13 Jun
2010
13 Jun
'10
1:51 p.m.
Are there any HP80 seires experts here? I've got a curious quesiton.
I am looking at the HP82909 128K RAM module (for the HP86/87 series).
There are several places on the PCB that are not used -- from memory,
thre are 4 locations for 14 pin ICs. More curiously, there's a place for
a rssistor and transsitor to drive the ROMDIS/ line on the computer
connector.
I am pretty sure the 'missing' chips are simple logic functions. One is
very probably a '74. Another may well be a '30. But I haven't worked out
the details yet.
My guess is that some HP product actually used this extra logic. So my
'curious quesiton' is : What product was it?
-tony