|Heath/Zenith Z90, ca. 1981|
|CPU:||Z80 @ 2MHz|
|Floppy Drives:||2 Teac FD-55F-030U quad-density (720KB each)|
|Display:||12" Green (25x80)|
|OS:||CP/M 2.2 or HDOS|
This system has a double-density controller (Z-89-37), and an additional 16KB memory board (85-2359-1) to take it to a full 64KB. It echoes characters perfectly in offline mode, but the processor board doesn't appear to work at all.
Update (09/14/2014): On checking voltages, I found that the -12V line was down close to -1V. I traced that to a shorted 2.2uf tantalum capacitor (C511) and replaced it, along with several other tantalum caps on general principles. The -12V line now looks good, but the CPU board is still not initializing properly.