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feat(serial): support disconnected Joybus configuration and local registers

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0xrsydn 2026-10-07 06:36:54 +07:00
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docs/status.md
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@ -85,6 +85,7 @@ Update this file when a feature lands or a limit is removed.
- Raw ROM-file loading with original BIOS boot, terminal diagnostics, and final CPU/step reports.
- Firmware boot initializes BG2/BG3 identity scales for bitmap and affine programs that do not program their own matrices.
- RegisterRamReset supports disabled sound and disconnected serial initialization, including the common `r0=0xff` request.
- Disconnected Joybus selection, local data/status registers, and transmit-pending state without invented remote events or IRQs.
- Direct Sound A/B support timer-driven FIFO playback, stereo digital levels, and DMA1/A or DMA2/B refill blocks.
- PSG pulse channels 1 and 2 support independent nominal frequency/duty playback, length, envelope, status, and stereo mixing. Channel 1 also supports sweep.
- Noise channel 4 supports nominal 7/15-bit generation, divider clocks, shared length/envelope behavior, status, and stereo mixing.
@ -157,8 +158,9 @@ The [serial subset](hardware/serial.md) supports disconnected normal 8/32-bit tr
Internal clocks shift high input at nominal rates, clear busy, and request completion IRQs. External requests retain busy without clock edges.
Disconnected multiplayer exposes child/ready status and 16-bit send/receive registers without inventing transfers or completion IRQs.
Pre-transfer ID is a zero placeholder; receive-write behavior and reset/alias details lack physical-hardware validation.
Connected links, multiplayer transfers, UART, Joybus, GPIO interrupts, and unverified mid-transfer reconfiguration remain unsupported.
RCNT retains inactive bits 8/14 in normal mode. Effective GPIO interrupt enable and Joybus selection remain diagnostic.
Joybus supports local configuration, data latches, and transmit-pending status, without an external master or completion IRQs.
Connected links, multiplayer transfers, UART, Joybus commands, GPIO interrupts, and unverified mid-transfer reconfiguration remain unsupported.
RCNT retains inactive bits 8/14 in normal mode and bit 8 in Joybus. Effective GPIO interrupt enable remains diagnostic.
Mapped I/O covers DMA, timers, interrupts, WAITCNT, display control/status, background control/scroll/affine registers, window/effect registers, KEYINPUT/KEYCNT, POSTFLG, and HALTCNT.
Keypad IRQs use a documented polling model; hardware retrigger edges and asynchronous input timing remain unverified.
STOP implements keypad wake only. Serial/Game Pak wake sources, oscillator restart delays, and exact wake timing remain unimplemented or unverified.
@ -174,7 +176,9 @@ It also accepts an external-clock serial request without inventing clock edges o
It now also completes internally clocked normal transfers and selects idle multiplayer mode.
With explicit `--rtc` selection, it also passes Game Pak GPIO configuration and RTC calendar reads.
With `--save-type flash128`, it also passes Flash identification and reaches a later startup check.
It next stops at Joybus mode selection (`0x04000135`, PC `0x082deeca`). Flash writing and persistence remain unimplemented.
It now passes disconnected Joybus setup and completes a bounded 600-frame native run without a diagnostic error.
This run uses no scripted input or pixel assertions; menu progress and gameplay remain unverified.
Flash writing and persistence remain unimplemented.
Without `--rtc`, cartridge GPIO writes still return read-only diagnostics.
No title-screen, gameplay, or audible-game compatibility is established.
See [the startup result](research/emerald-reset.md) for the bounded run and next investigation.