Wang 700 First Power Up Next Log Entry

No smoke, display lights but not functional

The machine was now known to have good power supplies and so the PCBs could be reloaded for a first test of the complete logic engine.

Wang 700A First Prime

The microcode ROM was under suspicion due to unstable behavior on the ROM Reader and so it had been replaced with a DoPECC ROM Emulator. This was the first use of the Emulator in 700 Series mode but the emulator had been shown to produce correct data when used with the DoPECC ROM Reader.

The first power up was successful in that no smoke or sparks came out. One Nixie in each display lit up after pressing Prime but there was no calculator style display and the keyboard was non-responsive. Pressing the four microcode restart buttons (Prime, Verify Prog, Set PC, Record Prog) gave consistent responses with single Nixies lighting up and no other function.

Wang 700A First Record Prog

Since all machine functions depend on complete and correct microcode execution, the typical symptom from almost any malfunction is a non-responsive machine perhaps with random Nixies alight. There is not much more diagnostic information to be gained from the behavior of the machine.

Troubleshooting has to determine if the problem is the ROM not delivering correct microcode, or the logic engine not correctly executing the code. This pretty much requires the application of a Logic Analyzer to monitor microcode flow and logic engine responses.

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