journal 2026-05-05

P99: Harvard I/D map

P99 is the architecture-map rung before the Harvard push. It keeps the P98 RTL behavior, reruns the BusyBox shell profile, and records what the instruction/data split needs to become.

Functional result: PASS. Speed result versus P98: FAIL, as expected for a map rung with no performance RTL change.

metricP98P99
shell window cycles66,055,34566,998,698
post-load cycles221,452,591222,509,604
memory stall cycles59,683,33859,928,278
fetch stall cycles27,286,52627,399,253
load stall cycles10,697,96210,718,661
D-cache background fills377,930379,701

The map says the core already has I-cache and D-cache structures, separate fetch/LSU TLB lookup wires, named memory request classes, and a fetch queue. The missing part is independent instruction and data service. All request classes still collapse into one final mem_valid port.

P100 should split the near-core service into instruction-side and data-side request records while keeping lower shared memory underneath for explicit conflict counting.