AMD 1.8 to P4 2.8 Dos Memory problems

Not enough memory to run Dos!?

[Brett_Tabke]

I switched mb's from a 1.8 anthlon to a p4 2.8 with 800mhz fsb (with 1 gig ddr). win98

The system works, but a weird problem developed in DOS mode under windows. It says it doesn't have enough memory to run a Dos box.

I've messed with everything I can think of in a config sys and nothing seems to help it. (changes memory managers...etc)

It WILL boot to a Dos prompt, but it will NOT load dos into an upper memory block (barfs on dos=umb).

This is all under 98.

any thoughts? (everything else on the machine - including windows 98 - runs great). However, XP will NOT install because it runs out of memory too.

hmm - any thoughts or clues?

[DaveAtIFG]

If DOS can't access extended memory, it ain't there! :)

Probably something in the BIOS is blocking you. Knowing which MB/BIOS may help.

[Macro]

Brett, you can't run 1024 MB of RAM in Win 98 unless you tweak the MaxFileCache and MinFileCache settings of system.ini

[bcolflesh]

Macro is correct - info here:

support.microsoft.com/default.aspx?scid=kb%3ben-us%3bQ253912

[Brett_Tabke]

hmmm. The system *had* 768 in it before I switched mbs.

[Macro]

Simple test - take out some RAM and see if it works ok

[bcolflesh]

You can add as much memory as you like - Win 98 can only address 512megs of it though - as you move higher you get the memory errors you are experiencing.

[DaveAtIFG]

Download MemTest86 [memtest86.com] and check the basics. It has it's own bootstrap loader and memory detection routines, no DOS. Check the basics.

You're most likely using different memory on this MB and it wouldn't hurt to verify that it works as it should.

[Macro]

I think DAve is onto something there.

[Brett_Tabke]

Thanks for the ideas guys - I'll let you know. working on it...

[Brett_Tabke]

Well, when it boots to windows - it knows it has 1g to work with and by my tests - it *is* using all of it. This has something to do with dos mode only. That's why I keep coming back to a memory manager issue. I will try the vcache tweaks.

[Brett_Tabke]

This place always come through in the clutch!

I pulled out a 512m dimm and she booted and I clicked right to dos - no problemo.

Thanks Guys!

[txbakers]

This place always come through in the clutch!

Yes, we try to be helpful. You're welcome to post again anytime you need help. 8)

I had heard that new 64 bit CPUs will break the 4GB RAM barrier as well.

[Macro]

I had heard that new 64 bit CPUs will break the 4GB RAM barrier as well

I've been playing around with those babies, the FX-51s and Athlon 64s, including the new 3400s. The thing I'm surprised about is that they work. I'v tried them with different AGP cards, different makes of ECC RAM (where ECC was required), different hard disks and soundcards etc. I don't know why I expected them to fall about all over the place. Maybe I've been in the business too long ;-)

[jim_w]

Maybe it has something to do with addressing and the CPU cache. Wonder what would happen if you disabled the all the CPU caches and put the memory back in?

[Macro]

I pulled out a 512m dimm and she booted and I clicked right to dos - no problemo

What happens if you swap DIMMS?