The Tandy Pocket Computer or TRS-80 Pocket Computer is a line of

pocket computer A pocket computer is a class of handheld computer characterized by very short displays (typically accommodating only one or a handful of lines of text) and calculator-style alphanumeric keypads. Pocket computers occupy a small footprint, allowin ...

s sold by

Tandy Corporation Tandy Corporation was an American family-owned Retail, retailer based in Fort Worth, Texas that made leather goods, operated the RadioShack chain, and later built personal computers. Tandy Leather was founded in 1919 as a leather supply store ...

under the Tandy 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 ...

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 ...

brands. Although named after the TRS-80 line of computers, they were not compatible with any TRS-80 desktop computer and did not use the

Z80 The Zilog Z80 is an 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 software-compatible with the Intel 8080, offering a compelling altern ...

CPU. Models in the Pocket Computer line were actually

rebadged In the automotive industry, rebadging (also known as badge engineering, an intentionally ironic misnomer in that little or no actual engineering takes place) is a form of market segmentation used by automobile manufacturers around the world. T ...

Sharp Sharp or SHARP may refer to: Acronyms * SHARP (helmet ratings) (Safety Helmet Assessment and Rating Programme), a British motorcycle helmet safety rating scheme * Self Help Addiction Recovery Program, a charitable organisation founded in 199 ...

and

Casio is a Japanese multinational electronics manufacturing corporation headquartered in Shibuya, Tokyo, Japan. Its products include calculators, mobile phones, digital cameras, electronic musical instruments, and analogue and digital watches. It ...

devices with different model names. They were given designations from PC-1 to PC-8. The PC-1, PC-2, PC-3 and PC-8 were designed by Sharp; while the PC-4, PC-5, PC-6 and PC-7 were designed by Casio.

History, lineage and nomenclature

Tandy introduced its first Pocket Computer in 1980 as an experiment; ''

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 ...

'' stated that "neither Tandy nor any of the other pocket-computer makers really know if there is a meaningful market for this machine". The magazine said that the vendors expected that businessmen would use them with a modem to communicate with larger computers. Although not branded as such, the original TRS-80 Pocket Computer later became known as the PC-1, as subsequent models were labelled PC-2 through PC-8. Some were made by Sharp, and the rest by

(PC-4 through PC-7). The PC-2 had four colored ball point pens and could print or plot on plain paper. The other print-capable models all used thermal paper, the PC-3 and PC-8 used one printer, while the PC-4, PC-5 and PC-6 used another. The PC-7 had no printer or cassette interface.

Models

The Tandy/TRS-80 model names are listed with the corresponding original Sharp or Casio model number. * ''TRS-80 Pocket Computer PC-1'' –

Sharp PC-1211 The Sharp PC-1211 is the first pocket computer ever released, marketed by Sharp Corporation in March 1980. The computer was powered by two 4-bit computing, 4-bit CPUs laid out in power-saving CMOS circuitry. One acted as the main CPU, the other dea ...

* ''TRS-80 Pocket Computer PC-2'' –

Sharp PC-1500 The Sharp PC-1500 was a pocket computer produced by Sharp between 1981 and 1985. A rebadged version was also sold as the TRS-80 Pocket Computer PC-2. The whole computer was designed around the LH5801, an 8-bit CPU similar to the Zilog Z80, but ...

* ''Tandy/TRS-80 Pocket Computer PC-3'' –

Sharp PC-1251 The Sharp PC-1251 was a small pocket computer that was also marketed as the Tandy Pocket Computer. It was created by Sharp Corporation in 1982.Casio PB-100 * ''Tandy Pocket Computer PC-5'' – Casio FX-780P * ''Tandy Pocket Computer PC-6'' – Casio FX-790P * ''Tandy Pocket Computer PC-7'' – Casio FX-5200P * ''Tandy Pocket Computer PC-8'' – Sharp PC-1246

Purpose

Pocket computers were an advancement over early

programmable calculator Programmable calculators are calculators that can automatically carry out a sequence of operations under the control of a stored computer programming, program. Most are Turing complete, and, as such, are theoretically general-purpose computers. ...

designs. In addition to providing users with scientific math functions in a small portable package, the devices also understood a form of the

BASIC programming language 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), a 2003 film * Basic, on ...

. They included a

QWERTY QWERTY ( ) is a keyboard layout for Latin-script alphabets. The name comes from the order of the first six Computer keyboard keys#Types, keys on the top letter row of the keyboard: . The QWERTY design is based on a layout included in the Sh ...

keyboard Keyboard may refer to: Text input * Keyboard, part of a typewriter * Computer keyboard ** Keyboard layout, the software control of computer keyboards and their mapping ** Keyboard technology, computer keyboard hardware and firmware Music * Mus ...

, of either rubber capacitive or membrane type, to use for entering the names of scientific functions and programming commands, in addition to a traditional

numeric keypad A numeric keypad, number pad, numpad, or ten key, is the calculator-style group of ten numeric keys accompanied by other keys, usually on the far right side of computer keyboard. This grouping allows quick number entry with right hand, ...

. (The exception was the PC-7, which had a rectangular and alphabetically ordered keyboard, like most scientific calculators.) On some models, the

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 ...

keypad had a different type, form factor, and location than the numeric keypad.

Design

The models provided a short one-line

dot-matrix A dot matrix is a 2-dimensional patterned Array data structure, array, used to represent characters, symbols and images. Most types of modern technology use dot matrices for display of information, including mobile phones, televisions, and pri ...

LCD A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers to display information. Liquid crystals do not em ...

display, to show the current line of input text, or a segment of it containing the cursor. Character widths in these models varied from 12 characters in the PC-4 and PC-7 to 24 characters on most of the rest. The displays also included some way of indicating operational mode, scientific mode, and other states and conditions. The Casio models included lower-case characters. These were only for use in PRINT statements, as lower-case commands and

variables Variable may refer to: Computer science * Variable (computer science), a symbolic name associated with a value and whose associated value may be changed Mathematics * Variable (mathematics), a symbol that represents a quantity in a mathemat ...

were not accepted as with almost all BASIC programming machines. In general, the two specific lines were not cross-compatible, but there were compatibilities within lines. PC-1 programs would work unmodified on the PC-3 and on the PC-8 with changes for screen size, and PC-4 (26-3650B) programs would run unmodified on the PC-5, PC-6 and PC-7. The PC-2 was a unique architecture and was the only unit in the line allowing direct memory access with POKE, PEEK and CALL.

Operating modes

Each model had two operating modes: Run and Prog.

Run

In Run mode, the

command line A command-line interface (CLI) is a means of interacting with software via command (computing), commands each formatted as a line of text. Command-line interfaces emerged in the mid-1960s, on computer terminals, as an interactive and more user ...

could be openly used to execute one-line, non-BASIC operations. This is the normal mode used, from where arbitrary

calculation A calculation is a deliberate mathematical process that transforms a plurality of inputs into a singular or plurality of outputs, known also as a result or results. The term is used in a variety of senses, from the very definite arithmetical ...

s could be entered to receive results. The Run mode also allowed the

execution Capital punishment, also known as the death penalty and formerly called judicial homicide, is the state-sanctioned killing of a person as punishment for actual or supposed misconduct. The sentence ordering that an offender be punished in ...

of the BASIC programs stored in the device. Instead of an "equals" key to initiate calculation evaluation, an "EXE" (execute) key was provided. This caused confusion with those who were used to traditional calculators. The = character was used only for variable assignment, and evaluation tests in programs. The input of simple calculations would be aggregated on the command line, and no results would be displayed until the EXE key was pressed. In some models, a special ANS variable was provided to reuse the results of the previous calculation; in others, the previous calculation was automatically included if the next calculation began with an operator. Some valid calculation input examples (PC-8): SIN40 10+2+(8*1)/7 TAN (LOG (√(4/3)))

Prog

The Prog mode changed the input from a command line to a program editor. In this mode, BASIC programs could be entered one line at a time. Up and down arrow buttons were provided to scroll up and down through the program space. On most models, free calculations could not be entered in the Prog mode. Certain models, especially the Casio-derived ones, called this mode WRiTe mode. On the Sharp models, there was only one

line number In computing, a line number is a method used to specify a particular sequence of characters in a text file. The most common method of assigning numbers to lines is to assign every line a unique number, starting at 1 for the first line, and increm ...

ing space. In order for multiple programs to exist on the device, they had to be written in different ranges of line numbers. For example, it was common to insert one program starting with line 100, and another program starting at line 200, etc. Valid line numbers in most models were from 1 to 999. To prevent run-on execution, each program had to finish with the END command, unless run-on execution was desired. On Sharp-derived units, labels could be inserted into the program, usually single characters such that in Run mode, that program could be executed by depressing a special DEF key followed by the key of that character. This was equivalent to an explicit GOTO command to the first line number of that section of program, which was also a valid way to execute programs from Run mode. In the Casio-derived models, the BASIC space was subdivided into segmented program spaces which could be numbered, cleared and executed manually, or could call each other. Many of the devices included a special

modifier key In computing, a modifier key is a special key (or combination) on a computer keyboard that temporarily modifies the normal action of another key when pressed together. By themselves, modifier keys usually do nothing; that is, pressing any of the , ...

to expedite the entry of BASIC commands as well as scientific function names. The most common commands would each be associated with a key, and the full command could be entered by depressing the special modifier key, followed by the associated key for the command. In some models, BASIC and other commands would be converted into one-character tokens (converted to strings upon display) instead of being stored as whole strings.

Memory

The total memory capacity of the devices varied from 1 KB to 12 KB and up as far as 16 KB with the use of an available

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card (only for some models). The optional RAM cards varied in sizes from 1 KB, 4 KB and 8 KB. All user storage was taken from the same space, so allocation of arrays using DIM would decrease the available memory for program instructions, and vice versa. However, the storage space for one-character alphabetical variables was pre-allocated, and as a result the A

array An array is a systematic arrangement of similar objects, usually in rows and columns. Things called an array include: {{TOC right Music * In twelve-tone and serial composition, the presentation of simultaneous twelve-tone sets such that the ...

had special significance in many units. For example, in the PC-8, the A array actually pointed to the locations of the alphabetical variables, so A(2) pointed to the value of B, and so on. As a result, published programs for the device avoided the use of A as either an array or an alphabetical variable. On some models the entire variable space could be manipulated in this fashion.

Other notes

It was not possible to define new

mathematical Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...

function commands for use in Run mode. However, on many Sharp derived models, a special AREAD command was added to BASIC which would assign the current value on the display line to a given variable, which could then be used in a program. Combined with a defined key, this allowed very quick custom operation. The program interpreter on the models did not provide human-readable

error An error (from the Latin , meaning 'to wander'Oxford English Dictionary, s.v. “error (n.), Etymology,” September 2023, .) is an inaccurate or incorrect action, thought, or judgement. In statistics, "error" refers to the difference between t ...

information. Errors encountered either in program execution or calculation evaluation would be returned as one of 9 error codes, usually indicated by replacing the display with text such as "ERROR 4". On the PC-7 model the list of error codes was printed above the text keypad, and was included on the case of the PC-8, but with other models users not familiar with the meaning of each code would have to refer to the manual. Like other characteristics of this line, the meanings of the error codes were not necessarily equivalent from model to model.

Undocumented commands

The PC-3 and PC-8 had a couple of commands that were not listed in the manual, but nonetheless were recognized by BASIC and usable. * ; and - the highest memory location is 2047, and it is possible to modify the BASIC program in RAM directly with , as well as access a certain memory location (37, possibly?) that controls the DEG/RAD/GRAD spots on the LCD. With judicious POKEs into the BASIC program text area more characters in the PC-8 character set can be discovered, including a `tilde` which also seems to function as a bizarre command. Some blank characters when 'ed will display additional symbols on the printer if one is attached. * - seems to be some type of test mode for the display. Will show a couple of patterns on the LCD and then appear to lock up. * - seems to be some type of test mode related to the optional Printer Interface Also, SHIFT-6 on the PC-8 will display a

Yen The is the official currency of Japan. It is the third-most traded currency in the foreign exchange market, after the United States dollar and the euro. It is also widely used as a third reserve currency after the US dollar and the euro. T ...

symbol.

References

External links

Tandy Pocket Computers at the Pocket MuseumFloodgap Retrobits Tandy! Pocket! ManiaSharp PC-1500 computer (TRS-80 PC-2) resource page
- much documentation.
All and more about the Sharp PC-1500 computer (TRS-80 PC-2)
{{Authority control Computer-related introductions in 1980 Pocket computers TRS-80 RadioShack