The KIM-1, short for ''Keyboard Input Monitor'', is a small

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 ...

-based

single-board computer A single-board computer (SBC) is a complete computer built on a single circuit board, with microprocessor(s), memory, input/output (I/O) and other features required of a functional computer. Single-board computers are commonly made as demonst ...

developed and produced by MOS Technology, Inc. and launched in 1976. It was very successful in that period, due to its low price (thanks to the inexpensive 6502 microprocessor) and easy-access expandability.

History

MOS Technology's first processor, the 6501, could be plugged into existing motherboards that used the Motorola 6800, allowing potential users (i.e. engineers and hobbyists) to get a development system up and running very easily using existing hardware.

Motorola Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois. It was founded by brothers Paul and Joseph Galvin in 1928 and had been named Motorola since 1947. Many of Motorola's products had been ...

immediately sued, forcing MOS to pull the 6501 from the market. Changing the pin layout produced the "lawsuit-friendly"

. Otherwise identical to the 6501, it nevertheless had the disadvantage of having no machine in which new users could quickly start using the CPU. Chuck Peddle, leader of the 650x group at MOS (and former member of Motorola's 6800 team), designed the KIM-1 in order to fill this need. The KIM-1 came to market in 1976. While the machine was originally intended to be used by engineers, it quickly found a large audience with hobbyists. A complete system could be constructed for under with the purchase of the computer itself for only , and then adding a power supply, a secondhand terminal and a cassette tape drive. Many books were available demonstrating small

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 ...

programs for the KIM, including ''The First Book of KIM'' by Jim Butterfield ''et al''. One demo program converted the KIM into a music box by toggling a software-controllable output bit connected to a small

loudspeaker A loudspeaker (commonly referred to as a speaker or, more fully, a speaker system) is a combination of one or more speaker drivers, an enclosure, and electrical connections (possibly including a crossover network). The speaker driver is an ...

. Canadian programmer Peter R. Jennings produced what was probably the first game for microcomputers to be sold commercially, '' Microchess,'' originally for the KIM-1. As the system became more popular, one of the common additions was the Tiny BASIC programming language. This required an easy memory expansion; "all of the decoding for the first 4 K is provided right on the KIM board. All you need to provide is 4 K more of RAM chips and some buffers." The hard part was loading the BASIC from

cassette tape The Compact Cassette, also commonly called a cassette tape, audio cassette, or simply tape or cassette, is an analog audio, analog magnetic tape recording format for Sound recording and reproduction, audio recording and playback. Invented by L ...

—a 15-minute, error-prone ordeal.

Rockwell International Rockwell International was a major American manufacturing conglomerate (company), conglomerate. It was involved in aircraft, the space industry, defense and commercial electronics, components in the automotive industry, printing presses, avioni ...

—who second-sourced the 6502, along with

Synertek Synertek, Inc. was an American semiconductor manufacturer founded in 1973. The initial staff consisted of Bob Schreiner (the CEO), Dan Floyd, Jack Balletto, and Gunnar Wetlesen and Zvi Grinfas. Schreiner, Floyd, Balletto and Wetlesen were all forme ...

—released their own microcomputer in one board in 1978, the AIM-65. The AIM included a full

ASCII ASCII ( ), an acronym for American Standard Code for Information Interchange, is a character encoding standard for representing a particular set of 95 (English language focused) printable character, printable and 33 control character, control c ...

keyboard, a 20-character 14-segment

alphanumeric Alphanumericals or alphanumeric characters are any collection of number characters and letters in a certain language. Sometimes such characters may be mistaken one for the other. Merriam-Webster suggests that the term "alphanumeric" may often ...

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 ...

display, and a small

cash register A cash register, sometimes called a till or automated money handling system, is a mechanical or electronic device for registering and calculating transactions at a point of sale. It is usually attached to a Cash register#Cash drawer, drawer fo ...

-like printer. A

debug In engineering, debugging is the process of finding the root cause, workarounds, and possible fixes for bugs. For software, debugging tactics can involve interactive debugging, control flow analysis, log file analysis, monitoring at the ap ...

monitor Monitor or monitor may refer to: Places * Monitor, Alberta * Monitor, Indiana, town in the United States * Monitor, Kentucky * Monitor, Oregon, unincorporated community in the United States * Monitor, Washington * Monitor, Logan County, Wes ...

was provided as standard

firmware In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, h ...

for the AIM, and users could also purchase optional

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 * ...

chips with an assembler and a

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 ...

interpreter Interpreting is translation from a spoken or signed language into another language, usually in real time to facilitate live communication. It is distinguished from the translation of a written text, which can be more deliberative and make use o ...

to choose from. Finally, there was the Synertek

SYM-1 The SYM-1 is a single board "trainer" computer produced by Synertek Systems in 1975. It was designed by Ray Holt. Originally called the VIM-1 (Versatile Input Monitor), that name was later changed to SYM-1. The SYM-1 is a close copy of the po ...

variant, which could be said to be a machine halfway between the KIM and the AIM; it had the KIM's small display, and a simple

membrane keyboard A membrane keyboard is a computer keyboard whose keys are not separate, moving parts, as with the majority of other keyboards, but rather are pressure pads that have only outlines and symbols printed on a flat, flexible surface. Very little tacti ...

of 29 keys (hex digits and control keys only), but provided AIM-standard expansion interfaces and true

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 ...

(voltage level as well as current loop mode supported).

Description

The KIM-1 consisted of a single

printed circuit board A printed circuit board (PCB), also called printed wiring board (PWB), is a Lamination, laminated sandwich structure of electrical conduction, conductive and Insulator (electricity), insulating layers, each with a pattern of traces, planes ...

with all the components on one side. It included three main ICs; the MCS6502 CPU and two MCS6530 Peripheral Interface/Memory Devices. Each MCS6530 comprises a mask programmable 1024 × 8 ROM, a 64 × 8 RAM, two eight-bit bi-directional ports, and a programmable interval timer. The KIM-1 brochure said "1 K BYTE RAM" but it actually had 1152 bytes. The memory was composed of eight 6102 static RAMs (1024 × 1 bits) and the two 64-byte RAMs of the MCS6530s. In the 1970s memory sizes were expressed in several ways. Semiconductor manufacturers would use a precise memory size such as 2048 by 8 and sometimes state the number of bits (16384). Mini and mainframe computers had various memory widths (8 bits to over 36 bits) so manufacturers would use the term "words", such as 4K words. The early hobbyist computer advertisements would use both "words" and "bytes". It was common to see "4096 words", "4K (4096) words" and "4 K bytes". The term KB was unused or very uncommon. The KIM-1 was introduced in the April 1976 issue of ''

BYTE The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable un ...

'' and the advertisement stated "1 K BYTE RAM" and "2048 ROM BYTES". Also included were six 7-segment LEDs (similar to those on a pocket

calculator An electronic calculator is typically a portable electronic device used to perform calculations, ranging from basic arithmetic to complex mathematics. The first solid-state electronic calculator was created in the early 1960s. Pocket-si ...

) and a 24-key calculator-type keypad. Many of the pins of the I/O portions of the 6530s were connected to two connectors on the edge of the board, where they could be used as a serial system for driving a

Teletype Model 33 The Teletype Model 33 is an electromechanical teleprinter designed for light-duty office use. It is less rugged and cost less than earlier Teletype models. The Teletype Corporation introduced the Model 33 as a commercial product in 1963, after ...

ASR and paper tape reader and punch. One of these connectors also doubled as the power supply connector and included analog lines that could be attached to a

recorder. Earlier

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 ...

systems such as the MITS Altair used a series of switches on the front of the machine to enter data. In order to do anything useful, the user had to enter a small program known as the "bootstrap loader" into the machine using these switches, a process known as

booting In computing, booting is the process of starting a computer as initiated via Computer hardware, hardware such as a physical button on the computer or by a software command. After it is switched on, a computer's central processing unit (CPU) h ...

. Once loaded, the loader would be used to load a larger program off a storage device like a

paper tape Five- and eight-hole wide punched paper tape Paper tape reader on the Harwell computer with a small piece of five-hole tape connected in a circle – creating a physical program loop Punched tape or perforated paper tape is a form of data st ...

reader. It would often take upwards of five minutes to load the tiny program into memory, and a single error while flipping the switches meant that the bootstrap loader would crash the machine. This could render some of the bootstrap code garbled, in which case the programmer had to reenter the whole thing and start all over again. The KIM-1 included a somewhat more complex built-in Terminal Interface Monitor software called TIM that was "contained in 2048 bytes of ROM in two 6530 ROM/RAM/IO arrays". This monitor software included the ability to run a cassette tape for storage, drive the LED display, and run the keypad. As soon as the power was turned on, the monitor would run and the user could immediately start interacting with the machine via the keypad. The KIM-1 was one of the first

s, needing only an external power supply to enable its use as a stand-alone experimental computer. This fact, plus the relatively low cost of getting started, made it quite popular with hobbyists through the late 1970s.

Video display

The designer of the

TV Typewriter The TV Typewriter is a video terminal that could display two pages of 16 lines of 32 upper case characters on a standard television set. The design, by Don Lancaster, appeared on the cover of ''Radio-Electronics'' magazine in September 1973. The ...

, Don Lancaster, developed a low-cost video display for the KIM-1. The add-on board would display up to 4000 characters on a TV or monitor. A typical configuration would be 16 lines of 32 upper-case only characters. The board had only 10 low-cost ICs and used the KIM's memory for the screen storage. The TVT-6 project appeared on the cover on ''

Popular Electronics ''Popular Electronics'' was an American magazine published by John August Media, LLC, and hosted at TechnicaCuriosa.com. The magazine was started by Ziff-Davis Publishing Company in October 1954 for electronics hobbyists and experimenters. It so ...

'' in July 1977. The complete kit could be ordered from PAiA Electronics for . Lancaster expanded this design to do color and simple graphics in ''The Cheap Video Cookbook''.

Specifications

* CPU: MCS6502 - clocked at 1 MHz * two PIO MCS6530 - , , two 8-bit bi-directional ports, 8-bit programmable interval timer * eight 6102

static RAM Static random-access memory (static RAM or SRAM) is a type of random-access memory (RAM) that uses latching circuitry (flip-flop) to store each bit. SRAM is volatile memory; data is lost when power is removed. The ''static'' qualifier differ ...

- 1024 × 1 (1024 bytes) * six 7-segment LEDs * 24-key calculator type

keypad A keypad is a block or pad of buttons set with an arrangement of digits, symbols, or alphabetical letters. Pads mostly containing numbers and used with computers are numeric keypads. Keypads are found on devices which require mainly numeric in ...

* two serial ports * Terminal Interface Monitor (TIM), that handled

, keypad, seven-segment LEDs, and cassette tape

Tape format

Each bit is represented by three 2.484 ms long tones. The first is always 3700 Hz, the middle is 3700 Hz for "0" or 2400 Hz for "1", and the last one is always 2400 Hz. This gives an effective bit rate of 134.2 bit/s. Detection is done through a PLL using LM565. The format of data on the tape is: 100 bytes with the value 0x16 (SYN, Synchronous Idle), one byte with the value 0x2A (*), the record identification number, the start address (two characters for the low byte of address, two characters for the high byte), the end address (in the same format), the actual data, one byte with the value 0x2F ("/" character), a two-byte

checksum A checksum is a small-sized block of data derived from another block of digital data for the purpose of detecting errors that may have been introduced during its transmission or storage. By themselves, checksums are often used to verify dat ...

, and two bytes with the value 0x04 (EOT, End Of Transmission). Each byte of memory is stored as two sequential ASCII characters on tape, for example,

hexadecimal Hexadecimal (also known as base-16 or simply hex) is a Numeral system#Positional systems in detail, positional numeral system that represents numbers using a radix (base) of sixteen. Unlike the decimal system representing numbers using ten symbo ...

B5 in memory (181 decimal) would be stored as two sequential ASCII characters "B" and "5" (42 and 35 hexadecimal).

References

External links

KIM-1
and collection of old digital and analog computers at oldcomputermuseum.com * – erik.vdbroeck's resource site for the KIM-1, with several

HTML Hypertext Markup Language (HTML) is the standard markup language for documents designed to be displayed in a web browser. It defines the content and structure of web content. It is often assisted by technologies such as Cascading Style Sheets ( ...

'ized manuals and books
Instructions on building your own KIM-1

KIM Uno
a KIM-1 emulator based on the

Arduino Arduino () is an Italian open-source hardware and open-source software, software company, project, and user community that designs and manufactures single-board microcontrollers and microcontroller kits for building digital devices. Its hardwar ...

Pro Mini {{Authority control Commodore 8-bit computers Early microcomputers Computer-related introductions in 1976