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Tandy Radio Shack

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.


Model III configurations, by Dave Thompson:
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).

Brandt Daniels adds:
There was also a TRS-80 VideoTex Computer terminal in 1980.

Mark Fowler reports:
I worked for a company in 1982 that had integrated a 5MB, and later a 10MB hard disk into the TRS80 Model III. It was then programmed in FORTRAN-66 as a dedicated medical records system, to mimic the pegbook accounting system in use in the 1980's. We introduced green phosphor, and later amber phosphor display tubes. Some systems were used with a modem to do simple email-type applications, and to access various bulletin boards.

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In 1983, I worked on one of these for a Radio Shack store that also rented VHS movie tapes. It was a 48k dual floppy machine with a printer attached. My mission was to write the BASIC software necessary to inventory and keep track of which movies were currently rented out. It also printed out the tapes that were available for a given month. I got this job because I had experience with Level II BASIC on the Model I machine. Great times! :)

Friday 26th December 2014
Chuck Rose (Vermont, USA)

At school we had the model I and the TRS80 model III was my first own computer. I still have it and it is still working and I also have lots of original documentation and tons of floppies. As I bought it once in Germany it has an extremely rare feature: German keyboard layout! So I''m very proud to have it $-) Would be happy to share memories about this machine if you like:

Wednesday 20th August 2014
Johannes (Switzerland)

My parents bought me a TRS-80 Model III as a high school graduation present in 1981. That was a sweet machine at that time. Of course, I didn''t have floppy disks because those were too expensive. OTOH, I did have the new *triple speed* audio cassette that could load data at a zippy 1500 bits per second!

I quickly outgrew the 16K of RAM and upgraded first to 32K and then maxed out at 48K. I still have the machine, and I still have the Model III ROM Commented book that has the assembly source code for the L2 ROM.

Not seeking to sell...just posting for shared interest. :-)

Wednesday 4th June 2014
Scott (USA)


MANUFACTURER  Tandy Radio Shack
TYPE  Home Computer
YEAR  1981
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
PRICE  No disk model : AU$1450 (Australia, 1981)
$2495 in 1984 for a complete system with 2x360 KB drives, TRSDOS, 64kb Ram, software and printer

Software for this system!

1980 Big Five Software
1979 Microsoft
1980 Big Five Software

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