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unidentified ram card

I

Isaksson

New Member
Joined
Oct 5, 2020
Messages
6
Hi all
my first post here

bought me an IBM 5150 and this card sat in it, can not find any info. online and I want to expand the memory on the card to 384kb so that I get a total of 640kb in the machine, but to succeed with this I need to install ram chips and know how to set the jumpers correct.
anyone have any info regarding this card? or how to set the jumpers?

https://drive.google.com/file/d/1yVKE-a45olOA4PyF7o8AeqH69gURteek/view?usp=sharing
https://drive.google.com/file/d/1yQ_T6_AEkOzhLbMtE-rHcODf4KNiYJO3/view?usp=sharing
 
Interesting board. Is there anything printed or labelled on the rear of the card?

Also, curiously, there is no spot for an RTC battery. Seems a bit strange to have an RTC chip without a battery, as that wouldn't be particularly useful.
 
kdr said:
Also, curiously, there is no spot for an RTC battery. Seems a bit strange to have an RTC chip without a battery, as that wouldn't be particularly useful.
Click to expand...

I believe I see a spot for one, mounted vertically in the blank space to the left of the 8250. Looks like one of the longer packages, stack of N cells or something.
 
Ah yes, looking again I do see the plated holes where a battery or holder would be installed.

I had a browse through TH99 just in case there was a similar board in the database, but no such luck.

OP: my guess would be that those labelled chips in the top-right corner are the address decoders (some sort of PAL device?) - perhaps you could carefully remove the labels and see if the chips can be identified. Or perhaps the set of three LS257 quad 2:1 multiplexers are configured as a 4:1 multiplexer for the top address bits A19:A16 -- it's probably time to get out the multimeter and find out what the jumpers are connected to!

[I'm also the owner of an unidentified / unknown RAM expansion board. Unfortunately it had a leaking Varta that managed to destroy a decent chunk of the board, so it is now a donor board: a convenient source of spare 150ns 64kbit DRAM to pillage as needed. Since it was fully populated with 384K, it should last for quite a while.]
 
kdr said:
[I'm also the owner of an unidentified / unknown RAM expansion board. Unfortunately it had a leaking Varta that managed to destroy a decent chunk of the board, so it is now a donor board: a convenient source of spare 150ns 64kbit DRAM to pillage as needed. Since it was fully populated with 384K, it should last for quite a while.]
Click to expand...

Ugh, yeah, that's where a bunch of my spare DRAM has come from as well. At least the OP's board either had the battery removed or never installed!
 
glitch said:
Ugh, yeah, that's where a bunch of my spare DRAM has come from as well. At least the OP's board either had the battery removed or never installed!
Click to expand...

Removed the battery(scared of leakeage), need to get a new CR-2N 3Volt batteri.
 
It is kind of Multi I/O card

There is a clock IC MM58167AN and that small round alu can is the X-tall for that clock.
(Big square on the left is Serial com X-Tall)
Then 8250 is a serial IC.
So that has to be configured through jumpers, Fi Com 1, Com 2 etc.

Ram you must be configure the starting address and the amount of ram on the board.

My idea is that at least the config of installed RAM is correct.
Than bear in mind the age off this card 1984 wk:50 manufactured.
So think the original main board has 64K-256k mem.
At the most 512k.

Think to start with the easy Serial port config.
Com A/B I Think with interrupt levels 3-4-7
Or first is to disable/enable clock. And I just the com setting interrupt.

There is 128k RAm on board.
So A1-5 10000 could be 1000_0000 =128k
Than S1-4 should be starting address.
1001
Maybe first S1 is parity on/off
Then 1000 think also 128 as starting address.
Could be that
That you have to figure out.
 
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