20 Jun
2015
20 Jun
'15
7:58 a.m.
[Argh! Following up my own post :-(]
I am looking for any information on a National
Semiconductor RAM board that I think goes in
a VAX 11/730. My 11/730 (which admittedly I have not run) has 2 DEC MS730 boards and 2 of
these
NatSemi boards, I found another one while unpacking stuff today.
[...]
The only identification I can find on it is in the
etch :
PWB 551109464-002 B
PWA 980109464
[...]
There seems to be one RAM too many!. The main RAM
array is 4 rows each of 32 4164-like DRAMs.
Rest of the board is TTL drivers, etc. There are 2
LEDs, one green, one yellow. And a momentary pushbutton
switch. I have no idea of the functions of those.
That switch may well be latching (alternate action). I wasnt't pressing it hard
enough. It seems to be
wired directly to the yellow LED (amongst other things).
I have found a mention of this board in an 11/750 FAQ (not surprising, I think the same 1M
boards can
be used in the 11/750 and 11/730). It appears that in normal operation both LEDs are on.
Pressing the
button turns off the yellow LED and completely disables the board. Quite why you'd
want to do this I do
not know...
Oh, and it mentions a 'spare RAM chip in a socket on the board'. All RAM on my
board is, indeed, socketed.
If this is just an unused chip to substitute if one fails then I think I've seen it
all...
-tony