MCP Bizhawk vs Unity MCP

bizhawk_read8

PURPOSE: Read an unsigned 8-bit byte from emulator memory at the given address. USAGE: Use for single-byte status flags, counters, and 8-bit fields. For 16- or 32-bit values use bizhawk_read16/read32 (one call instead of multi-byte assembly); for spans of more than ~4 bytes use bizhawk_read_range (one round-trip instead of N frame-latency hops). BEHAVIOR: No side effects — pure read. Reads work the same way whether emulation is paused or running. Returns an error if the named domain doesn't exist, the address is out of range for the domain, or the loaded core doesn't expose memory.read_u8. RETURNS: Single line 'ADDR_HEX: VAL_DEC (0xVAL_HEX)', e.g. '0x09C6: 99 (0x63)'.

bizhawk_read16

PURPOSE: Read an unsigned 16-bit little-endian value from emulator memory at the given address. USAGE: Use for 16-bit fields (most game-state values: HP, score, coordinates). For single bytes use bizhawk_read8; for 32-bit values use bizhawk_read32; for non-aligned spans or big-endian fields use bizhawk_read_range and decode the bytes yourself (this tool always interprets bytes as little-endian regardless of the target system's native endianness). BEHAVIOR: No side effects — pure read. Reads two consecutive bytes (low byte at `address`, high byte at `address+1`) and combines them as little-endian. Returns an error if the named domain doesn't exist, address+2 exceeds domain size, or the core doesn't expose memory.read_u16_le. RETURNS: Single line 'ADDR_HEX: VAL_DEC (0xVAL_HEX)'.

bizhawk_read32

PURPOSE: Read an unsigned 32-bit little-endian value from emulator memory at the given address. USAGE: Use for 32-bit fields (timestamps, large counters, pointers on 32-bit systems, RGBA colors). For 8/16-bit reads use bizhawk_read8/read16; for big-endian or unaligned multi-word reads use bizhawk_read_range and decode yourself. BEHAVIOR: No side effects — pure read. Reads four consecutive bytes starting at `address` and combines them as little-endian (LSB at `address`, MSB at `address+3`). Returns an error if the domain doesn't exist, address+4 exceeds the domain, or the core lacks memory.read_u32_le. RETURNS: Single line 'ADDR_HEX: VAL_DEC (0xVAL_HEX)'.

bizhawk_read_range

PURPOSE: Read a contiguous range of bytes from emulator memory as a hex dump. USAGE: Use for >4 bytes (one round-trip vs N frame-latency hops). Max 4096 bytes/call (BizHawk serialization limit); chunk larger reads in 4 KiB. Powers the two-snapshot RAM-hunt workflow (snapshot before/after a known change, diff for matching deltas). BEHAVIOR: No side effects — pure read. Returns an error if domain is unknown, length is out of 1-4096, or address+length exceeds the domain. RETURNS: 'ADDR_HEX [N bytes, DOMAIN]:' header + space-separated 2-digit uppercase hex bytes.

bizhawk_write8

PURPOSE: Write a single unsigned byte (0-255) to emulator memory at the given address. USAGE: Use for single-byte cheats, debug pokes, and game-state mutations (give a player N lives, unlock a flag, set a counter). For 16/32-bit values prefer bizhawk_write16/write32 (single call instead of byte-at-a-time); for spans use bizhawk_write_range. To seed cart save RAM realistically (with proper MBC behavior), prefer bizhawk_load_state with a pre-prepared .State file rather than poking SRAM bytes here. BEHAVIOR: DESTRUCTIVE: overwrites whatever was at `address` with no undo (snapshot via bizhawk_save_state first if you need rollback). The write is direct memory access — bypasses MBC bank switches, cartridge mapper side-effects, and DMA semantics — so it cannot be used to emulate cartridge hardware. Returns an error if the domain is unknown, address is out of range, value < 0 or > 255, or the core lacks memory.write_u8. Works whether emulation is paused or running. RETURNS: Single line 'Wrote VAL_DEC (0xVAL_HEX) → ADDR_HEX (DOMAIN)'.

bizhawk_write16

PURPOSE: Write an unsigned 16-bit little-endian value to emulator memory at the given address. USAGE: Use for 16-bit cheats and pokes (HP, score, coordinates). For single bytes use bizhawk_write8; for 32-bit use bizhawk_write32; for big-endian fields, byteswap and use bizhawk_write_range; for cart save RAM seeding, use bizhawk_load_state. BEHAVIOR: DESTRUCTIVE: overwrites two bytes (low byte at `address`, high byte at `address+1`) with no undo. Direct memory write — no MBC/mapper/DMA mediation, see bizhawk_write8 notes. Returns an error if the domain is unknown, address+2 exceeds the domain, value < 0 or > 65535, or the core lacks memory.write_u16_le. RETURNS: Single line 'Wrote VAL_DEC (0xVAL_HEX) → ADDR_HEX (DOMAIN)'.

bizhawk_write32

PURPOSE: Write an unsigned 32-bit little-endian value to emulator memory at the given address. USAGE: Use for 32-bit cheats and pokes (timestamps, large counters, pointers on 32-bit systems). For 8/16-bit values use bizhawk_write8/write16; for big-endian layouts byteswap and use bizhawk_write_range. BEHAVIOR: DESTRUCTIVE: overwrites four bytes starting at `address` with no undo (snapshot via bizhawk_save_state first if you need rollback). Direct memory write — bypasses MBC/mapper/DMA, see bizhawk_write8 notes. Returns an error if the domain is unknown, address+4 exceeds the domain, value < 0 or > 4294967295, or the core lacks memory.write_u32_le. RETURNS: Single line 'Wrote VAL_DEC (0xVAL_HEX) → ADDR_HEX (DOMAIN)'.

bizhawk_write_range

PURPOSE: Write a contiguous byte sequence to emulator memory starting at the given address. USAGE: Use whenever you're seeding more than ~4 bytes — one round-trip vs N frame-latency hops compared to looping bizhawk_write8. Maximum 4096 bytes per call (BizHawk serialization limit); for larger writes, batch in 4 KiB chunks. Useful for installing cheat tables, patching code blocks, restoring a captured byte window after experiments, and writing big-endian multi-byte values (byteswap them yourself first). For cart save RAM seeding with proper MBC semantics, use bizhawk_load_state instead. BEHAVIOR: DESTRUCTIVE: overwrites N bytes starting at `address` with no undo. Direct memory write — bypasses MBC/mapper/DMA, see bizhawk_write8 notes. Bytes are written sequentially address, address+1, ..., address+N-1. Returns an error if the domain is unknown, address+N exceeds the domain, the array contains a value outside 0-255, or the array length is < 1 or > 4096. RETURNS: Single line 'Wrote N bytes → ADDR_HEX (DOMAIN)'.

bizhawk_search_memory

PURPOSE: Find every address in a memory domain whose value equals a target — a Cheat-Engine-style value scan with iterative narrowing. USAGE: Two modes. FIRST scan — omit `addresses`: sweeps the whole domain (or the [start, start+length) window you give) and returns matching offsets. NEXT scan — pass `addresses` (the offsets a prior scan returned): keeps only those that STILL equal `value`, the classic 'the value changed to X — which of my candidates match now?' narrowing. Typical RAM hunt: search a known value (lives=3) → play until it changes → search the new value passing the prior addresses → repeat until a handful remain, then poke them with bizhawk_write*. Pick `width` to match the field size; leave `aligned` true (steps by the width — fast and standard) unless you suspect an unaligned value. BEHAVIOR: No side effects — pure read. A FIRST scan runs synchronously inside one bridge tick and briefly stalls the emulator: it bulk-reads the window in one engine call where the build supports it (cap 16 MiB per scan) and falls back to a byte-by-byte read otherwise (cap 256 KiB per scan — chunk larger windows with start+length). Results are capped at `max_results` (default 200); when more matched, `count` reports the true total and the result is flagged truncated — narrow with a more specific value or range. A NEXT scan is exact over whatever addresses you pass. Returns an error on unknown domain, a value out of range for the width, or a scan window over the cap. RETURNS: A summary line (match count, value, width, bytes scanned) followed by the matching offsets as per-domain hex (0-based — the same offsets the read/write tools take).