13 Jun
2007
13 Jun
'07
2:47 p.m.
Anyway, from what I remeber, the controller card
is based round a 6802
processor [1]. The actual disk contorller chip, anohter 40 pin device, is
made by Fujitsu, and has the same pinout as the 1793 _apart from being
+5V supply only_.
[1] If you've got chips marked with the HP house codes (1820-xxxx
numbers, maybe soem 1818-xxxx ones), let me know what they are and I can
see if I can find the standard equivalents.
Many chips on my controller have only HP house codes.
In particular, there are three 40 pin chips, with codes: 1820-2099, MB8866 (this has an "F" as logo, may be it's
Fujitsu or Fairchild, I don't know),
and an Intel D8291A.
8291 = HPIB interface chip (also not a house-code)
Then there are four smaller chips (24 pins? I
didn't count them...) marked:
1818-1834 and 1818-1835 (these are on sockets: may be they are roms?), and
I think those are the firmware ROMs
two 1818-0701.
1818-0701 = MCM68A10P 128 byte static RAM
Then, the smallest chips (14-18 pins) with hp house
codes are:
I'll fill these in on the same lines
1820-2075 = 74LS245 (that has 20 pins, surely)
1826-0210 = LM361
1820-1197 = 74LS00
1820-1216 = 74LS138
1820-1202 = 74LS10
1820-1112 = 74LS74
1820-1422 = 74LS122
1820-2058 = MC3448L (HPIB buffer chip)
1820-0325.= MC815P
[...]
This might come
from the main PSU, but on at least one HP controller, it
was producaed by a charge pump circuit clocked from a divided-down
version of a master clock. That might be worth looking for and checking.
I've checked almost all points in the circuit, and I didn't find any -Ve
supply. Also, PSU only gives +5 and +12 volt.