IBM 5150 PC w/ 2nd rev MB(256KB) - Lo-tech 1MB ISA 8 bit ram expansion rev 1 card not detected

[netmosis]

Hoping someone might have some advice on this issue. I am running the lo-tech rev 1 card on an IBM 5150 w/ 256KB of ram on the main board. Booting into DOS 3.30 from floppy(tried both MS DOS and PC DOS), using CHKDSK and seeing 256KB or total memory. Not seeing additional 384K from the lo-tech card. On the card I have sw1-1 thru sw1-4 off, sw1-5 thru sw2-2 on(to enable 256K - 640K), sw2-3 thru sw2-8 off. Also tried all the ISA slots. The slots do work fine for an EGA card, a monochrome card, and the dual floppy controller. I'm starting to think its a problem with the lo-tech card but I'm a newbie to the 5150.

 

[Eudimorphodon]

Did you set the motherboard DIP switches to the full combined amount (motherboard plus card) amount of RAM? See here:

minuszerodegrees.net

I don’t think the 5150’s BIOS probes for memory, you have specifically set it.

 

[modem7]

I don’t think the 5150’s BIOS probes for memory, you have specifically set it.

Confirmed.
Motherboard switch block SW2 will need to be altered.

... but I'm a newbie to the 5150.

Lots of IBM 5150 information at minuszerodegrees.net
With you being a 'newbie', the 'Basics' link in the IBM 5150 section is a must to read.

 

[netmosis]

Confirmed.
Motherboard switch block SW2 will need to be altered.


Lots of IBM 5150 information at minuszerodegrees.net
With you being a 'newbie', the 'Basics' link in the IBM 5150 section is a must to read.

Thanks, that was it! Had to change SW2 to be set to 640KB, CHKDSK now shows 640K.

 

[maelstrm]

You mean MEM.EXE?

 

[netmosis]

You mean MEM.EXE?

No, just CHKDSK, MEM was introduced in DOS 4.0, not found on 3.30 - I'm struggling with an XTIDE Deluxe rev 1 ISA card as well, currently limited to my physical floppies of DOS 3.30 until I get that to work. I may post about that soon but will start a new thread if I do.

 

[Eudimorphodon]

You mean MEM.EXE?

MEM.EXE didn’t exist on DOS versions prior to 4.0. So on older versions CHKDSK, for some reason, when run without arguments will tell you how much memory DOS sees.

 

[maelstrm]

MEM.EXE didn’t exist on DOS versions prior to 4.0. So on older versions CHKDSK, for some reason, when run without arguments will tell you how much memory DOS sees.

Wow, I didn't know that. Thank you!