TRS-80 Model I

TRS-80 Model I from 1978

CPU: Z80 @ 1.77MHz
Display: 12" white CRT monitor (26-1201)
Ports: video, cassette, power, expansion interface
Catalog No.: 26-1006
Serial No.:
Catalog Price: $789
Notes: This unit has had several modifications installed: there are 4 switches (2 pushbutton and 2 toggle) added to the case. The upper left pushbutton is another Reset Button. The lower left pushbutton appears to be a Control key (Shift/Down-Arrow). The toggle switches are for a lower case modification. The system was not quite working when I got it: the video didn't sync. It turns out that there was a bad inverter in both the horizontal and vertical sync circuits. After I replaced two 74C04 chips (Z6 and Z57), it works fine.

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Last updated on Tuesday, July 22, 2014