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Technical Reference Guide
Compaq Deskpro EN Series of Personal Computers
Desktop and Minitower Form Factors
Third Edition - September 1998
3-3
3.2.1 PROCESSOR
The system board includes a Slot 1-type interface that accommodates a Pentium II or Celeron
processor. Table 3-1 provides a comparison between the key parameters of the Pentium II and
Celeron processors.
Table 3–1.
Processor Comparison
Table 3-1.
Processor Comparsion
Pentium II
266-333
Celeron
266/300
Celeron
300A/333
Pentium II
350
Pentium II
400
Pentium II
450
CPU Freq. 266-333 MHz 300 MHz 300/333 MHz 350 MHz 400 MHz 450 MHz
L2 Cache 512 KB 0 KB 128 KB 512 KB 512 KB 512 KB
L2 Cache Freq. 133-166 MHz -- 300/333 MHz 175 MHz 200 MHz 225 MHz
Host Bus Freq. 66 MHz 66 MHz 66 MHz 100 MHz 100 MHz 100 MHz
3.2.1.1 Pentium II Processor
The Intel Pentium II processor is packaged in a Single Edge Connector (SEC) cartridge that
contains the microprocessor and a 512-KB ECC secondary (L2) cache. The processor’s
architecture (Figure 3-2) includes a dual-ALU MMX-supporting CPU, branch prediction logic,
dual-pipeline floating point unit (FPU) coprocessor, and a 32-KB L1 cache that is split into two
16-KB 4-way, set-associative caches for handling code and data separately. These functions
operate at core processing speed (Figure 3-2), which ranges from 266 to 400 megahertz
depending on version.
Figure 3–2.
Pentium II Processor Internal Architecture
The Pentium II processor includes 512 kilobytes of SRAM for the write-through L2 cache.
Accesses with the L2 cache occur at 50% of the core processing speed. The front side bus (FSB,
also referred to as the Host bus) interface of the 266-, 300-, and 333-MHz processors operates at
66-MHz. The FSB interface of the 350- and 400-MHz processors operates at 100 MHz. The
Pentium II processor is software-compatible with earlier generation x86 microprocessors.
NOTE:
Later versions of the Pentium II processor require updated BIOS firmware.
Refer to section 3.2.2 for upgrading information.
Pentium II Processor
CPU
Branch
Prediction
FPU 32-KB
L1
Cache
512-KB
L2
Cache
FSB
I/F
Core processin
g
speed ½ Core processin
g
speed
Host bus speed