Phase 002: BBC machine layer (bbc/ package)#3
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Wire mos6502.CPU into a BBC Model B memory map: OS ROM, four sideways ROM banks, SHEILA decoder + 11 stub peripherals (CRTC, ACIA, Serial ULA, Video ULA, ACCCON, System+User VIA, FDC, Econet, ADC, Tube), and the Machine façade (New, LoadOSROM/LoadSidewaysROM, Tick, Reset/ ColdReset, IRQ/NMI/RDY pass-throughs, SetUnmappedAccessHook, CPU, Memory, Snapshot/Restore). 78 deterministic tests on bbc/ cover loaders, Reset vs ColdReset, RAM/OS ROM/sideways-window round-trip, SHEILA routing for every range in FR-008, CRTC index-then-data, VIA mirroring, FRED/JIM open-bus, 4-bank paging, Snapshot/Restore byte-identical round-trip, UnmappedAccessHook semantics, FR-028 no-locks reflection guard. Four golden bus traces locked. OS 1.20 smoke test gated on BBC_OS_ROM (image not redistributed). Gates: 169 tests pass under -race; vet clean; golangci-lint 0 issues; benches ~5.5 ns/cycle with 0 B/op 0 allocs/op (gate ≤6.5 ns/cycle); 96.9% coverage on bbc/ (gate ≥80%). Also update CLAUDE.md (bbc/ package summary), docs/roadmap.md (mark Phase 002 ✅ Complete with bench numbers), and quickstart.md (fix mos6502.Trace + Disassemble usage). Makefile bench target now covers bbc/. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
bbc/package wiringmos6502.CPUinto a BBC Model B memory map: 32 KB RAM, OS ROM, four sideways ROM banks via$FE30latch, SHEILA decoder dispatching to 11 stub peripherals (CRTC, ACIA, Serial ULA, Video ULA, ACCCON, System+User VIA, FDC, Econet, ADC, Tube).Machinefaçade:New,LoadOSROM/LoadSidewaysROM(copy-on-load),Tick,Reset/ColdReset, IRQ/NMI/RDY pass-throughs,SetUnmappedAccessHook,CPU/Memoryaccessors,Snapshot/Restore.Gates
go test -race ./...go vet ./...golangci-lint run ./...BenchmarkTickNoopBenchmarkTickMixedWorkloadbbc/coveragespecs/002-bbc-machine/tasks.md[X]Performance budget SC-006 (≤ ~6.5 ns/cycle) comfortably met.
Test plan
make fmt vet lint testcleango test -race ./...passesgo test -bench=BenchmarkTick -benchmem -benchtime=200ms -run=^$ ./bbc/reports0 B/op 0 allocs/opgo test -coverprofile=… ./bbc/≥ 80%specs/002-bbc-machine/quickstart.md)BBC_OS_ROM=/path/to/os120.rom go test ./bbc/ -run TestBootRealOSROM— asserts 1 000 000 cycles run without firingUnmappedAccessHookorIllegalOpcodeHook(SC-001)Docs
CLAUDE.md— addedbbc/package summary (public API, validation status, bench numbers, known limitations).docs/roadmap.md— Phase 002 marked ✅ Complete with bench numbers and deferred-items note.specs/002-bbc-machine/quickstart.md— fixedmos6502.Trace+Disassembleusage; addedMachine.Memory()accessor referenced by quickstart.Makefile—benchtarget now covers./bbc/.🤖 Generated with Claude Code