28. 80486 CPU

• Year 1989.

• The 80486 processor is an enhanced version of the 80386 with

  • instruction pipelining allows parallel execution capability to instruction decode and execution units.

  • executes many instructions 2-3 times faster.

  • achieves scalar execution of 1 instruction per clock cycle.

• The chip incorporates

  • math coprocessor for performing floating-point arithmetic

  • 8 Kilobyte memory cache.

  (The math coprocessor was disabled on a variation of the chip called the 80486SX.)

• New instructions.

• Fully compatible with 80386 software.

• Later versions introduced energy savings for laptops.

• See also: Intel 486 Manuals