[comp.sys.ibm.pc] AT-memory split problem

ccenol@rivm.UUCP (Arnold Reinders) (08/22/88)

I have a problem with my 10 Mhz AT-clone. It has 1 megabyte of memory
on the motherboard, but the machine is only configurable as:

 1. 512 Kb main memory and 512 Kb extended memory
 2. 640 Kb main memory and 0!! Kb extended memory

My dealer says it's a bug on the motherboard, but I can' vouch for his
reliability.
Does anyone know how I can configure the machine with 640 Kb main memory
and 384 Kb extended memory? Any help would be appreciated. Thanks in advance.

Arnold Reinders

richard@neabbs.UUCP (RICHARD RONTELTAP) (08/23/88)

Bad news, I have such a machine too. (maybe even the same)
 
I've also tried various tricks, but couldn't use the remaining 384K
with 640K main memory active.
 
I think it is more a design descision of the manufacturer in stead of
a bug.
 
Richard

phil@amdcad.AMD.COM (Phil Ngai) (08/24/88)

In article <994@rivm05.UUCP> ccenol@rivm.UUCP (Arnold Reinders) writes:
>Does anyone know how I can configure the machine with 640 Kb main memory
>and 384 Kb extended memory? Any help would be appreciated. Thanks in advance.

You are probably SOL. If your motherboard uses CHIPS devices which are
not of the NEAT flavor, you are definitely SOL. Look for the 82C202
chip.  I don't know about Zymos or whoever. What I do is put 64K chips
in the motherboard's second bank, as they are real cheap.  Then if I
had the extra 256K chips, I'd buy a expanded memory board and use it
as RAM cache. 
-- 
Why do Big-Endians number their bytes backwards from their bits?

I speak for myself, not the company.
Phil Ngai, {ucbvax,decwrl,allegra}!amdcad!phil or phil@amd.com

suhans@let.vu.nl (suhans) (08/24/88)

In article <994@rivm05.UUCP>, ccenol@rivm.UUCP (Arnold Reinders) writes:
> I have a problem with my 10 Mhz AT-clone. It has 1 megabyte of memory
> on the motherboard, but the machine is only configurable as:
> 
>  1. 512 Kb main memory and 512 Kb extended memory
>  2. 640 Kb main memory and 0!! Kb extended memory
> 
> My dealer says it's a bug on the motherboard, but I can' vouch for his
> reliability.
> Does anyone know how I can configure the machine with 640 Kb main memory
> and 384 Kb extended memory? Any help would be appreciated. Thanks in advance.


The problem of 512 kb + 512 kb ext or 640 kb with 0 kb ext is a
fault in the main board.
It's not a bios problem but a hardware problem.
I've the same problem and it can't be solved by my dealer.
The only solution is to put 512 kb + 128 kb on the main board and
the other 512 kb on a extended memory board +/- F 200,- with 0 kb.
I have done that.

-- 
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Name:		Hans Varkevisser (system administrator) 
                hans@let.vu.nl  or let.vu.nl!hans