IBM XT 640K mod: when it goes wrong

[brtb]

So just a little note for anybody doing the 640K mod on the 64-256K motherboards: if your POST is stuck at "064 KB OK" once you're done, and you can't figure out why...

The 256K chips go in banks 0+1, not 2+3.

:roll: :lol:

 

[fs5500]

Did you read this sentence?

http://www.minuszerodegrees.net/5160/motherboard/5160_motherboard_revisions.htm

http://minuszerodegrees.net/5160/motherboard/5160_upgrading_256k_motherboard_to_640k.pdf

 

[brtb]

Did you read this sentence?

http://www.minuszerodegrees.net/5160/motherboard/5160_motherboard_revisions.htm

http://minuszerodegrees.net/5160/motherboard/5160_upgrading_256k_motherboard_to_640k.pdf

Sure did. But it was past midnight when I swapped all the chips the first time and got it backwards anyway. Then wasted more time searching for what makes the memory test get stuck at 64K... thought I'd help save others from my stupid late-night mistakes