Lenovo ThinkPad 600E Technical Reference Manual for the ThinkPad 600 - Page 37

Memory, ROM Subsystem, RT/CMOS RAM - thinkpad 600 ram

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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 128-KB memory. ROM is active when power is turned on and is assigned to the top of the first and last 1 MB 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 600 computer is 64 bits wide. The 32-MB base memory is on the system board. Two 144-pin 8-byte dual inline memory module (DIMM) connectors are provided on the system board. Both connectors accept an 8-MB, a 16-MB, a 32-MB, or a 64-MB DIMM. The memory capacity can be increased up to 160 MB. The total amount of usable memory is less than the amount of memory installed because of ROM-to-RAM remapping and power management. System Board 2-15

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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 128-KB memory.
ROM is active when power is turned on and is assigned to the top of
the first and last 1 MB 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 600 computer is 64 bits wide.
The 32-MB base memory is on the system board.
Two 144-pin
8-byte dual inline memory module (DIMM) connectors are provided
on the system board.
Both connectors accept an 8-MB, a 16-MB, a
32-MB, or a 64-MB DIMM.
The memory capacity can be increased
up to 160 MB.
The total amount of usable memory is less than the amount of
memory installed because of ROM-to-RAM remapping and power
management.
System Board
2-15