IBM 6151 Maintenance And Service Manual page 82

lEx
RT PC 8MB Fast Memory Expansion Option
Additional Tests: None
Removal Procedure: See Processor, Floating-Point, or System
Memory Removal in Section 4.
Repair Checkout: Run the System Checkout.
20x
RT PC AT Coprocessor Option
Additional Tests: None
Removal Procedure: See "Removal and Replacement
Procedures" on page 9-023-1.
Repair Checkout: Run the System Checkout.
2lx
IBM AT 512 KB Memory Expansion Option
Do not return to the Start of Call
PIC,
go to "Memory
Expansion Option
PIC
2100" on page 3-2100-1.
3-0020-4 Service Manual