Compaq Portable II Maintenance And Service Manual page 33

Defective Memory Chip Isolation Map for System Boards using 64K RAMs and
256K RAMs
Memory error codes are in the format XX000B YYZZ.
XX is the memory segment of detected error.
000 is always equal to 000 (not used)
B Byte bank location (Low: B = 0, High: B = 1)