that amount; by June the 99/4A sold for as little as $99 in some stores, comparable to the VIC-20's price.


Lack of third-party development

The president of
Spectravideo Spectravideo International Limited (SVI) (printed as Spectra Video, with the space, in game manuals) was an American computer manufacturer and software house. It was originally called SpectraVision, a company founded by Harry Fox in 1981. The ...
later said that "TI got suckered by"
Jack Tramiel Jack Tramiel (, ); born Idek Trzmiel (; December 13, 1928 – April 8, 2012) was a Polish- American businessman and Holocaust survivor, best known for founding Commodore International. The Commodore PET, VIC-20, and Commodore 64 are som ...
, head of Commodore. The company could not make a profit on the TI-99/4A at a price of $99—it was much more expensive to manufacture than the VIC-20—but hoped that selling many inexpensive computers would increase sales of more profitable software and peripherals. Because such a
razor and blades business model The razor and blades business model is a business model in which one item is sold at a low price (or given away) in order to increase sales of a complementary good, such as consumables, consumable supplies. It is different from loss leader, loss l ...
requires that such products be its own, TI strictly controlled development for the computer, discouraging hobbyists and third-party developers. It wanted unsophisticated consumers to buy its computers like an appliance, and not technical users who might want to write their own software, despite the latter being what Pournelle described as "a large unpaid R&D department" for computer companies. The company advertised its calculators in almost every issue of ''BYTE'' starting in 1980, but deliberately excluded its home computer from the ads except briefly in late 1982. TI also used its preexisting calculator sales channel of mass-market retailers, and not specialized computer stores. TI did not provide an editor, assembler, or hardware technical information when it released the computer. Pournelle stated that "TI's message is loud and clear: 'Drop dead, hobbyists!, and added that the company "worked very hard at keeping you outside the machine". Citing ''
Money Money is any item or verifiable record that is generally accepted as payment for goods and services and repayment of debts, such as taxes, in a particular country or socio-economic context. The primary functions which distinguish money are: m ...
'', publisher of ''
Kilobaud Microcomputing ''Kilobaud Microcomputing'' was a magazine dedicated to the computer homebrew hobbyists from 1977 to 1983. It was one of the three influential computer magazines of the 1970s, along with ''BYTE'' and ''Creative Computing''. It focused mostly o ...
''
Wayne Green Wayne Sanger Green II (September 3, 1922 – September 13, 2013) was an American publisher, writer, and consultant. Green was editor of '' CQ'' magazine before he went on to found '' 73'', ''80 Micro'', ''Byte'', '' CD Review'', ''Cold Fusion'', ...
reported in August 1980 that TI planned to have only 100 applications available by the end of 1981, stating that "This tiny figure has to put a chill on the whole industry". Green's company,
Instant Software Instant Software was a company that produced game, utility, and education software in the late 1970s and early 1980s primarily for the TRS-80 line of home computers. Instant Software was a subsidiary of Kilobaud Microcomputing, headquartered in Pete ...
, was a prolific publisher for the
TRS-80 The TRS-80 Micro Computer System (TRS-80, later renamed the Model I to distinguish it from successors) is a desktop microcomputer developed by American company Tandy Corporation and sold through their Radio Shack stores. Launched in 1977, it is ...
but could not find anyone to port software to the TI. He wrote, "We understand the problems with the system and the efforts Texas Instruments made to make translation difficult". A
Spinnaker Software Spinnaker Software Corporation was an American software and video game company. Founded in 1982 by Bill Bowman and C. David Seuss, it was known primarily for its line of non-curriculum based educational software, which was a major seller during ...
executive said that the 99/4A had "the worst software in the business", and Ahl noted that unlike other computers, it did not have "
Microsoft BASIC Microsoft BASIC is the foundation software product of the Microsoft company and evolved into a line of BASIC interpreters and compiler(s) adapted for many different microcomputers. It first appeared in 1975 as Altair BASIC, which was the first v ...
,
VisiCalc VisiCalc ("visible calculator") is the first spreadsheet computer program for personal computers, originally released for the Apple II by VisiCorp on October 17, 1979. It is considered the killer application for the Apple II, turning the microco ...
,
WordStar WordStar is a discontinued word processor application for microcomputers. It was published by MicroPro International and originally written for the CP/M-80 operating system (OS), with later editions added for MS-DOS and other 16-bit computing, ...
, or any popular games". Peripherals cost about twice as much as for other computers. TI joysticks were of poor quality and difficult to find, for example; one reseller reported that its best-selling product was the
Atari CX40 joystick The Atari CX40 joystick was the first widely used cross-platform game controller. The original CX10 was released with the Atari Video Computer System (later renamed the Atari 2600) in 1977 and became the primary input device for most games on the ...
adapter cable. Pournelle added, "TI had rightly concluded that the hobbyists and hackers were a tiny part of the market and ''wrongly'' concluded that they were therefore unimportant". Rivals were more open with information. ''Kilobaud Microcomputing'' reported that a Commodore executive promised the VIC-20 would have "enough additional documentation to enable an experienced programmer/hobbyist to get inside and let his imagination work". Even when competitors did not disclose technical information, because their computers used
commercial off-the-shelf Commercial-off-the-shelf or commercially available off-the-shelf (COTS) products are packaged or canned (ready-made) hardware or software, which are adapted aftermarket to the needs of the purchasing organization, rather than the commissioning of ...
parts like
MOS 6502 The MOS Technology 6502 (typically pronounced "sixty-five-oh-two" or "six-five-oh-two") William Mensch and the moderator both pronounce the 6502 microprocessor as ''"sixty-five-oh-two"''. is an 8-bit microprocessor that was designed by a small ...
and
Zilog Z80 The Zilog Z80 is an 8-bit computing, 8-bit microprocessor designed by Zilog that played an important role in the evolution of early personal computing. Launched in 1976, it was designed to be Backward compatibility, software-compatible with the ...
, much more information was public than for TI's proprietary components. IBM learned from TI's mistake, Pournelle said. The company released software and hardware technical information when the
IBM PC The IBM Personal Computer (model 5150, commonly known as the IBM PC) is the first microcomputer released in the List of IBM Personal Computer models, IBM PC model line and the basis for the IBM PC compatible ''de facto'' standard. Released on ...
was announced in 1981, stating that "the definition of a personal computer ''is'' third-party hardware and software". TI had also learned from its mistake and no longer ignored hobbyists, Pournelle said in 1982. The company advertised in ''BYTE'' its program for publishing others' software, and job openings for software developers. By mid-1983 more than 1000 applications were available. TI insisted on being the sole publisher for the system, however, which many developers refused to agree to. After
third-party developer A video game developer is a software developer specializing in video game development – the process and related disciplines of creating video games. A game developer can range from one person who undertakes all tasks to a large business with em ...
s' games for the Atari 2600 became very successful, the company at the June 1983
Consumer Electronics Show CES (; formerly an initialism for Consumer Electronics Show) is an annual trade show organized by the Consumer Technology Association (CTA). Held in January at the Las Vegas Convention Center in Winchester, Nevada, United States, the event typi ...
announced that only cartridges with a TI-licensed
lockout chip In a general sense, a lockout chip is a chip within an electronic device to prevent other manufacturers from using a company's device to perform certain functions. A notable example is the lockout chip found in Nintendo's Nintendo Entertainment S ...
would work in the 99/4A. TI held a patent on a
program counter The program counter (PC), commonly called the instruction pointer (IP) in Intel x86 and Itanium microprocessors, and sometimes called the instruction address register (IAR), the instruction counter, or just part of the instruction sequencer, ...
implemented in software in GROM, which a future operating system revision would require in cartridges. The ''
Boston Phoenix ''The Phoenix'' (stylized as ''The Phœnix'') was the name of several alternative weekly periodicals published in the United States by Phoenix Media/Communications Group of Boston, Massachusetts, including the now defunct ''Boston Phoenix'', '' ...
'' predicted that "most oftware developersjust won't bother making TI-compatible versions of their programs", and Pournelle wrote that "TI once again tells the hobbyists to drop dead". No official technical documentation from TI was released until the "Editor/Assembler" development suite was announced in 1981 and released in 1982, and no system schematics were ever released to the public until after TI had discontinued the computer.


Discontinuation

After TI in mid-1983 unexpectedly announced a loss in the second calendar quarter—implying a pretax loss from home computers of —its stock dropped by one third in two days. The ''Times'' stated in June 1983 that Cosby's refund "joke is no longer funny", and that "future options are slim". The low price affected the 99/4A's reputation; "When they went to , people started asking 'What's wrong with it?'", one retail executive said. An L.F. Rothschild
sell-side analyst A sell-side analyst works for an investment bank or a brokerage firm and evaluates companies for future earnings growth and other investment criteria. Aside from stimulating buying and selling, the reliability of the research will help the client m ...
estimated that TI had prepared to manufacture three million computers in 1983, but would only be able to sell two million; another analyst forecast one million for the year. Some observers predicted after the second quarter's loss that the 99/4A would not be able to recover; even if the company did not plan to discontinue the computer, the fear that it would become
orphaned technology Orphaned technology refers to computer technologies that have been abandoned by their original developers. As opposed to deprecation, which tends to be a gradual shift away from an older technology to newer technology, orphaned technology is usua ...
might cause retailers to avoid ordering inventory. Others thought that TI could sell excess inventory and continue producing the computer. After losing after taxes in the third calendar quarter of 1983, TI announced plans to discontinue the 99/4A, while continuing to sell the TI Professional
MS-DOS MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few op ...
-compatible computer. (TI stock rose by 25% after the announcement, because the company's other businesses were strong.) With another TI price cut, retailers sold remaining inventory of the former computer during Christmas for $49. The 90
Child World Child World was an American toy retailer founded in 1962. It grew to 182 sites and revenues of $830 million (~$ in ) before failing in 1992. It was known for the distinctive stylized castle store exterior adopted after its 1975 purchase of the C ...
stores quickly sold over 40,000 computers at a price referred to as "nearly a stocking stuffer" in a ''Times'' article. A total of 2.8 million units were shipped before the TI-99/4A was discontinued in March 1984, perhaps the largest installed base among all personal computers. The 99/4A became the first in a series of home computers to be orphaned by their manufacturer over the next few years, along with the
Coleco Adam The Coleco Adam is a home computer and expansion device for the ColecoVision by American toy and video game manufacturer Coleco. The Adam was an attempt to follow on the success of the company's ColecoVision video game console. It was available as ...
,
Mattel Aquarius The Aquarius is a home computer designed by ''Radofin'' and released by ''Mattel Electronics'' in 1983. Based on the Zilog Z80 microprocessor, the system has a rubber chiclet keyboard, 4 kB of RAM, and a subset of Microsoft BASIC in ROM. It conn ...
,
Timex Sinclair 1000 The Timex Sinclair 1000 (or T/S 1000) was the first computer produced by Timex Sinclair, a joint venture between Timex Corporation and Sinclair Research. It was launched in July 1982, with a US sales price of US$99.95, making it the cheapest hom ...
, and
IBM PCjr The IBM PCjr (pronounced "PC junior") was a home computer produced and marketed by IBM from March 1984 to May 1985, intended as a lower-cost variant of the IBM PC with hardware capabilities better suited for video games, in order to compete mor ...
.


Architecture

In order to build a complete 16-bit system, TI would have had to redesign many of their existing 8-bit support chips. Instead, TI decided to use existing devices for the majority of the system. The result is that only a small portion of the system is 16-bit and uses a second 8-bit
computer bus In computer architecture, a bus (historically also called a data highway or databus) is a communication system that transfers data between components inside a computer or between computers. It encompasses both hardware (e.g., wires, optical ...
for the rest. One of the key features of the TMS9900 from the minicomputer design that spawned it is the inclusion of several sets of
processor register A processor register is a quickly accessible location available to a computer's processor. Registers usually consist of a small amount of fast storage, although some registers have specific hardware functions, and may be read-only or write-onl ...
s. In a minicomputer setting, the system was typically running a
time-sharing In computing, time-sharing is the Concurrency (computer science), concurrent sharing of a computing resource among many tasks or users by giving each Process (computing), task or User (computing), user a small slice of CPU time, processing time. ...
or multitasking
operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...
, or being used for
real-time computing Real-time computing (RTC) is the computer science term for Computer hardware, hardware and software systems subject to a "real-time constraint", for example from Event (synchronization primitive), event to Event (computing), system response. Rea ...
, both of which benefit from being able to quickly switch among programs. To do this, the TMS9900 stores several sets of registers in main memory and can switch between the sets of sixteen 16-bit registers by changing the single workspace pointer register, thereby allowing very rapid
context switch In computing, a context switch is the process of storing the state of a process or thread, so that it can be restored and resume execution at a later point, and then restoring a different, previously saved, state. This allows multiple processes ...
ing. The new design put 256 bytes of
random-access memory Random-access memory (RAM; ) is a form of Computer memory, electronic computer memory that can be read and changed in any order, typically used to store working Data (computing), data and machine code. A random-access memory device allows ...
(RAM) on the 16-bit bus to store up to eight sets of registers. This area of RAM is known as the "
scratchpad memory Scratchpad memory (SPM), also known as scratchpad, scratchpad RAM or local store in computer terminology, is an internal memory, usually high-speed, used for temporary storage of calculations, data, and other work in progress. In reference to a m ...
". As the processor's instructions are all 16-bit as well, the 8 KB internal system
read-only memory Read-only memory (ROM) is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM cannot be electronically modified after the manufacture of the memory device. Read-only memory is useful for storing sof ...
(ROM) was also on the 16-bit side. Only the
program counter The program counter (PC), commonly called the instruction pointer (IP) in Intel x86 and Itanium microprocessors, and sometimes called the instruction address register (IAR), the instruction counter, or just part of the instruction sequencer, ...
, status register, and workspace pointer registers are actually implemented on the chip itself. Included on the 8-bit side of the system is the majority of the RAM and almost all of the support chips, especially the
video display controller A video display controller (VDC), also called a display engine or display interface, is an integrated circuit which is the main component in a video-signal generator, a device responsible for the production of a TV video signal in a computing ...
(VDP). All accesses to the VDP system are executed eight bits at a time. The system's RAM is managed by the VDP, which provides access to the CPU only when the VDP is not using the memory. This means that user programs and data are read over two machine cycles, reducing speed by half. According to TI's former manager for microprocessors who oversaw TMS9900 development, this negates the performance advantage of a 16-bit processor. The TMS9900's
machine language In computer programming, machine code is computer code consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). For conventional binary computers, machine code is the binaryOn nonb ...
instructions must be word-aligned, so at least 16-bits are needed for every instruction. At the time, memory was expensive, so the size of this format was a concern. Additionally, programming the 8-bit side of the system from 16-bit code is somewhat complex. To address this, TI developed a pseudo-
assembly language In computing, assembly language (alternatively assembler language or symbolic machine code), often referred to simply as assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence bet ...
known as "Graphic Programming Language", or GPL. This is a compact 8-bit language interpreted by the CPU which dynamically translates the GPL instructions into one or more TMS9900 instructions. GPL includes utility routines that appear as single instructions in GPL code, such as clearing a block of memory. All software originally distributed on
ROM cartridge A ROM cartridge, usually referred to in context simply as a cartridge, cart, cassette, or card, is a replaceable part designed to be connected to a consumer electronics device such as a home computer, video game console or, to a lesser extent, ...
s were written using GPL, and are sometimes referred to as GROMs. At the time of launch, the system included only a single user-accessible
programming language A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually def ...
: TI's built-in BASIC interpreter, written in GPL. On the
Creative Computing Benchmark The Creative Computing Benchmark, also called Ahl's Simple Benchmark, is a Benchmark (computing), computer benchmark that was used to compare the performance of the BASIC programming language on various machines. It was first introduced in the Nove ...
, it runs at roughly half the speed of the
Apple II Apple II ("apple Roman numerals, two", stylized as Apple ][) is a series of microcomputers manufactured by Apple Computer, Inc. from 1977 to 1993. The Apple II (original), original Apple II model, which gave the series its name, was designed ...
. Computers manufactured from August 1983 and later may have the lockout chip preventing use of unlicensed cartridges. Such "QI" units have a 1983 copyright date at bootup.


Technical specifications


CPU

TMS9900 The TMS9900 was one of the first commercially available single-chip 16-bit microprocessors. Introduced in June 1976, it implemented Texas Instruments's TI-990 minicomputer architecture in a single-chip format, and was initially used for low-end ...
@ 3 megahertz, MHz,
16-bit 16-bit microcomputers are microcomputers that use 16-bit microprocessors. A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two ...
, 64-pin DIP


Memory

* 8 KB of monitor ROM and GPL interpreter * 8 KB of RAM, if memory expansion is attached * 8 KB allocated to expansion devices (e.g. disk drive controller) * 8 KB allocated to ROM/RAM in expansion cartridges *256 bytes scratchpad RAM for the CPU * Memory ports for Video Display Processor, sound, speech etc. * 24 KB RAM, if memory expansion is attached *16 KB Video Display Processor RAM accessible via the VDP (not in CPU's memory map) * 18KB GPL GROM (6KB GPL OS support, 12KB TI Basic GPL GROM Language)


Video

TMS9918A VDP TMS9918A VDP TMS9918A The TMS9918 is a video display controller (VDC) manufactured by Texas Instruments, in manuals referenced as "Video Display Processor" (VDP) and introduced in 1979. The TMS9918 and its variants were used in the Casio PV ...
video display processor, 40 pin DIP. The earlier 99/4 uses the TMS9918. PAL systems use the "9929" versions of each. * 32 single-color sprites in defined layers allowing higher-numbered sprites to transparently flow over lower-numbered sprites. Sprites are available at 8×8 pixels or 16×16 pixels, with a "magnify" bit that doubled all sprites' size but not their resolution. A single bit is available in hardware for
collision detection Collision detection is the computational problem of detecting an intersection of two or more objects in virtual space. More precisely, it deals with the questions of ''if'', ''when'' and ''where'' two or more objects intersect. Collision detect ...
, and the console supports automatic movement via an interrupt routine in the ROM. There can only be 4 visible sprites per
scan line A scan line (also scanline) is one line, or row, in a raster scanning pattern, such as a line of video on a cathode-ray tube (CRT) display of a television set or computer monitor. On CRT screens the horizontal scan lines are visually discernib ...
. * 16 fixed colors (15 visible, one color reserved for "transparent" which shows the background color). Transparent is intended for the 9918's
genlock Genlock (generator locking) is a common technique where the video output of one source (or a specific reference signal from a signal generator) is used to synchronize other picture sources together. The aim in video applications is to ensure the ...
which is disabled in the system. * Text mode: 40×24 characters (256 6×8 user-definable characters, no sprites, foreground and background color only, not accessible in BASIC, standard in the p-system/Pascal, assembly editor and word processor) * Graphics mode: 32×24 characters (256 8×8 user-definable characters), full 15 color palette + transparent (available in groups of 8 through the character table) and 32 sprites (The only mode available in BASIC. Extended BASIC is required for sprites, and can access only 28 of them.) * Bitmap mode: 256×192 pixels (no more than two colors in an eight-pixel row, full 15 color palette + transparent, all 32 sprites available but interrupt-based motion through the ROM routine is not due to the memory layout, not available to BASIC or the original 9918). * Multicolor mode: 64×48 pixels (each pixel may be any color, all 32 sprites are available) * All of the above comprise 36 layers starting with the video overlay input, then the background color, then two graphics mode layers, then a layer for each of the 32 sprites. A higher layer obscures a lower layer in hardware, unless that higher layer is transparent.


Sound

TMS9919, later SN94624, identical to the
SN76489 The Texas Instruments SN76489 is a programmable sound generator chip from the 1980s, used to create music and sound effects on computers and video game systems. Initially developed by Texas Instruments for its TI-99/4A home computer, it was later ...
used in many other systems * 3 voices, 1 noise (white or periodic) * Voices generate square waves from 110 Hz to approximately 115 kHz * Console ROM includes interrupt-driven music playback


Games

Roughly 100 games were published for the TI-99/4A, with most published by Texas Instruments. Some of the games released only for the 99/4A are ''Parsec'', ''Alpiner'', '' Tombstone City: 21st Century'', '' Tunnels of Doom'', and '' The Attack''. ''
TI Invaders ''TI Invaders'' is a fixed shooter video game published by Texas Instruments in 1981 for the TI-99/4A home computer. The game is a ''Space Invaders'' clone where the goal is to shoot all of the aliens before they reach the bottom of the screen. ...
'' and ''Car Wars'' are TI's renditions of ''
Space Invaders is a 1978 shoot 'em up video game developed and published by Taito for Arcade video game, arcades. It was released in Japan in April 1978, with the game being released by Midway Manufacturing overseas. ''Space Invaders'' was the first fixed s ...
'' and '' Head On'' respectively. '' Munch Man'' is similar to ''
Pac-Man ''Pac-Man,'' originally called in Japan, is a 1980 maze video game developed and published by Namco for arcades. In North America, the game was released by Midway Manufacturing as part of its licensing agreement with Namco America. The pla ...
'', but the title character fills the maze with a pattern rather than emptying it of dots. The
Adventure International Adventure International was an American video game publisher, video game publishing company that existed from 1979 until 1986. It was started by Scott Adams (game designer), Scott and Alexis Adams. Their games were notable for being the first i ...
text adventure Interactive fiction (IF) is software simulating environments in which players use text Command (computing), commands to control Player character, characters and influence the environment. Works in this form can be understood as literary narrati ...
s require the Adventure Command Module cartridge.
Tigervision Tigervision was a subsidiary of Tiger Toys which produced video games for the Atari 2600, Atari 8-bit computers, TI-99/4A, VIC-20, and Commodore 64. Most of their games were ports. ''Polaris'' and '' River Patrol'' were originally arcade games fro ...
offered a solution to the memory limitation of the standard cartridge slot in the form of a 24 KB memory expansion cartridge that attached to the side expansion interface, emulating an expansion device. This allowed the company to implement a larger game completely in machine code, which was used for ''Espial'' and ''
Miner 2049er ''Miner 2049er'' is a 1982 platformer game developed and published by Big Five Software in December 1982. It is set in a mine, where the player controls the Mountie Bounty Bob. The player controls Bounty Bob through multiple levels of a mine, ...
''. Exceltec also released two similar side cartridges: ''Arcturus'' and ''Killer Caterpillar''. The media criticized the computer's game library as mediocre. TI not only discouraged third-party development, including games, but it also failed to license popular arcade games like ''
Zaxxon is a scrolling shooter game developed and released by Sega as an arcade video game. It had a limited release in December 1981, followed by a wide release in January 1982. In the game, the player pilots a ship through heavily defended space fortr ...
'' and ''
Frogger is a 1981 arcade action game developed by Konami and published by Sega. In North America, it was distributed by Sega/Gremlin. The object of the game is to direct five frogs to their homes by dodging traffic on a busy road, then crossing a ri ...
''.


Unreleased hardware


Hex-Bus

The
Hex-Bus The Texas Instruments Hex-Bus interface (sometimes used unhyphenated as Hex Bus and with varying capitalization) was designed in 1982 and intended for commercial release in late 1983. It connects the console to peripherals via a high-speed seri ...
interface was designed in 1982 and intended for commercial release in late 1983. It connects the console to peripherals via a high-speed serial link. Though it is similar to today's
USB Universal Serial Bus (USB) is an industry standard, developed by USB Implementers Forum (USB-IF), for digital data transmission and power delivery between many types of electronics. It specifies the architecture, in particular the physical ...
(
plug and play In computing, a plug and play (PnP) device or computer bus is one with a specification that facilitates the recognition of a hardware component in a system without the need for physical device configuration or user intervention in resolving reso ...
,
hot-swappable Hot swapping is the replacement or addition of components to a computer system without stopping, shutting down, or rebooting the system. Hot plugging describes only the addition of components to a running computer system. Components which ha ...
, etc.), it was never released, with only a small number of prototypes appearing in collector hands after TI pulled out of the market.


TI-99/4A successors

The TI-99/4 was intended to fit in the middle of a planned range of TI-99 computers, with prototypes and documentation created for other models. Initial plans were for a lower-end TI-99/2 and a more powerful TI-99/8. Later ideas for expanding the range included a bargain-priced TI-99/3, a terminal TI-99/7, and a direct follow-up to the TI-99/4A referred to as either TI-99/4B or TI-99/5. At the time they left the home computer market, TI had been actively developing two successors to the TI-99/4A that went through several prototypes but never entered production. Some of these prototypes are now in the hands of TI-99/4A collectors. Both machines would have been substantially faster than the original TI-99/4A and used the
Hex-Bus The Texas Instruments Hex-Bus interface (sometimes used unhyphenated as Hex Bus and with varying capitalization) was designed in 1982 and intended for commercial release in late 1983. It connects the console to peripherals via a high-speed seri ...
serial interface. * TI-99/2, a 4K RAM, 32K ROM computer with no color, sound, or joystick port and a
Mylar BoPET (biaxially oriented polyethylene terephthalate) is a polyester film made from stretched polyethylene terephthalate (PET) and is used for its high tensile strength, chemical stability, dimensional stability, transparency reflectivity, an ...
keyboard. TI designed the computer in four and a half months to sell for under $100 and compete with the
Sinclair ZX81 The ZX81 is a home computer that was produced by Sinclair Research and manufactured in Dundee, Scotland, by Timex Corporation. It was launched in the United Kingdom in March 1981 as the successor to Sinclair's ZX80 and designed to be a low- ...
and
Timex Sinclair 1000 The Timex Sinclair 1000 (or T/S 1000) was the first computer produced by Timex Sinclair, a joint venture between Timex Corporation and Sinclair Research. It was launched in July 1982, with a US sales price of US$99.95, making it the cheapest hom ...
. Based on the TMS9995 CPU running at 10.7 MHz and with a built-in RF modulator, performance greatly increased when the screen was blank. The
University of Southwestern Louisiana The University of Louisiana at Lafayette (UL Lafayette, University of Louisiana, ULL, or UL) is a public research university in Lafayette, Louisiana, United States. It has the largest enrollment within the nine-campus University of Louisiana Sys ...
developed system software. 99/2 software ran on the 99/4A, but not vice versa. Working prototypes appeared at the January 1983 Consumer Electronic Show (CES). By mid-1983 the 99/4A sold for $99, however. The company canceled the 99/2 in April 1983, but planned to exhibit it at the June CES until other companies' press conferences there indicated that competition would increase. * TI-99/8 and 99/6. The 99/8 reportedly had a $200 wholesale price. Privately shown to dealers but not announced at June CES, it was formally canceled in October 1983. It included 64 KB of RAM expandable to 15
megabyte The megabyte is a multiple of the unit byte for digital information. Its recommended unit symbol is MB. The unit prefix ''mega'' is a multiplier of (106) in the International System of Units (SI). Therefore, one megabyte is one million bytes ...
s, a larger keyboard, built-in speech synthesis, built-in
UCSD Pascal UCSD Pascal is a Pascal programming language system that runs on the UCSD p-System, a portable, highly machine-independent operating system. UCSD Pascal was first released in 1977. It was developed at the University of California, San Diego (UC ...
operating environment, and the full 16-bit data bus available on the expansion port. It was abandoned in the prototype stage. The
Multi Emulator Super System Multi Emulator Super System (MESS) was an emulator for various consoles and computer systems, based on the MAME core. It used to be a standalone program (which has since been discontinued), but is now integrated into MAME (which is actively dev ...
is capable of running what are believed to be the system's ROMs.


Legacy

The
Tomy Tutor The Tomy Tutor, originally sold in Japan as the and in the UK as the Grandstand Tutor, is a home computer produced by the Japanese toymaker Tomy. It is architecturally similar, but not identical, to the TI-99/4A, and uses a similar Texas Instrum ...
and its sibling systems are Japanese computers similar in architecture and firmware to the 99/8. Unlike the 99/8, it was released commercially, but sold poorly outside Japan. Portions of the operating system and BASIC code are similar to the 99/8. The annual Chicago TI Faire is now in its 42nd year. where people celebrated the TI-99 family of computers.


Post-TI development

The Myarc Geneve 9640 is an enhanced TI-99/4A clone built by Myarc as a card to fit into the TI Peripheral Expansion System. It uses an
IBM PC/XT The IBM Personal Computer XT (model 5160, often shortened to PC/XT) is the second computer in the IBM Personal Computer line, released on March 8, 1983. Except for the addition of a built-in hard drive and extra expansion slots, it is very simi ...
detached keyboard. Released in 1987, it is similar to the unreleased TI-99/8 system. It includes a 12 MHz TMS9995 processor, enhanced graphics with 80-column text mode, 16-bit wide RAM, MDOS, and is compatible with nearly all TI software and slot-mounted hardware. A toggle switch slows the computer to the speed of the original. The Second Generation CPU card (SGCPU) was released by the System 99 User Group in 1996 as a card to be installed in the PEB. In 2004, a
Universal Serial Bus Universal Serial Bus (USB) is an industry standard, developed by USB Implementers Forum (USB-IF), for digital data transmission and power delivery between many types of electronics. It specifies the architecture, in particular the physical ...
card and
Advanced Technology Attachment Parallel ATA (PATA), originally , also known as Integrated Drive Electronics (IDE), is a standard interface designed for IBM PC-compatible computers. It was first developed by Western Digital and Compaq in 1986 for compatible hard drives and C ...
controller for IDE
hard disk A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating hard disk drive platter, pla ...
s for the PEB were released. A range of plug-in cartridge boards have been developed, allowing software projects to be distributed on cartridge. The Phoenix G2, was designed in 2010 by Gary Smith, a member of TI-User Group UK. It uses two FPGAs to emulate the entire architecture of the Myarc Geneve 9640 and the TMS9995 microprocessor. It incorporates an
SD card Secure Digital (SD) is a proprietary, non-volatile, flash memory card format developed by the SD Association (SDA). Owing to their compact size, SD cards have been widely adopted in a variety of portable consumer electronics, including dig ...
reader, Ethernet,
VGA Video Graphics Array (VGA) is a video display controller and accompanying de facto graphics standard, first introduced with the IBM PS/2 line of computers in 1987, which became ubiquitous in the IBM PC compatible industry within three years. T ...
output, and 64 MB RAM. An FPGA-based TMS9918 compatible graphics chip, called the F18A, is a drop-in replacement for the original 9918 VDP, but features VGA output, bypassing the TMS9918A's native composite output, and contains other enhancements such as removal of the restriction of 4 sprites per scan line.


See also

*
Compact Computer 40 The Compact Computer 40, or CC-40, is a notebook-sized computer developed by Texas Instruments. It started development in 1981, and was released in March 1983 for US$249. The CC-40 has a single-line 31 character LCD display, weighs and is powe ...
(1983) *
Texas Instruments Professional Computer The Texas Instruments Professional Computer (abbreviated TIPC or TI PC) and the Texas Instruments Professional Portable Computer (TIPPC) are personal computers produced by Texas Instruments (TI) that were both released on January 31, 1983, and di ...
(1983 – ) *
Texas Instruments Professional Portable Computer The Texas Instruments Portable Professional Computer (TIPPC) is a portable version of the Texas Instruments Professional Computer (TIPC), both of which were released on January 31, 1983. The TIPC is a desktop PC and the TIPPC is a fully compatible, ...
(1983)


References


External links


Ninerpedia
wiki devoted to the TI-99 series
1979 TI-99/4The TI-99/4A Home Computer PageTI-99/4A - PEDIA
{{DEFAULTSORT:Texas Instruments Ti-99 4a Home computers 16-bit computers Computer-related introductions in 1979