ApplyAttrByte decodes attribute byte idx (0..4) into the currently-selected sprite. Shared by the NextReg $35-$39/$75-$79 path and the port-$57 stream

BankPeekFrom implements the bounds-checked peek logic on top of a backend's Bank() lookup. Backends embed this so their Bank() is the only method they

BankPokeFrom is the symmetric counterpart to BankPeekFrom. The write goes directly into the backend's bank slice, so the running emulator sees the cha

Banner prints the ZX_Go startup banner to stderr in Spectrum rainbow stripes. No-op when stderr is not a TTY.

Clock advances one i_CLK rising edge for line level rxIn. After the call, Avail()/Byte()/FramingError()/ParityError() report this cycle's outputs.

ComposeWideTilemapRow composites the native 640-pixel tilemap over dst, a 640-pixel RGBA row already holding the doubled lower layers.

ContendMemory adds contention delay if the address is in contended memory.

DisableKempstonMouse detaches the Kempston mouse.

DisableZXPrinter detaches the ZX Printer. Any accumulated print rows are dropped — callers who want to keep the bitmap should Save() first.

DivMMCState returns a one-line summary of the divMMC pager state: paged-in, MAPRAM, selected bank, automap on/off.

EFF7Value returns the current $EFF7 latch as it reads back on real hardware: bit 3 = portEFF7Reg3, bit 2 = portEFF7Reg2, all other bits 0. Exposed mai

EjectDisk removes the disk in the given drive, if any.

EnableAudio initializes and starts the audio system. Call this from the application (not tests) after creating the ULA.

FEReadCount returns the monotonic count of port-$FE reads. The fast-load turbo samples this per frame: a high read rate means the CPU is in a tape loa

Finalise consolidates the recording for distribution: removes any intermediate (non-first) snapshot blocks and merges adjacent input recording blocks

Frame ticks any peripheral that needs a per-frame pulse. Call once per emulator frame (50 Hz) after ExecuteFrame + Render. Currently only the ZX Print

GenerateAudio fills buf with one frame of interleaved left/right 16-bit audio from the SAA1099 (buf length should be 2·SamplesPerFrame). The GUI calls

GenerateSamples generates `count` audio samples (mono, signed 16-bit). The caller is expected to upmix to stereo if needed.

GetRAM returns the Multiface RAM data

GetROMTypeName returns a human-readable name for a ROM type

HandleOpcodeRead handles opcode reads that might trigger peripheral actions

HandlePortWrite forwards FDC data writes. Writes to the status port are undefined on the µPD765 (it's read-only) but we report the port as handled so

Handles reports whether the given I/O port is one of the Beta registers.

HardReset applies i_reset = '1' for a cycle: every reset_hard-guarded register returns to its power-on value (ctc_chan.vhd:175,190,266,281).

HasActiveSprites reports whether the sprite layer is wired AND enabled, so the ULA knows whether to run the sprite border pass.

HasMedia reports whether a backing block source is present.

HiResLayer2Active reports whether Layer 2 is in a hi-res mode (NR$70 resolution 1/2). When true the ULA renders the wide Layer 2 path (renderHiResLaye

IEO returns the daisy-chain output (true = chain open below this controller).

IdAt is the exported entry point for walking a track's byte stream to find the next IDAM. Used by external packages (e.g. disciple) that implement the

InjectP loads a ZX81 .P snapshot (a raw dump from $4009, including the saved system variables) and resumes execution at the ROM's LOAD-return entry, s

InsertInterface2Cartridge loads a 16KB .rom file and inserts it into the Interface 2 cartridge slot. On subsequent memory reads in the 0x0000-0x3FFF w

InsertMicrodrive inserts the cartridge file at path into the IF1's drive `slot` (0-based). Requires that EnableInterface1 has already been called.

IntN reports the active-low INT line (true = inactive). /INT is asserted to the CPU when this is false.

IsPagedIn reports whether the divMMC overlay is currently masking memory at 0x0000–0x3FFF. This is the EFFECTIVE state — the FBLabs FPGA core maps the

List returns a snapshot of the current watches in insertion order.

LoadInstalledROM reads filename from the install dir ONLY — it does NOT fall back to any embedded copy. Use this when the question is literally "did t

LoadO injects a ZX80 .O snapshot into mem, starting at $4000.

LoadP injects a ZX81 .P snapshot into mem, starting at $4009. Bytes that would fall outside the 16-bit address space are dropped.

LoadPeripheralROMs loads ROMs for peripheral devices. Each ROM is treated as optional: if the file isn't present in the user's roms/ directory or in

LoadPlus3Disk parses a DSK image and attaches it to the given drive of the +3 FDC (0 = A, 1 = B).

MMUSlots returns the bank index visible in each of the 8K MMU slots. The Z80 has 8 slots of 8 KB; -1 marks "ROM" or "unmapped".

MicrodriveSlotCount returns the number of microdrive slots the Interface 1 hardware supports (8). Exposed via the peripheral manager so UI code can it

MixInto sums all three TurboSound chips into buf, so the Engine satisfies the audio system's AY source (audio.AYSource). Each AY.MixInto adds (saturat

MountSDCard installs a directory-backed SD card on the Spectrum Next harness. Subsequent esxDOS F_OPEN / F_READ / F_FSTAT calls from guest code resolv

New creates a new AudioSystem instance.

NewBus wraps an RTC register model with the bit-banged i2c slave.

NewFIFOP returns a reset FIFO-pointer manager with the given depth.

NewLegacy creates a Memory instance with the legacy interface for compatibility

px per swatch cell → 288×288 grid NewPaletteView builds the widget. provider may be nil (renders an all-black grid until one is set).

NewSounDrive returns a SounDrive with the four channels at mid-scale ($80), matching soundrive.vhd's reset state.

NewWithBreakpoints is New with an externally-supplied shared breakpoint set (pass the emulator's so the telnet and visual debuggers share one store).

NextEntry reads the next directory entry (for directory handles). Returns io.EOF when the directory is exhausted.

PCM_L returns the 9-bit left output (chA + chB), per soundrive.vhd.

PCM_R returns the 9-bit right output (chC + chD), per soundrive.vhd.

PaletteOffset returns the current NR$70 palette offset.

ParseChannels decodes a comma-separated list as used in the `--trace=` flag. Unknown channels return an error so typos don't silently disable a reques

ParseUDI parses a UDI image from a byte slice.

PressCAPSShift sets or releases the CAPS SHIFT bit on the Spectrum keyboard matrix directly. Used to drive extended keyword entry sequences where the

PressKeyShift marks a host key as held down with the host shift modifier active — i.e. the Spectrum CAPS SHIFT bit gets set alongside the base key. Us

ROM returns a read-only view of the loaded ROM bytes. nil if no ROM is loaded.

ROMMappingNR8E reconstructs the NextReg $8E ("Spectrum 128K Memory Mapping") READ value from the live paging ports. Per nextreg.txt lines 870-885 and

Read8 returns the NextReg $41 read-back: the 8 most-significant bits (8:1) of the 9-bit palette value at the current index in the selected (write-targ

ReadBlock copies 512 bytes for the given LBA into dst. dst is guaranteed to be exactly 512 bytes.

ReadSelected returns the value of the currently selected register, used by reads of port 0xFFFD.

RearmFPGABootROM re-enables bootrom mode using the retained image. Models zxnext.vhd:5108-5110: the NR reset block (hard OR soft reset) re-asserts boo

Refresh repaints from the current provider. Reads the provider exactly once so the count label and the rendered sheet always agree, even though the pr

ReleaseKeyShift releases a key that was pressed with PressKeyShift.

RemoveInterface2Cartridge ejects any currently inserted cartridge. Memory reads at 0x0000-0x3FFF fall back to the internal BASIC ROM on the next read.

RenderSpriteSheet tiles pre-resolved sprites into a sheet: each sprite is SpritePixels RGBA values (row-major 16×16), drawn at the given integer `scal

RenderSwatch draws `count` colours into a grid of `cols` columns, each cell `cell`×`cell` pixels, filling every cell with the colour returned by color

Reset reinitialises all three chips and selects chip 0.

Reset resets the CPU to its initial state.

Reset returns the chip to power-on state (all registers clear → silent).

Reset forces the module's registers to their reset values (multiface.vhd :126,141,156,175) and recomputes the outputs.

Reset restores the register file to power-on defaults, leaving OnRead/OnWrite handlers intact. Used by the GUI's "Reboot" menu item so a fresh boot do

Reset returns the ULA to power-on state. The microdrive bus is reset too — see Bus.Reset for what that clears.

ResetWriteLatches drops the half-completed NR$44 pending-pair state. Called from the emulator's Reboot path so a stale half- pair from the previous bo

RestoreMMU re-applies a SnapshotMMU capture via SetMMU, so the slot mapping (and any derived read/write page maps) is rebuilt exactly.

RestorePool copies a SnapshotPool result back into the live pool. Short/nil entries and length mismatches are clamped by copy(), so a snapshot from a

Save writes the accumulated rows to a PNG file. Returns an error if nothing has been printed yet or the file can't be written.

SavePlus3Disk writes the disk in the given drive back to a DSK file.

ScreenImage returns the current rendered screen image. The returned RGBA pointer is owned by the ULA and may be overwritten by the next Render call (i

SetAccessor rewires the backend. Pass nil to disconnect.

SetAllWriteHook installs a callback fired on every successful Write that lands a byte in RAM (logical address + value), regardless of dispatch path. P

SetAutoIncDisable sets the NR$43 bit-7 palette auto-increment-disable latch. When true, Write8/Write9 leave the index unchanged after a write.

SetAutomap enables or disables the automatic-paging mechanism. Disabling without CONMEM (port $E3 bit 7) also drops the currently-mapped overlay so th

SetBorderClip sets NextReg $15 bit 5 ("border clip enable").

SetContentionEnabled toggles ASIC contention (false = the ZX_GO_SAM_NO_CONTENTION A/B mode: no memory or I/O wait states at all).

SetEntryPoints0 updates NextReg $B8 (Divmmc Entry Points 0), reconfiguring which of $0000/$0008/$0038 fetches trigger the overlay. Called from the Nex

SetEntryPoints1 updates NextReg $BB (Divmmc Entry Points 1), reconfiguring the $3DXX trap, $1FF8 page-out, and the ROM-3 fetch hooks ($04C6 / $04D7 /

SetEntryPointsTiming0 updates NextReg $BA (Divmmc EP Timing 0). Cooperates with NR$B9 (epValid0) to gate the RST entry points.

SetEntryPointsValid0 updates NextReg $B9 (Divmmc EP Validation 0). Per zxnext.vhd:2891-2895, gates the RST entry points: RST n only fires when B8[n] A