Trs-80 Model III

08/06/05

This is the first computer I ever worked on. It was in the eighth grade and I love it. I was so "Star Trek" with it's self-contained monitor, keyboard and disc drives. In fact, a Star Trek game was the very first computer game I ever played. You would plot where the Enterprise would go and you would see these ASCII graphics representing the Enterprise and Klingons. Greatness. I see them on E-bay, and I have been tempted to buy one, but where would I put it and how would I explain it to my wife. If I could find a non-working one, I would like to install a real computer into. Boss.

The model 3 is generally regarded as the successor to the Model 1. Its two 5.25" floppy disk drives could convert model 1 disks.

Initially Radio Shack wanted to sell both the model 1 and 3 at the same time, but the FCC forced them to stop selling model 1. Is so they were discontinued because of the excessive radio noise that they put out.

However, the Model 3 wasn't FULLY compatible with the model 1. There were differences in ROM which meant some programs had to be converted, especially those machine language ones that made ROM calls.

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Dave Thompson adds:
TRS-80 Model III was sold in multiple configurations.
No hardrive configurations included:
Model III with Level 1 ROM, 8k RAM sold for US$799. Model III with Level 2 ROM, 16k RAM sold for $999.
The first floppy drive cost $849, and could store 168k. The second drive was cheaper, and could store more. The price difference is due to the first one included the drive controller. The increased space on the second drive (189k) was due to the first drive must also contain some TRS-DOS (the operating system).

NAME	TRS 80 MODEL III
MANUFACTURER	Tandy Radio Shack
TYPE	Home Computer
ORIGIN	U.S.A.
YEAR	1981
END OF PRODUCTION	Unknown
BUILT IN LANGUAGE	TRS-80 Level II BASIC
KEYBOARD	Full-stroke keyboard with separated numeric keypad
CPU	Zilog Z80 then Z80A
SPEED	2.03 MHz
RAM	16 KB (up to 48 KB)
ROM	14 KB
TEXT MODES	32 or 64 columns x 16 lines
GRAPHIC MODES	128 graphic characters
COLORS	monochrome
I/O PORTS	Tape (500 or 1500 bauds), Centronics, RS232
BUILT IN MEDIA	Zero, one or two 5.25'' disk-drives.
OS	TRS DOS (other OSes were available : New DOS, LDOS, MultiDOS, ...)
POWER SUPPLY	Built-in power supply unit
PERIPHERALS	Various Tandy peripherals

The Model III

As a follow on to the Model I, in July 1980 Tandy released the Model III, a more integrated and much improved Model I. The improvements of the Model III included built-in lower case, a better keyboard, and a faster Z-80 processor. With the introduction of the Model III, Model I production was eventually discontinued as the Model I's did not comply with new FCC regulations regarding radio interference. In fact, the Model I's radiated so much RFI (Radio Frequency Interference) that many game companies made their games so you could put an AM radio next to the computer and use the interference to get sounds.

Trs-80 Model III

This site was last updated 08/06/05