TRS-80 MC-10

The TRS-80 MC-10 microcomputer is a lesser-known member of the TRS-80 line of home computers, produced by Tandy Corporation in the early 1980s and sold through their RadioShack chain of electronics stores. It was apparently designed as a low-cost alternative to Tandy's own TRS-80 Color Computer to compete with entry-level machines that had previously dominated the market, such as the Commodore VIC-20 and Sinclair ZX81.

The TRS-80 MC-10
Release date1983 (1983)[1][2][3]
Introductory priceUS$119.95 (equivalent to $307.91 in 2019)
Discontinued1984
Operating system8 KB (8192 bytes) (Micro Color Basic, developed by Microsoft) in ROM
CPUMotorola MC6803 @ 0.89 MHz
Memory4 KB (4096 bytes) on-board, expandable to 20 KB (20,480 bytes) via external expansion pack
GraphicsVDG: MC6847
Input48-key "Chiclet"-style keyboard
Power8V AC 1.5A
Dimensions8.5" x 7" x 2" (216mm x 178mm x 51mm)
Mass29.05 ozs. (836.32g)
The TRS-80 MC-10
The Matra Alice, a derivative of the original MC-10

Due to its limited feature set, the MC-10 was of value primarily to hobbyists and as an introduction to computer programming. It was not a commercial success and was discontinued only a year after its introduction.

A clone of the MC-10, the Alice, was marketed in France through a collaboration among Tandy, Matra and Hachette.

Description

About the size of a hardcover book, the MC-10 came equipped with four kilobytes (4096 bytes) of RAM, a Motorola MC6803 eight-bit microprocessor, a built-in serial port, and graphics capabilities similar to those of the original Color Computer (provided by the same MC6847 video display generator).

Like most early home computers, the MC-10 included a BASIC interpreter in ROM and used regular audio cassettes for bulk storage. Text and graphics were displayed on a television set via a built-in RF modulator. Less common for machines in its class was the integrated RS-232 serial port, which allowed the MC-10 to use a wide variety of line printers and modems without additional hardware.

Even so, at the time of its release in 1983, the MC-10's specifications were underwhelming. Disk drives, full-travel keyboards, medium-resolution graphics, and complete 64-kilobyte (65,536 bytes) memory banks were becoming popular features for home computers; the MC-10 offered none of these, severely limiting the functions it could perform and the range of users to which it could appeal.

The MC-10 was discontinued in 1984, along with the 16 KB (16,384 bytes) memory upgrade and small amount of cassette-based software that had been released for it. It never achieved a wide following.

Specifications
  • VDG: MC6847
    • Text: 32×16
    • Low-res: 64×32, 8 color (4bpp)
    • Low-res: 64×64, 4 color (2bpp)
    • Med-res: 128×64, 2 color (1bpp)
    • Med-res: 128×64, 4 color (2bpp)
    • Med-hi: 128×96, 2 color (1bpp)
    • Med-hi: 128×96, 4 color (2bpp)
    • Hi-res: 128×192, 2 color (1bpp)
    • Hi-res: 128×192, 4 color (2bpp) (partially supported, insufficient video RAM)[4]
    • Hi-res: 256×192, 2 color (1bpp) (partially supported, insufficient video RAM)
  • I/O Ports:
    • RS-232C serial interface (300-9600 baud; 600 baud from BASIC)
    • Cassette interface (1500 baud)
    • Internal RF modulator
    • Memory expansion interface

Although the memory expansion interface connected directly to the CPU bus and could have been used for many applications, the edge connector involved had an unusual number of pins and was difficult to obtain.

The RS-232C serial interface had extremely limited usefulness. Although the 6803 CPU conveniently includes a built-in UART, it was not connected to and did not assist the RS-232C interface in any manner. In part, this was because a single 3.58 MHz TV colorburst crystal was used to generate video and clock the CPU, and this clock rate did not correspond to any standard baud rate when divided for the UART. As a result, programs had to shift all bits individually into and out of the RS-232C interface, creating artificial and especially critical timing considerations.

The cassette interface had similar difficulties, plus a few. Although Micro Color Basic included an undocumented CLOADM command for loading machine-language programs and an undocumented VARPTR function for manipulating variables as memory, there was no corresponding CSAVEM command (documented or otherwise) to permit machine language programs to be saved to tape.

Software

A limited amount of software was available on cassette for the MC-10, including Lunar Lander, Checkers, and a machine-language Pinball program. However, as most programs written in Basic for other TRS-80 models were compatible with the MC-10, many books with BASIC programs were available for the user who was willing to type in the code.

Retrocomputing hobbyists have created many games that were improvements to those released officially.

  • TRS-80 Model MC-10 Original Box
  • TRS-80 Model MC-10 Ports
  • TRS-80 Model MC-10 16K RAM Expansion

References
  1. The TRS-80 MC-10: too little, too late for too much?, (evaluation) By Owen W. Linzmayer, CREATIVE COMPUTING VOL. 9, NO. 10 / OCTOBER 1983 / PAGE 39
  2. TRS-80 MC-10 'battles' T/S 2000, By Scott Mace, Page 3, InfoWorld, 20 Jun 1983
  3. New Systems, Hardware News, Page 46, InfoWorld, 8 Aug 1983, The TRS-80 Micro Color Computer Model MC- 10 from Radio Shack is aimed primarily at first-time computer buyers.
  4. TRS-80 Micro Color Computer Model MC-10 Service Manual, Radio Shack Corporation, Catalog Number 26-30-11, Pages 4-6, 17.
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