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IBM Extended Memory Card Switchblock Settings?

S

Super-Slasher

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Ontario, Canada... the frosty north.
Ugh, now I got a new problem...

After successfully getting a 1.44MB drive to work on my AT, I was attempting to install Windows 3.1 which required extended memory. While reaching for my extended memory card, I was horrified to discover while the night before, one of my friends needlessly reset all the switches on the switchblock to OFF... and I don't remember what they were all set to. My system will not post with the card installed.

Can anyone help me with these switch settings? The card is an IBM "DET 55X3544", has serial and parallel ports (which strangely enough never worked), and 12 30-pin SIMM slots (6 low byte, 6 high byte). The switch block has 8 switches.
 
The switchblock is probably the starting memory address for the card.

It depends on what is on the card in total as to what the switches might represent. If I were to guess (and this is only a guess) there would be 4 switches dedicated to determining which 64K block the card addressed at. The rest would probably turn on or off some of the other functionality (such as ports, etc.)

Of course, that's only a guess. You really need someone with the manual for this particliar card (or a very close relative of it) to tell you exactly what the switches do.

Failing that, you might be able to "reverse engineer" the card if you can see all the traces from the ISA bus to the switchblock. Unfortunately, it's probably a multi-layer board. . .

Good luck!

Erik
 
SuperSlasher:

The worst case is you might have to work it out by trial and error. Remember there are only 256 different combinations of 8 switches. Start from 00000000 and work your way to 11111111. This shouldn't take much more than a day or so.

--T
 
Who said 13 was not a lucky number? Glad you got it so easily. BTW, did you manage to enable the serial and parallel ports? Prolly a couple of those switches will do that fr ya...

--T

(WhooHoo! I finally managed to break 100 posts on this board!)
 
Terry Yager said:
Who said 13 was not a lucky number? Glad you got it so easily. BTW, did you manage to enable the serial and parallel ports? Prolly a couple of those switches will do that fr ya...

--T

(WhooHoo! I finally managed to break 100 posts on this board!)
Click to expand...

No, net yet, the ports on the card still seem to be inactive. I'll try remedying that later on - got a seperate serial/parallel board I can use in the meantime.
 
Dredging up an old thread ...

I have one of these cards. I think the proper part number is 55X3543. It is a 16 bit memory expansion card that has room for 12 30 pin SIMMs, a serial port and a parallel port.

My IBM documentation doesn't have anything on this card. I suspect it was designed for the ISA PS/2 series, but a happy side effect is that it works in the PC AT as well. I don't have any PS/2 documentation that helps though.

Do any of you IBM documentation collectors have PS/2 specific docs? If so, can you take a look for a 16 bit ISA memory card?


Thanks,
Mike
 
Ah, thank you - that looks like a perfect match, and I don't know how I missed it the first time.

This card is a little more advanced that I thought it would be - apparently it can use 1MB SIMMs, where I thought it would use just 256KB SIMMs. Now it is time to start looking for SIMMs to populate it with. :)
 
I also have one of those same cards ....mine was in an IBM AT
that I bought used a long time ago.

This card has four very unusual SIMMS. The chips are the really old
style IBM metal cans :)

Here's a couple of pictures:
 

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mikey99 said:
I also have one of those same cards ....mine was in an IBM AT
that I bought used a long time ago.

This card has four very unusual SIMMS. The chips are the really old
style IBM metal cans :)

Here's a couple of pictures:
Click to expand...

I have even weirder looking SIMMs in my PS/2 Model 30 286. I'll get a pic at some point, since you brought up weird memory maybe I can get an answer about what exactly mine is at the same time.
 
Last edited:
I think its just an older technology memory ..... I remember seeing these
metal can type of memory chips in mainframes back in the 1970's.

BTW, thanks for posting those pictures, maybe we need a thread where everyone can
post their most unusual computer part/card :)

kishy said:
Alright...so my PS/2 30-286 came to me with 2 of these weird things installed, and two more normal looking ones. It totals to 1024K so I imagine they're 256K each.

Without removing too much from the thread, what exactly is the technology behind these so I can do my own further investigating? I wouldn't know what to even call it.
Click to expand...
 
It´s important to note that these IBM 30-pin SIMMs are not quite the same pinout as later 30-pin SIMMs. 256Kb versions (including the ´silver´cap´ or ´silver sugarcube´ style) are common on the Models 25, 30, 50, 60, and Spock SCSI caching controller. 1Mb models are rare, but there is a documented mod that changes a few pins on some standard 1Mb SIMMs to make them work in the mentioned IBM systems (this card and the Spock adapter included).
 
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