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IBM 5150 motherboard  -  ROM's  -  Adapter choice


If you want to use a 27xxx type EPROM on an IBM 5150 motherboard, then you need to use a suitable adapter between the EPROM and the motherboard.


Option #1:  Purchase

An adapter that will work with 2764, 27128, 27256 and 27512 EPROM's (or 27C64/27C128/27C256/27C512) is described at here.
That adapter is described as "2364 Adapter".  From a reading perspective, the 2364 ROM is pin compatible with the BIOS ROM used on the IBM 5150 motherboard.  I have one of these adapters, and it works.
Note that the seller offers either the PCB alone, or a complete unit.

That particular adapter ties pins 1, 26 and 27 of its 27xxx EPROM socket to Vcc (via a pull-up resistor).  Therefore, when this adapter (as supplied) is used on the IBM 5150 motherboard, the 5150 motherboard will only see/use the last 8 KB block within 27128/27256/27512 EPROM's.


Option #2:  Homemade

An adapter that will work with 2764, 27128, 27256, and 27512 EPROM's (or 27C64/27C128/27C256/27C512), is described at here.