80386 Early Start Memory Access
A developer details the implementation of 'Early Start' memory access optimization in an FPGA-based 80386 processor core. By replicating Intel's original microcode techniques, the project achieved significant performance gains in legacy software like Doom.
Why it matters
This work demonstrates how historical hardware optimization techniques remain relevant for modern FPGA emulation and retro-computing performance.
When Intel designed the 80386, they gave it a trick for hiding memory latency: Early Start . Instead of waiting for an instruction to reach its memory micro-op, the 386 begins the next instruction's address work — effective address, segment relocation, the bus cycle — in the last cycle of the current instruction. Intel put it at about 9% of overall performance. It is also the source of the POPAD bug.
Technical documentation of hardware engineering with no political or social agenda.
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