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getting a RAM expansion card..

M

Mike Chambers

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Sep 2, 2006
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browsing around ebay, i was looking at 8-bit ISA memory expansion and came across this.

http://cgi.ebay.com/Panasonic-Matsu...emQQptZLH_DefaultDomain_0?hash=item5627caf931

caught my eye because i'm only a 30 minute drive from the seller, and he says if i want it i can just get it in person. (im guessing the 386 KB is a typo and he meant 384)

would this work in my BMI XT clone? the mobo is loaded with 640 KB. i know an 8088 can address 1 MB of real-mode RAM, but how exactly does the system know if i've upgraded it? are there switches to tell it there is 1 MB? (iirc, the switches allow you to select up to 640 KB)

i've never had to chance to get my hands on a RAM expansion card before, so i'm a bit uninformed on the subject. my goal here is to have 1 MB so that i can actually do something useful with MINIX 2 on the system. with 640 KB, you can't do much. i can log in remotely via telnet and run vi. anything else and it runs out of memory.

with 1 MB, i'll be able to run an httpd, ftpd, and many other fun little toys.
 
The 8088 can access 1MB of memory, but part of that is reserved for the BIOS, expansion ROMs, video RAM, etc. 640KB is the most RAM you can have.

The 384K RAM card is probably meant for expanding a 256K machine to the full 640k.
 
I can almost guarantee that that card is for expanding the Sr. Partner (which I have one of). Wish I was close to there too. You can tell because it's Panasonic, and also because it has no bracket - there are two slots in a Sr. Partner, one of which is accessible in the back, and the other of which is not, and is dedicated to memory expansions like this one. ;)

As well, the Sr. Partner comes with 256K, so 256+384=640K.

If it doesn't work in your machine I'd consider buying it from you for my Sr. Partner.
 
I think you would be better off with an AST Rampage:

http://cgi.ebay.com/AST-Computer-20...emQQptZLH_DefaultDomain_0?hash=item3ef704e440

It holds up to 2mb of EMS, but some of that can also be used to backfill conventional memory. If you use it with a program like QRAM then you can also load some drivers into the area between 640k and 1mb. The only downside is the card is currently unpopulated, but it takes the standard 256kbit DRAMs.
 
Anonymous Coward said:
I think you would be better off with an AST Rampage:

http://cgi.ebay.com/AST-Computer-20...emQQptZLH_DefaultDomain_0?hash=item3ef704e440

It holds up to 2mb of EMS, but some of that can also be used to backfill conventional memory. If you use it with a program like QRAM then you can also load some drivers into the area between 640k and 1mb. The only downside is the card is currently unpopulated, but it takes the standard 256kbit DRAMs.
Click to expand...

EMS would work perfectly. minix supports it, thanks for the link. i might get that AST card. i have a dead 286 motherboard that i accidentally fried the BIOS ROM chips on that i could pull the 256kbit chips from. it has 1 MB total.
 
Raven said:
I can almost guarantee that that card is for expanding the Sr. Partner (which I have one of). Wish I was close to there too. You can tell because it's Panasonic, and also because it has no bracket - there are two slots in a Sr. Partner, one of which is accessible in the back, and the other of which is not, and is dedicated to memory expansions like this one. ;)

As well, the Sr. Partner comes with 256K, so 256+384=640K.

If it doesn't work in your machine I'd consider buying it from you for my Sr. Partner.
Click to expand...

actually, now that i understand it a little better i doubt it would work for me. feel free to buy it, he's not charging shipping on it.
 
well, either way i just came up with a little bit of a trick to let minix use 704 KB of RAM instead of the 640 KB installed in the system. i configured the kernel to add A0000 thru AFFFF to it's memory pool, which is the 64 KB of video memory on the VGA card that never gets used in minix since its only text mode.

awesome. :)
 
Anonymous Coward said:
I think you would be better off with an AST Rampage:

http://cgi.ebay.com/AST-Computer-20...emQQptZLH_DefaultDomain_0?hash=item3ef704e440

It holds up to 2mb of EMS, but some of that can also be used to backfill conventional memory. If you use it with a program like QRAM then you can also load some drivers into the area between 640k and 1mb. The only downside is the card is currently unpopulated, but it takes the standard 256kbit DRAMs.
Click to expand...

I bought this card and could never find documentation for it, always the rampage/2 not this card.
 
you know... the video card in my XT clone is a diamond speedstar (thanks trixter) with 1 MB of RAM. i know it's paged memory with a 64 KB window. isn't that the same way EMS works?

there's gotta be some way to trick the system (or rather, the minix kernel) into using the full 1 MB as if it were on an EMS expansion card. (excluding the 4000 bytes between B8000 and BC7A00 that i'm using for the 80x25 text mode)

i really should look into that. does anybody have details on how software handles EMS paging? VGA paging is pretty simple. all you do is feed it high and low start address values into two I/O registers. not sure about EMS though.
 
Last edited:
LIM EMS is less a hardware device than a software convention. In fact, it's perfectly possible to implement it using a LIMulator, such as AboveDisk and page off of hard disk.

Hardware decisions were left up to the individual vendors, which is why one vendor's driver doesn't work with another vendor's board. To make a conventional RAM board work as an EMS board would require some additional hardware to map only a selected "window" into the PC's address space.

LIM 4.1 Specification
 
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