IBM 5170 - Some examples of [6181024][6181025][6181026][6181027] BIOS ROM sets
These are 27128 EPROM's, found on very early type 1 motherboards.
Accordingly, shunt block U131 on the motherboard (see here) needs to be set to the '27128' position.
Photo source:
fs5500 at the Vintage Computer Forums
Photo source:
phonophan at the Vintage Computer Forums