Wang 700 ROM
Next Log Entry
Reading and Recovering Microcode
The ROM was removed for specific inspection and appeared to be undamaged. It is version P6B with a date stamp of June 2 1971, nearly two years after the introduction of the 700 series. It’s interesting that the rest of the machine has date stamps of June 1970, perhaps this P6B ROM was a replacement. Other ROM versions known for 700A machines are P3A and P4A which may have been earlier versions that were replaced by P6B.
This P6B ROM has 24 of a possible 32 rows of diodes populated, allowing a maximum of 1536 address wires to give a total capacity of 1536 x 43 = 66048 bits or 8.25k bytes.
Reading the ROM
DoPECC is keen to preserve the Wang microcodes and the DoPECC ROM reader can read Wang Wire Braid ROMs in a stand alone manner.
Attempts to read this ROM have not given stable results, it will need further investigation and perhaps re-trimming of component values to compensate for drift over the past fifty years.
In the meantime a ROM emulator will be used to continue the restoration of the main machine.
