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TANDY RADIO SHACK
TRS-80 MICROCOMPUTER or TRS-80 Model 1
UNIT SOLD = 200,000
Click me to enlarge!
In 1963 Charles Tandy buys the Radio Shack Corporation, for free.
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TRS (Tandy Radio Shack) An early Tandy trade name. In 1977, the TRS-80 was one of the three first personal computers. TRS-DOS was its operating system.
  • Catalog Nunber; 26-1006
  • SN; 096879
  • CPU; Z80
  • Ram; 16K
  • Level II Basic in ROM
Click here to view a 1977 Radio-Shack ad.
In Dec. 1976 Don French and Steve Leininger are given official blessings to
           develop a microcomputer for Radio Shack.
In Jan. 1977 A working model of the first Radio Shack computer is demonstrated to company president, Charles Tandy.
At the time the only home computers available to the general public were things like the Altair kits.
In Aug. 1977 Radio Shack, announces the TRS-80 microcomputer, with Z80 CPU, 4KB RAM, 4KB ROM, keyboard,
           black-and-white video display, and tape cassette for US$600.
The Model 1 was first made available with a 4 kilobyte tiny BASIC in ROM, and either 4 or 16 kilobytes of RAM. The CPU board of the computer was contained in the keyboard unit, and it used a separate black and white monitor.
The monitor was really a RCA black and white TV without the TV tuner.
The Level 1 BASIC was very limited. There were 26 integer variables available, A through Z, one single dimension integer array, and one or two string variables.
Later, the ROM was upgraded to a 12K "Level 2" BASIC, which was much more advanced. Level 2 BASIC was actually useful to write real programs in, though all it supported for storage of programs and data was cassette tape.
Level 2 BASIC and 16K of RAM became the "standard" configuration.


To get real use out of the Model 1, you needed the Expansion Interface which would let you go above 16K of RAM to 32K or even 48K.
It also had a provision for using two cassette tape units, a printer port, the floppy disk controller, and a serial port. Cassette deck
.
Floppy disk drive

  Finally, it supplied the processor with a real-time clock interrupt that was used by the various DOS systems
(and a couple of cassette based ROM enhancements) for time keeping functions.
Click on image to enlarge
Microsoft had a Level III BASIC that loaded from cassette and made several useful additions to the standard BASIC.
The main problem with the machine was the interconnection between the keyboard and the expansion interface. It used a 40 conductor ribbon cable, and the connectors would get dirty quickly. There was nothing more frustrating than to have a large program typed in only to have the machine decide it wanted to reset itself. The other problem was flakey connections at the serial port board. All these contributed to the name "Trash-80". The interconnect problem was bad enough to give rise to several companies that sold gold-plated connectors that could be soldered to the machine.


Click here for a brief history of Radio Shack Computers.

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