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Intel L1A4729 Memory Board for IBM 5170

robbo007

robbo007

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Jan 7, 2012
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Iberian Peninsula
Hi guys,
I have two memory cards in my IBM 5170. One which has 128kb and another which is the Intel L1A4729 Memory Board that has 2048MB.

The intel card has 18 IC's marked: USA 87268 / 1259-12 and 36 IC's marked: KM41 256-15 / 723 Korea.

Questions:
Has anyone seen a manual for this card? To see the memory configurations, max memory etc?
I want to populate the 2 remaining banks of 9 ICs per bank. I've found on eBay some references close "KM41256 6372 Korea" Would those be compatible?
Are the IC's 256K ?

Here a photo of my card: https://ibb.co/gmk2146
 
The KM41256-15 are 256kb single bit DRAMs with an access time of 150ns. You would just need similar 256x1 DRAMs - 150ns or faster. KM is the letter code used by Samsung - that part is not important.

The ones you found on eBay may be fine, but check the speed grade. -15, -12, -10 or -80 would all work.

Can't help with the manual...
 
Picture is garbage but it looks like an Above Board. Check minuszerodegrees for the manual and configuration software
 
maxtherabbit said:
Picture is garbage but it looks like an Above Board. Check minuszerodegrees for the manual and configuration software
Click to expand...

Agreed. I took a quick picture before I left on holidays. I'm 15,000km away from my stuff at present so can't upload a better on but its definitely not an above board. It's the Intel L1A4729 memory board. Looks very different to pictures form the Above Board, I did find this image online. After looking on eBay those ic's are pretty expensive. People are charging over $5 each IC. grrrr I think I need about 18.
 

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mcs_5 said:
The KM41256-15 are 256kb single bit DRAMs with an access time of 150ns. You would just need similar 256x1 DRAMs - 150ns or faster. KM is the letter code used by Samsung - that part is not important.

The ones you found on eBay may be fine, but check the speed grade. -15, -12, -10 or -80 would all work.

Can't help with the manual...
Click to expand...

So a 80ns is fine? Are the capable of running at 150ns if the other IC's are at 150ns?
 
Agreed that the part of the board you have photographed looks like an Aboveboard 286 (got one myself), right down to component placement.

You can always substitute faster DRAM for slower ones, as long as mixtures of fast and slow operate at the slow speed. At some point, some of the 256Kb DRAM vendors just quit putting speed suffixes on their labeling--everything coming off the lines was the 80 nsec. speed.

$5 each for 41256 DRAMs sounds outrageous. You shouldn't have to pay more than about $2 each (JDR prices for NOS 80nsec).

If your board lacks the large PLCC and has DIP switches instead, you probably have an AboveBoard AT, not the 286.
 
Last edited:
robbo007 said:
So a 80ns is fine? Are the capable of running at 150ns if the other IC's are at 150ns?
Click to expand...

Yes. A faster access time just means that the memory chips will be ready before the board needs it. It will not speed up anything, but also not cause problems.

I need 18 of these ICs also. I found them at about one USD each - don't know how much the shipping will cost. I could easily order some extra. Shipment to Spain as a letter shouldn't be expensive :)
 
mcs_5 said:
I found them at about one USD each - don't know how much the shipping will cost. I could easily order some extra. Shipment to Spain as a letter shouldn't be expensive :)
Click to expand...
Actually, a letter with chips inside will be charged at the package rate as will any letter that is rigid, non rectangular, or not uniformly thick.
 
Stone said:
Actually, a letter with chips inside will be charged at the package rate as will any letter that is rigid, non rectangular, or not uniformly thick.
Click to expand...

Not in Denmark. A letter is anything up to 2kg and 90cm total (width + length + height). So you can ship ICs properly packaged in a solid box, and it's still a letter.
 
robbo007 said:
Agreed. I took a quick picture before I left on holidays. I'm 15,000km away from my stuff at present so can't upload a better on but its definitely not an above board. It's the Intel L1A4729 memory board. Looks very different to pictures form the Above Board, I did find this image online. After looking on eBay those ic's are pretty expensive. People are charging over $5 each IC. grrrr I think I need about 18.
Click to expand...

There are many different versions of Above Board and they don't all look the same. Most (all?) of them aren't silkscreened "Above Board" either.
 
1565016605_533_s-l1600-795x447.jpg

At least the photos I see when googled look like an Intel Above board with the serial and parallel ports not populated on the PCB.

9iKVJBJl.jpg

q1p9n5bl.jpg


my aboveboard has the Daughter-board and is fitted with 3.5mb of memory. configured completely with dip switches.
 
mcs_5 said:
Yes. A faster access time just means that the memory chips will be ready before the board needs it. It will not speed up anything, but also not cause problems.

I need 18 of these ICs also. I found them at about one USD each - don't know how much the shipping will cost. I could easily order some extra. Shipment to Spain as a letter shouldn't be expensive :)
Click to expand...

That sounds like a plan. Let me know the details. :)
 
After looking a little more I think my board is an Above Board Plus/Above Board 286. This document seems to match layout of my RAM banks and stuff.

https://stason.org/TULARC/pc/memory-cards/INTEL-CORPORATION-Memory-card-ABOVE-BOARD-PLUS-ABO.html

Anyone know what RAM IC's are in the BANK 0? They must be more than 256K as the entire ram on my board comes out at 2048 and the docs at Stason.org seem to show a total of 2048MB Ram would require all 4 banks occupied with 256k IC's.

Here's my pic:

https://ibb.co/gmk2146
 
They're all 256Kx1 ICs (e.g. 41256)

Each row consists of 8 x 256Kx1 or 256KB
4 rows of 256KB = 1024KB
8 rows are 2048KB.

I'm sticking by my identification of an AboveBoard 286. Note the location of the capacitor C38 near the edge connector. AFAIK, only the AB 286 is so configured. If your board has the unpopulated areas near the bracket filled, you have an AB 286 Plus. (The "Plus" simply means that you have a comm port and a few other extras).
 
Chuck(G) said:
They're all 256Kx1 ICs (e.g. 41256)

Each row consists of 8 x 256Kx1 or 256KB
4 rows of 256KB = 1024KB
8 rows are 2048KB.

I'm sticking by my identification of an AboveBoard 286. Note the location of the capacitor C38 near the edge connector. AFAIK, only the AB 286 is so configured. If your board has the unpopulated areas near the bracket filled, you have an AB 286 Plus. (The "Plus" simply means that you have a comm port and a few other extras).
Click to expand...

Thanks @Chuck for confirming this. Mine does not have any com ports so its just the AB 286 then. I just realised the RAM test counts 2048 but this includes the 640k on the motherboard which I forgot about :) So makes sense the 258kb IC's.

I see on http://www.minuszerodegrees.net there is a manual and some utilities for the Aboveboard PS/AT. Guess it's valid?

Cheers,
 
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