Select them with --save-type eeprom512 or eeprom8k. The part follows GBATEK's
protocol on Game Pak data bit 0: DMA3 sends one bit per halfword, '11' +
address + '0' requests a 64-bit block that reads back after four dummy bits,
and '10' + address + data + '0' writes one. A write reports busy for a nominal
108,368 cycles before the block is stored. 8 KiB parts decode the low 10
address bits. ROMs above 16 MiB map EEPROM only at 0x0dffff00..0x0dffffff.
Bits shift out only inside machine steps, so failed steps roll back. CPU
stores, byte/word accesses, CPU reads during a read-out, and malformed or
overlapping requests are diagnostics. Blocks are stored first-bit-as-MSB,
matching common .sav layouts, and work with save files and save states.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HhfHfHEuzv2AUTd6erW1gU
CPU and DMA reads past the supplied image returned Unmapped and stopped the
machine; a second game's boot code reads 0x09fe20f8 past a 16 MiB image. The
Game Pak shares data lines with the low address lines, so where no chip drives
the bus a read returns the halfword address, (A >> 1) & 0xffff, per lane
(GBATEK; mGBA uses the same pattern).
The chip is the image size rounded up to a power of two. Bytes between a
trimmed image's end and that boundary are unknown and stay diagnostic, as do
host reads and instruction fetches. Two truncation fixtures move into that gap.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HhfHfHEuzv2AUTd6erW1gU
Select it with --save-type sram (SaveDevice::Sram). The array is byte-wide,
starts erased, and repeats every 32 KiB through the 0x0e00xxxx save window.
A CPU byte store is staged and committed when its step completes, so failed
steps roll back and reads later in the step see the byte. Unlike Flash, SRAM
can be read from ROM code. Halfword/word access and DMA stay diagnostic until
the 8-bit bus behavior for those widths is verified.
SRAM shares the save-image API, host save files, and save states. Its device
code is new, so existing save states keep loading.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HhfHfHEuzv2AUTd6erW1gU
Stores to 0x08-0x0c returned ReadOnly and stopped the machine. Hardware ignores
them, and a second game's boot code stores to a ROM mirror. Emulated writes now
pay their bus cost and change nothing. The 0x0d window stays a diagnostic until
EEPROM is modeled there, and host writes stay strict.
Tests that used a ROM store as their failing write now cross an ignored ROM
word into the 0x0d window.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HhfHfHEuzv2AUTd6erW1gU
A core, DMA, rendering, window, or audio error returned before the save was
written, so every completed in-game save since launch was lost. The window now
writes changed bytes on that path too. The diagnostic stays the session error;
a refused or failed write is reported as output. A failed state restore leaves
save memory undefined and is never written. Terminal runs keep the strict rule.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HhfHfHEuzv2AUTd6erW1gU
Machine::save_state and load_state encode the CPU, every RAM, and every device
through Snapshot impls into a versioned, checksummed format. Rejected loads leave
the machine unchanged. The ROM window saves to and loads from one state file
with F5 and F9.
Read strict versioned suite manifests with independent ROM cases, explicit ARM/Thumb checkpoints, register/CPSR/memory assertions, and aggregate step limits. Report every case deterministically and fail on timeouts, STOP, diagnostics, missing files, or mismatches. Keep host JSON dependencies outside the core.
Add an original ARM/Thumb/BIOS suite generator, unit and process-level regressions, and schema/usage documentation. Verified on Darwin arm64 with debug/release workspace and core suites, Clippy, rustdoc, native ROM-window tests, all ten demo smoke tests, repeatable release reports, and a deliberate assertion failure. Independent public hardware-test ROM validation remains next.
Add --rom PATH --window with optional bounded --frames execution. Capture from BIOS boot, pump native events between bounded machine slices, retain frames during STOP, and sample keypad input for wake-up. Share final machine reports with terminal mode.
Add an original file-exportable input ROM, controller and CLI regressions, and opt-in native window tests. Document controls, frame limits, STOP behavior, and compatibility limits. Verified on Darwin arm64: debug/release workspace and core tests, Clippy, rustdoc, native ROM diagnostics, all ten demo smoke tests, and a 60-frame release ROM run.
Load read-only raw ROM files with bounded size checks and original BIOS boot. Require a machine-step budget and report CPU state, STOP, and explicit diagnostics without opening a window. Keep file access in the desktop crate.
Cover argument parsing, Darwin paths, file boundaries, ARM/Thumb execution, DMA/IRQ budgets, HALT/STOP, and error reports. Document limits and usage. Verified on native Darwin arm64: debug/release workspace tests, core-only tests, Clippy, rustdoc, all ten window smoke tests, and a release raw-ROM run.
Move the emulator into crates/gba-core, the original demo programs into
crates/gba-demos, and the minifb frontend into crates/desktop. The binary
is now gameboy-rust. Imports change from gba_rust to gba_core/gba_demos;
no behavior changes.
gba-core has no dependencies. Its integration tests use gba-demos as a
development dependency.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
