Lenovo ThinkPad 600E Technical Reference Manual for the ThinkPad 600 - Page 24

Description, Microprocessor, Cache Memory Operation, System Board - thinkpad 600 memory

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Description This section describes the microprocessor, connectors, memory subsystems, and miscellaneous system functions and ports for the ThinkPad 600 computer. Microprocessor The ThinkPad 600 uses the Intel Pentium II 233 MHz processor with MMX technology or the Intel Pentium 233 or 266 MHz processor. The processor has a 32-bit address bus and a 64-bit data bus. It is software-compatible with all previous microprocessors. The processor has an internal, split data and instruction, 32-KB write-back cache. It includes pipelined math coprocessor functions and superscalar architecture (two execution units). Cache Memory Operation In addition to the 32 KB of internal Level 1 (L1) cache memory in the microprocessor, the system board of the ThinkPad 600 computer contains an additional 512 KB of external Level 2 (L2) cache memory. The cache memory in the Intel Pentium II microprocessor and the L2 external cache memory enable the microprocessor to read instructions and data much faster than if the microprocessor had to access system memory. When an instruction is first used or data is first read or written, it is transferred to the cache memory from main memory. This enables future accesses to the instructions or data to occur much faster. The cache is disabled and empty when the microprocessor comes out of the reset state. The cache is tested and enabled during the power-on self-test (POST). The cache memory in the Intel Pentium II microprocessor is loaded from system memory in 32-byte increments, each referred to as a cache line. A cache line is aligned on a paragraph boundary. A reference to any byte contained in a cache line results in the entire line being read into the cache memory (if the data was not already in the cache). When the microprocessor gives up control of the system 2-2 System Board

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Description
This section describes the microprocessor, connectors, memory
subsystems, and miscellaneous system functions and ports for the
ThinkPad 600 computer.
Microprocessor
The ThinkPad 600 uses the Intel Pentium II
233 MHz processor
with MMX
technology or the Intel Pentium
233 or 266 MHz
processor.
The processor has a 32-bit address bus and a 64-bit data bus.
It is
software-compatible with all previous microprocessors.
The
processor has an internal, split data and instruction, 32-KB
write-back cache.
It includes pipelined math coprocessor functions
and superscalar architecture (two execution units).
Cache Memory Operation
In addition to the 32 KB of internal Level 1 (L1) cache memory in the
microprocessor, the system board of the ThinkPad 600 computer
contains an additional 512 KB of external Level 2 (L2) cache
memory.
The cache memory in the Intel Pentium II microprocessor and the L2
external cache memory enable the microprocessor to read
instructions and data much faster than if the microprocessor had to
access system memory.
When an instruction is first used or data is
first read or written, it is transferred to the cache memory from main
memory.
This enables future accesses to the instructions or data to
occur much faster.
The cache is disabled and empty when the microprocessor comes
out of the reset state.
The cache is tested and enabled during the
power-on self-test (POST).
The cache memory in the Intel Pentium II microprocessor is loaded
from system memory in 32-byte increments, each referred to as a
cache line
.
A cache line is aligned on a paragraph boundary.
A
reference to any byte contained in a cache line results in the entire
line being read into the cache memory (if the data was not already in
the cache).
When the microprocessor gives up control of the system
2-2
System Board