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IBM 5150  -  Motherboard Revisions


There were 2 revisions of the motherboard.

IBM differentiated them by the amount of RAM that it was possible to fit on the motherboard:
   • 16KB-64KB
   • 64KB-256KB

Both were not released simultaneously. The 16KB-64KB motherboard was supplied in early model 5150s, and the 64KB-256KB motherboard was supplied in later model 5150s.


Example marking Motherboard RAM     Comments
aaa  4 banks of 16 KB  • Detail on the RAM for this motherboard is here.
 
 • Supplied with either the 04/24/81 or 10/19/81 revision of BIOS.
 • It was common for owners to upgrade the BIOS to the 10/27/82 revision via a BIOS upgrade kit.  See note 1.
aaa  4 banks of 64 KB  • Detail on the RAM for this motherboard is here.
 
 • Supplied with the 10/27/82 revision of BIOS.  See note 1.




Note 1 Due to bugs, the 10/27/82 revision of BIOS requires that all 4 banks of motherboard RAM be populated.