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Intel Pentium Pro 256 KB - KB80521EX 256K

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This part is an engineering sample.

Intel KB80521EX 256K specifications

General information
TypeCPU / Microprocessor
Market segmentServer
FamilyIntel Pentium Pro
CPU part numberKB80521EX 256K is an OEM/tray microprocessor
Package387-pin Modified Staggered Ceramic Pin Grid Array with gold plated heat spreader
2.66" x 2.46" (6.76 cm x 6.25 cm)
SocketSocket 8
S-spec numbers
  ES/QS processors
Part number Q0720 Q0721 Q0754 Q0755 Q0765 Q0766
KB80521EX 256K++++++
Architecture / Microarchitecture
Manufacturing process0.6 and 0.35 micron
5.5 million transistors
Data width32 bit
Data bus width64 bit
Floating Point UnitIntegrated
Level 1 cache size  ? 8 KB four-way set associative code
8 KB two-way set associative data
Level 2 cache size  ? 256 KB
MultiprocessingUp to 4 processors
Low power features
  • Stop Grant mode  ? 
  • Auto HALT mode  ? 

Detailed side-by-side comparison

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CPU ID information for the KB80521EX 256K

Our CPUID database contains 2 records for this microprocessor. See all submitted records.

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NOTE: The CPU ID information below was taken from one CPU and may include features that are not present in all different steppings of the Intel Pentium Pro KB80521EX 256K CPU.

CPU Family:Pentium Pro
Processor Number:
Frequency:100 MHz
Part number:
KB80521EX 256K
S-Spec Number:Q0720
Submitted by:Greg G.
General information
Processor type:Original OEM Processor
CPUID signature:610
Family: 6 (06h)
Model: 1 (01h)
Stepping: 0 (00h)
TLB/Cache details:Data TLB: 4-KB Pages, 4-way set associative, 64 entries
Data TLB: 4-MB Pages, 4-way set associative, 8 entries
Instruction TLB: 4-KB Pages, 4-way set associative, 32 entries
Instruction TLB: 4-MB Pages, fully associative, 2 entries

Cache: L1 data L1 instruction L2
Size: 8 KB 8 KB 256 KB
Associativity: 2-way set
4-way set
4-way set
Line size: 32 bytes 32 bytes 32 bytes
Instruction set extensionsAdditional instructions
Major featuresOther features
On-chip Floating Point Unit Advanced programmable interrupt controller
  Debugging extensions
  Machine check architecture
  Machine check exception
  Memory-type range registers
  Model-specific registers
  Page global extension
  Page-size extensions (4MB pages)
  Physical address extensions
  Time stamp counter
  Virtual 8086-mode enhancements

CPUs, related to Intel Pentium Pro KB80521EX 256K

Model Frequency L2
TDP Features  
Intel Pentium Pro family, Socket 8
   Pentium Pro KB80521EX 256K 256 KB4  
   Pentium Pro 133 MHz (KB80521EX-133 256K)133 MHz256 KB4 >
   Pentium Pro 150 MHz (KB80521EX150 256K)150 MHz256 KB429.2W>
   Pentium Pro 166 MHz (KB80521EX166 512K)166 MHz512 KB435W>
   Pentium Pro 180 MHz (KB80521EX180 256K)180 MHz256 KB431.7W>
   Pentium Pro 200 MHz (KB80521EX200 256K)200 MHz256 KB435W>
   Pentium Pro 200 MHz (KB80521EX200 512K)200 MHz512 KB437.9W>
   Pentium Pro 200 MHz (GJ80521EX200 1M)200 MHz1 MB447W>
Other families, P6 micro-architecture, Socket 8
   Pentium II Overdrive 333 MHz (PODP66X333)333 MHz512 KB  MMX>
 • Within each category, the CPUs are sorted from slower (at the top) to faster (at the bottom)
 • Background color of specs and features indicate whether they are better or worse than similar spec/feature of the Pentium Pro KB80521EX 256K
 • Engineering samples are marked with this color
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 • Features abbreviations:
MMX - MMX instructions

Pictures (1)

Engineering sample

256 KB L2 cache
387-pin modified SPGA
Gold plated heat spreader
Image reduced 2x times

Engineering sample
Intel Pentium Pro 256 KB - KB80521EX 256K
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