Looking for info on National Semiconductor RAM board (VAX 11/730)
ard at p850ug1.demon.co.uk
Sat Jun 20 09:40:15 CDT 2015
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.
It's a hex height DEC-type board with the ejector handles. Connections to fingers on A and B as you
might expect, also the grant continuity strapping on C and D, grounds on D (only) and a couple of signals
on C (I've not figured out what yet).
The only identification I can find on it is in the etch :
PWB 551109464-002 B
(I assume the first is the part number for the bare PCB, the second for the stuffed board)
There seems to be one RAM too many!. The main RAM array is 4 rows each of 32 4164-like DRAMs.
There is a second block of 28 such DRAMs, presumably 7 bits for each row of the main array to
provide the ECC bits. And then a further single RAM off to one side. The DEC MS730 doesn't seem
to have this, and I wonder what on earth it is for.
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.
Does anyone recognise this board?
A related point, I am thinking of removing the TSU05 from my 11/730 and putting an expansion
box in place of the tape drive in the rack. In which case I can install this memory board. Is 5MBytes
(the maximum an 11/730 can take) worth having over 4MBytes?
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