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A Pentium compatible processor (or Pentium clone) is a 32-bit processor computer chip which supports the instructions in the IA-32 instruction set that were implemented by the Intel P5 Pentium processor family (also known as Classic Pentium, or original Pentium). The IA-32 instruction set first appeared in the 80386 processor; the 80486 added a few instructions to IA-32, and the P5 Pentium family added a few more instructions beyond that.

Pentium compatible processors are sometimes referred to as 586-architecture processors.^{[citation needed]} Later processors are also considered to be Pentium compatible, because they still support the instructions supported by the P5 Pentium family.

This class of processors is typically used in IBM PC compatible computers.

List[link]

Here are some processors that implement all of the instructions that the P5 Pentium processor family implemented:

• AMD K5
• AMD K6
• AMD Athlon
• AMD Duron
• AMD Opteron
• AMD Athlon 64

• Intel Pentium III
• Intel Pentium 4
• Intel Pentium D
• Intel Celeron
• Intel Xeon
• Intel Pentium M
• Intel Core
• Intel Core 2
• VIA C3
• VIA C7
• VIA Nano

Software Compatibility[link]

Any software that uses only instructions supported by the P5 Pentium processor family, and that can run on that processor is considered to be Pentium compatible.

Software that uses instructions added to IA-32 after the P5 Pentium was released, and that therefore will not run on a vanilla P5 Pentium, is considered not to be Pentium compatible.

64-bit Processors[link]

Recently, 64-bit processors, such as the AMD Athlon 64, are becoming more popular. These processors allow much larger application address spaces in computers using them. The 64-bit AMD64 instruction set is not supported by the P5 Pentium processor family, so 64-bit software will not work on Pentium compatible systems or post-Pentium compatible processors that only support the 32-bit IA-32 instruction set.