In the late 1970s, Intel introduced the 8088 microprocessor, a variant of the 16-bit 8086 processor. IBM’s decision to use the 8088 processor in the IBM PC in 1981 was a pivotal moment in computer history, solidifying the x86 architecture’s dominance. One key feature of the 8086 and 8088 processors was prefetching, where instructions were fetched from memory before needed for faster execution. By reverse-engineering the 8088 from die photos, the blog post uncovers insights into the prefetch circuitry. Despite similarities between the 8086 and 8088, their different bus widths impacted performance and hardware compatibility. Surprisingly, the 8086 was almost a two-chip processor, but prefetching necessitated a single-chip design. The prefetch queue, loader, and microcoding were essential components that optimized instruction execution. Controversially, the 8088’s performance implications due to its narrower bus compared to the 8086 sparked debate among tech enthusiasts.
https://www.righto.com/2024/03/8088-prefetch-circuitry.html