2 Mar
2008
2 Mar
'08
12:42 p.m.
If it helps any, there are usually two numbers (at
least) on the HP PCBs, one
in foil and one in ink, the foil number specifies the foil pattern, the ink
number specifies the component population.
I've also seen HP PCBs with an official lable stuck over the etched part
number to specifiy different compoenns fitted. A classic example of this
would be the microcode board in an HP9100. This is the board with the
core-on-a-rope ROM on it, it's the same PCB in a -A and a -B, but
different ROM 'programming'. The etched number is for the 'A version, the
board in every -B machine I've seen ahs a label stuck over it. Or a PCB
used for a ROM modele, the srtuck-on label depending on which ROMs are
soldered to the PCB.
Mind you, sometimes there are different PCBs that differ only in the
etched part number (!). The ROM boards in a 9810 and 8820 (2 boards in
the latter) are the same electically. They're the same connections to the
edge fingers, they take the same type of chips (8 HP custom ROMs) and
have the same tack layout. The only differece between the 3 boards is the
etched part number, and etched numbers saying what ROMs go where and what
chip select line drives them .
-tony