The Model 4
Tandy made several improvements to the Model III and introduced the Model 4 in 1983. The Model 4 looked just like a Model III and was completely Model III compatible, but had extra features that were used by its native operating system, TRSDOS 6. These features included a full 64K of RAM plus support for another 64K of extended memory, an 80 by 24 screen, reverse video, and a 4Mhz clock speed. This time, instead of writing the operating system in-house, Radio Shack contracted with Logical Systems (the authors of LDOS) to write TRSDOS 6. The result was a version of TRSDOS that was quite similar to LDOS, and which became very highly regarded. Radio Shack also sold CP/M for the Model 4, as did several other companies. The Montezuma Micro CP/M was regarded by many people to be the best. DOSPLUS and MULTIDOS were also sold in new Model 4 versions, but were never as popular as LS-DOS or CP/M.
The Model 4P, a transportable Model 4, was introduced in 1984. It could run the same programs as a desktop Model 4, but could be transported in its own carrying case. The Model 4P lacked Model III ROMs and cassette support. The final member of the Model I/III/4 line, the Model 4D, was released in 1985. It came standard with double sided drives, was bundled with DeskMate integrated software, and had a few other minor changes. Radio Shack continued selling the Model 4D for several years, until it was finally discontinued.
Filed Under Computers
Comments
Comment by Terry Stewart:
Matthew,
Have just enjoyed a pleasant hour browsing through your ever-expanding site. Good stuff!
Pity Model 4s are so rare here in New Zealand. I’d love to add one to my collection!
Comment by Ron Schwarz:
Ah, memories… my hotrodded Mod-1 (went through about TWENTY trips to Texas - they kept extending the warranty after each month or so it spent there — many times, I’d fire it up in the store when I went in to pick it up — it would lock up inside of ONE MINUTE of turning it on — and straight back it went. Mine was the third TRS-80 sold in my county in rural Michigan — I consider myself a paying ALPHA-tester, argh!
I cut my teeth on that thing — developed software to manage our wholesale camera repair shop — and ended up writing about VB programming after my health went in the toilet. (My health is now pretty much completely shot, and the industry has gotten so far away from me that I’d never catch up.)
I ran a BBS (”Town Crier”) on a Model 4P with the 300b Infernal Modem — hey, it worked :) (Especially after I recoded the editor portion :)
My Model 1 gave up the ghost eventually — died under the knife, so to speak. The Mumford Micro clock-speedup kit was more than it could handle. The smoke didn’t come out, but the machine was definitely dead, for keeps. A pity. Ah, the memories of my IDS printer (sounding like an advancing army) banging off invoices and repair quotes… and the lower case mod I soldered in (piggyback 21L02 and some surplus calculator keys, and a driver that Dennis Bathory Kitz wrote) made “word processing” somewhat usable too.
We ran out and bought a Model 4, to be able to keep running our business — the power supply died shortly after the warranty expired, so I bolted in a big honker of a linear supply to the floor of the cabinet — worked great. Pulled out the two SS drives and installed FOUR 720K half-height drives (80 tk, DS/DD). Wow, SO much storage! :)
Those were the days. We’re really spoiled now.
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