Science Fair Project Encyclopedia
Differences between the 80386 and 80486DX include:
- Data/Instruction Cache- An 8192-byte (8k) SRAM built into the processor core, designed to store the most commonly used instructions. The 386 supported an off-chip cache, but this was much slower.
- Pipelining- This allows the processor to handle a LocateFetchExecute each clock cycle. The pipeline is offset meaning the execute step required information from the previous two clock cycles. A locate would be to feed the next fetch, the fetch would be to feed the next execute. The 386 needs to do each step separately.
- Virtual Memory Handler- Hardwired programming to handle swapping memory to hard drive.
- Integrated FPU- Added accelerated high end math functions.
The 486 had a 32 bit data bus. This requires either 4 matched 30 pin simms or 1 72 pin simm
The 486 has a 32 bit address bus limiting it to a 4gb of ram.
The Early 486 machines often used VL bus for video cards and hard drives The bus speed matches the motherboard frequency.
See also: Intel 80486
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