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 RAM card - what is it? View next topic
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max



Joined: 29 Mar 2008
Posts: 51
Location: czech republic

PostPosted: Fri May 07, 2010 12:16 pm Reply with quoteBack to top

Recently I obtained a RAM card. I suppose it is kind of EMS card for XT. But I am not sure. Photo is here:

http://picasaweb.google.cz/lh/photo/kMoZOvIhoNj358aPiD3e0g?feat=directlink

Does anyone know what is it? What drivers do I need to make it work?
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Puckdropper
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Joined: 02 Oct 2004
Posts: 759
Location: Not in Chicago

PostPosted: Fri May 07, 2010 6:50 pm Reply with quoteBack to top

Many of the RAM cards I've used have just needed to be plugged in to work. There's nothing extra on the card, so there's not anything to support.

The XT may not support all that RAM, so you may need a program to create a RAM drive to use the extra memory.

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386er



Joined: 27 Jan 2007
Posts: 274
Location: USA

PostPosted: Fri May 07, 2010 9:55 pm Reply with quoteBack to top

how much ram is on that card?, i belive xt's can only handle 1mb total, someone correct me if im wrong. its only got memory chips on it so it should be one that just drops in and runs. goodluck
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Anonymous Coward



Joined: 20 Nov 2004
Posts: 589
Location: Shandong, China

PostPosted: Sat May 08, 2010 10:19 pm Reply with quoteBack to top

What you have is a proprietary expansion board for a 286 or 386 class system. The dead giveaway is where is says "4M RAM Card" in the bottom right hand corner. It could not possibly be an EMS card, because there is no supporting hardware on the card at all. It's simply a coincidence that it uses what appears to be an 8-bit ISA connector.
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wdegroot



Joined: 03 Feb 2006
Posts: 488
Location: pennsylvanai

PostPosted: Mon May 10, 2010 3:08 pm Reply with quoteBack to top

to me it looks like a memory cazrd to bring an xt or pc 256 motherboard up to 649k.
there were some boards that would upgrade the 15-64 ibm pc mb from it's max of 64k to add the ram on the add-on board.
the ibm xt board usually was a 256 k board but a slight mod could allow the full 640k on the mb.
the last manufactured had 640k on the board.
but all ibm xt boards could take the non-permanent modification.
the ibm pc came 16-64 ( 4116 16k chips ONLY)
later Ibm pc boards were 64-256
a 256k xt clone mb seemed to work with 2 rows of 64k chips and 2 rows of 356k chips
BUT IT REALLY DID NOT
if the same chips were installed on a board like you show
the Full 640k would be available.

a 286-surprisingly I once saw a ast 6 pack card ( 8 bit) used for memory expansion on a ibm at-285
but the real memory expansion cards for any 286 were 16 bit cards.

so it is likely a card to fill in less than 640k up to 640. some add-on cards had sart mem ory settings for 16k mem some did not.
I do not think any clone board was less than 256m capable.
remember nothing was PNP then
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max



Joined: 29 Mar 2008
Posts: 51
Location: czech republic

PostPosted: Mon May 10, 2010 7:05 pm Reply with quoteBack to top

I think Anonymous Coward is right (thanks BTW. I was especially looking forward to see your opinion) The description on the card says 4M RAM card, so it is not for XT with 256k to fill to 640k. It is something else.
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wdegroot



Joined: 03 Feb 2006
Posts: 488
Location: pennsylvanai

PostPosted: Mon May 10, 2010 10:36 pm Reply with quoteBack to top

I have somewhere 2 rambank card 9 that is a card that provides a big ramdisk. there were "tricks"" to use tiny bits of memory unused by the video adapter between 640 & 1 m.. Some later Xt' clones came with 36 256k chips and some of that ram could be used.

my memo 576 is similar to the card shown to backfill memory up to 640k.

I think that an 8 bit card would NOT properly provide memory to increase the ram in an at from the typical 512 to 640k

somewhere I have a stack of ast 6 pack cards for xt's or [pc's . when WU downsized that tossed the ibm pc mb. they supposedly all work.
as I go thru the big pile i will mention it.,

I still have that fliptop xt clone case someone wanted.

I have a couple of intel boards that add to a at from 512 or 640 rr 1m or 4 m up to the 286 limit of 16 megs.
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ryan



Joined: 19 Apr 2006
Posts: 261
Location: WisConSin

PostPosted: Wed May 12, 2010 10:35 pm Reply with quoteBack to top

Anonymous Coward wrote:
What you have is a proprietary expansion board for a 286 or 386 class system. The dead giveaway is where is says "4M RAM Card" in the bottom right hand corner. It could not possibly be an EMS card, because there is no supporting hardware on the card at all. It's simply a coincidence that it uses what appears to be an 8-bit ISA connector.


4MB and 4Mb are different 4 mega bits is only 512kb, looking those are 18pin ram chips, 18pinners never allowed more than 512k bit density, meaning you can't install more than 1mb on that card.

Next 8bit cards only have 20 memory lines the 16bit section has the other 4, no way to locate 8bit isa memory to extended without a bios, hardware and software support (like "chips" chipsets)

And looking it appears to me to be a card that matches the old Kaypro 8 bit isa passive backplane motherboard memory card to me, I still have one similar to that in my stash somewhere. It was weird teh mobo had nothing but slots the processor was on an iSA card and the memory was all also on a isa card, only thing on the motherboard was power, the keyboard was on the cpu card.

All 640k was on one memory card because the mobo lacked any memory slots.

Cheers
Ryan
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T-R-A



Joined: 02 Oct 2004
Posts: 576
Location: Western NC

PostPosted: Thu May 13, 2010 9:40 am Reply with quoteBack to top

Quote:
It was weird teh mobo had nothing but slots the processor was on an iSA card and the memory was all also on a isa card, only thing on the motherboard was power, the keyboard was on the cpu card


What you're describing is a "backplane system". They were a lot more common in the early days than you might think. Early Zenith (ZDS) desktops were almost exclusively backplane, and Texas Instruments also experimented with the design in the "near-clones" that it first developed.
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Anonymous Coward



Joined: 20 Nov 2004
Posts: 589
Location: Shandong, China

PostPosted: Thu May 13, 2010 3:09 pm Reply with quoteBack to top

I'm quite certain that 18-pin DIPs can support 1mbit densities, because that's the type that Amiga 2000s any many 286 motherboards accept. Infact, I believe 4mbit chips exist in 18-pin format as well, but they are quite uncommon. The part number listed on the chips is "HYB511000A". If you search for the datasheet you see that it is indeed a 1mbit part.

Since it's established that the card is really 4MB and not 512kb (4mbit), we can safely assume that it is not for ISA bus, because it's definetly not an EMS card, and 8-bit ISA doesn't have enough address lines to support more than 1MB. It's proprietary hardware. If you spend enough time looking on TH99 you can probably find the matching motherboard.
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