Differences between the 386 and 486

Differences between the 386 and 486

* An 8 KB on-chip SRAM cache stores the most commonly used instructions and data (16 KB and/or write-back on some later models). The 386 had no such internal cache but supported a slower off-chip cache.
* Tightly coupled pipelining allows the 486 to complete a simple instruction like ALU reg,reg or ALU reg,im every clock cycle. The 386 needed two clock cycles for this.
* Integrated FPU (disabled or absent in SX models) with a dedicated local bus gives faster floating point calculations compared to the i386+i387 combination.
* Improved MMU performance.

The 486 has a 32-bit data bus and a 32-bit address bus. This required either four matched 30-pin (8-bit) SIMMs or one 72-pin (32-bit) SIMM on a typical PC motherboard. The 32-bit address bus means that 4 GB of memory can be directly addressed.

The Intel project manager for the 80486 was Pat Gelsinger.

In May 2006 Intel announced that production of the 80486 would cease at the end of September 2007. Although the chip had long been obsolete for personal computer applications, Intel had continued production for use in embedded systems.