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TRS-80 Model III

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Early Intel and Zilog CPU

based portable personal



TRS-80 Model I

TRS-80 Model III

TRS-80 Model IV

Color Computer

Color Computer 2

Color Computer 3



Early ultra-light personal

computers based on Intel

and Zilog CPU's.  These

units are all unique in

their class.

TRS-80 Model II

Tandy Model 12

Tandy Model 16, 16b



Once again systems

caught between CPU


TRS-80, Tandy 2000

Tandy 1200

MC 10



Simply the best personal

computers built. 

Operated under MS-DOS

2.11 to 6.22.  Based on

the IBM PC. Jr.

Tandy 1000, 1000a

Tandy 1000SX ,1000TX

Tandy 1000 SL,TL & TL2

Tandy 1000EX, 1000 HX

Tandy 1000 RL, RLX

Introduced: July 1980
CPU: Zilog Z-80, 2.03 MHz

RAM: 48K
Ports: Tape (500 or 1500 bauds),

Parallel & RS232
Display: 12" B/W monitor built-in: 16

X 64 text
Storage: Two internal 178K floppy

drives, External hard drive

Operating System: TRS-DOS.

The TRS-80 Model III is essentially

the Model I integrated into one

complete unit, with all the upgrade

features that Tandy added to the

Model I in their subsequent release.  It is probably Tandy most popular personal / business

computer in the TRS-80 line.  Although designed for the business market, the Model III

has to it's credit an impressive collection of games.


The Model III has a 16 x 64 character display using a CRT very similar to the RCA picture

tube from a 12" television.  The starting unit came with 16K RAM, and two single sided

5.25" floppy drives.  Tandy built the computer with a daughter connector on the main

board to upgrade the unit for hi-resolution graphics.  Edge card connections were provided

for external floppy drives, and parallel printer.  The serial port was optional.


A few clones were built based on the Model III which were very successful in the business

market. Tandy provided a version of TRS-DOS, but the superior operating systems were

LS-DOS by Logical Systems or NEW-DOS 80.  Clones were produced by LNW Corporation,

Sanyo, MTI Corporation and Adcock & Johnson to name a few.



The above images from left to right are:  (a) Model III Clone from MTI, (Microcomputer

Technology Inc.)  These units hit the business market and could be seen in may video

store operations.  Bundled as a canned solution for video rental, the MTI held until the

late 1980's.  (b) The LNW-80 with a color composite monitor.  This unit was prevalently

based on the CP/M operating system.  The original was introduced as a TRS-80 Model I

clone, the specifications were a 4Mhz., Z80A CPU, with Hi-Rez color graphics of 480 x

192, and could support full 80 column display this unit was complete with dual 5.25'

double sided floppies.  (c) LNW-80 with it's green phosphor 80 column display without the

5.25" floppy modification.



Images from top to bottom - Left to Right:  TRS-80 Model III, MTI Modified Model III, LNW-

80 w/ Drive Option and the base LNW-80.



(c) 2004, 2005 Brian K. Hahn

 All Rights Reserved.