IBM 560 Computer Monitor User Manual


 
Memory
The ThinkPad computers use the following types of memory:
Read-only memory (ROM)
Random access memory (RAM)
Real-time clock/complementary metal-oxide semiconductor RAM
(RT/CMOS RAM)
ROM Subsystem
The ROM subsystem consists of four banks of 128KB memory.
ROM is active when power is turned on and is assigned to the top of
the first and last 1MB of address space (hex 000F0000–000FFFFF
and hex FFFF0000–FFFFFFFF). After POST checks that system
memory is operating correctly, the ROM code is copied to RAM at
the same address space, and ROM is disabled.
RAM Subsystem
The RAM subsystem on the system board starts at address
hex 00000000 of the address space. The RAM subsystem for the
ThinkPad 560 is 64 bits wide.
The 8MB (ThinkPad 560) or 16MB (ThinkPad 560E) base memory is
on the system board. One 144-pin 8-byte dual inline memory
module (DIMM) connector is provided on the system board. This
connector accepts a 8MB, 16MB, 32MB, or 64MB
1
DIMM. The
memory capacity can be increased up to 40MB (ThinkPad 560) or
80MB (ThinkPad 560E) when a DIMM is used (see “System Board
Memory Connector for DIMM” on page 2-14).
The total amount of usable memory is less than the amount of
memory installed because of ROM-to-RAM remapping and power
management.
1
A 64MB DIMM is supported by ThinkPad 560E only.
ThinkPad 560/560E System Board 2-13