parseByteList parses a whitespace- or comma-separated list of hex bytes (with optional $ / 0x prefix) into a slice. Useful for "AA BB CC" or "$10,$20,

parsePressKeySpec parses --press-key. Returns entries sorted by frame for the scheduler to step through linearly.

parseRTCFixed parses ZX_GO_RTC_FIXED (RFC3339). ok=false when unset or malformed (malformed logs a warning).

pauseAndAck transitions a RUNNING CPU to paused and blocks until the headless loop acknowledges. The ack channel is captured in the SAME pauseAckMu cr

queueBusy queues n 0xFF bytes — used to model the variable queueRawDataBlock queues an SDSC-style data block: 0xFE token + exactly len(data) bytes + 2

readPath reads /dir/.../NAME.EXT from a FAT32 image for test verification.

recordPhys stamps the last-writer record for a physical pool cell (16K bank + intra-bank offset). No-op when disabled or before the map is allocated (

renderImage produces the swatch image from the current provider.

restoreNextStateToEmu applies a captured full Next state back to a live emulator. Nil-safe (nil emu or fs is a no-op).

rowBitLow reports whether matrix (row, mask) reads as pressed (active-low).

WZ/MEMPTR on RETI / RETN. Per Sean Young §3.4: ED $4D (RETI) and ED $45 (RETN), plus all their mirror encodings, behave like RET for MEMPTR purposes

R-register increment per M1 cycle. Per Z80 spec, every M1 (opcode fetch) increments the low 7 bits of the R register. Operand bytes are NOT M1 cycles

saveSZXZ80Regs saves Z80 CPU registers as SZX block

16-bit subtract with carry. Undocumented F3/F5 come from the HIGH byte of the result (bits 11 and 13), not the low byte.

scannedBits reports the matrix bits seen through the port-scan interface (so it reflects the typed-character symbol pulse, which Scan overlays). It sc

sharedRegWatches returns the emulator's single shared register-watchpoint set (telnet `watch-reg` + the GUI Watchpoints tab operate on the same instan

signalPauseAck closes the current pauseAckCh and installs a fresh one for the next pause cycle. Called from the headless goroutine when the CPU has ac

sortUint16s sorts a slice of uint16 in ascending order.

tickClock replicates exactly the per-step interrupt/NMI clock bookkeeping that RunFrame performs BEFORE each CPU step (the line-clock NMI pulse and th

updateContention selects the active delay table for the current screen state.

userKeymapPath returns the absolute path to the user's keymap override file under the platform-appropriate config dir: keymap.json inside `<os.UserCon

wireNextSubsystems attaches the Spectrum Next bus onto an emulator constructed with classic (CPU + mem + ULA + kbd + peripherals) wiring. Used by both

withTiming builds an A->B mem transfer that also sends the WR1/WR2 timing bytes (and, if presc != 0, the WR2 prescaler byte), so the duration model ca

writeDirEntry writes a single 32-byte directory entry at index idx inside dirBytes.

writeTempROM writes a file of the given size to a fresh temp directory and returns its path. The content is the byte value (addr & 0xFF) at each offse

writeWavHeader writes a 44-byte canonical PCM WAV header.

writeZ80MemoryBlock writes a compressed memory block in Z80 format

BorderColour returns the current 4-bit border CLUT index (BORDER bits map ((x&0x20)>>2)|(x&7)). The renderer resolves it through the CLUT.

CLUT returns the 16 palette registers (7-bit master-palette indices).

CanEnableInterface1 reports whether the current machine model can host an Interface 1. The IF1 was a 48K-only peripheral; the menu item should be disa

ChannelDAC returns the 8-bit unsigned per-channel digital output level (O_AUDIO_A/B/C) for channel ch (0..2), exactly as the FPGA core's DAC produces

CheckCompetitionSpeed validates that the supplied emulator speed (as a percentage; 100 = real-time) is within CompetitionSpeedTolerance of 100%. Retur

ClearFPGABootROM disables bootrom mode but keeps the loaded image around (cheap to re-enable for a soft reset back into the loader if a peripheral wan

CloseAll closes every open file handle and clears the handle table. Call it on teardown/reset so the host OS releases the underlying file descriptors

ComposeBorderRow paints tilemap content over the border pixels of a 320-wide RGBA row. tilemapY is the row index within the tilemap (0 = top of the fu

ComposeSpriteBorderRow paints sprite pixels over the border-area pixels of a 320-wide RGBA row. frameY is the sprite vcounter for this row (frame-rela

ConfigModeRAMPage returns the latched REG_RAMPAGE value. Exposed for tests; production callers should not need it.

DetectFormat detects the snapshot format based on file extension and content

DisableDisciple disables the Disciple disk interface

DisableInterface1 detaches the Interface 1 — any inserted microdrive cartridges are dropped.

DisableMultiface disables the Multiface interface

DiskPath returns the path of the disk loaded in the given drive.

EjectMicrodrive removes the cartridge from drive `which`.

EjectPlus3Disk removes the disk from the given drive.

GetPage returns a direct pointer to a RAM page. Page indices outside 0..127 return nil. Indices 8..127 return nil on classic models (only allocated fo

FindPC returns every entry whose saved PC equals pc. Useful for "show me every snapshot whose PC was inside the freeze loop".

FormatTrack rebuilds the track at (head, cylinder) from the given sectors, replacing whatever was there — the WD177x Write Track (format) operation. E

GenerateAudioMono fills buf (length SamplesPerFrame) with one frame of the SAA1099 output downmixed to mono — the average of the left and right channe

GetLoadedROMs returns a list of all loaded ROM types

GetPageMap returns the current read/write page map for debugging. Returns [4]int for read map and [4]int for write map. Values >= 16 indicate ROM page

GetStatus returns status information about enabled peripherals

HandlePortRead returns (value, true) if the FDC handled the port; the PeripheralManager uses this to know whether to fall through to other peripherals

HandlePortWrite handles I/O port writes to peripherals

IF1 returns the active Interface 1 device, or nil if not enabled. Used by the UI for cartridge insertion / ejection / write-protect.

Image returns the most recently presented frame (or the in-progress picture if none has been presented yet).

Image renders the picture as a 320×240 RGBA bitmap: the 256×192 active display (ink = black, paper = white) centred in a white border, matching the re

InsertDisk loads a disk image into drive 1 (drive 0) or drive 2 (drive 1).

IsEnabled returns whether the Multiface is enabled

IsEnabled reports whether the DISCiPLE is enabled and not inhibited.

IsRecording reports whether a WAV recording is currently in progress.

JoyMap returns a stored joymap entry.

LoadDiscipleDisk loads a disk image into the specified DISCiPLE drive.

LockSpeedSelect pins the speed selector to v and ignores all subsequent SetSpeedSelect (guest NR$07) writes. Used by the timing diagnostic AND by the

MultifaceActive reports whether the MF overlay is currently paged in.

NewBreakpointsWidget builds the panel. store may not be nil — pass an in-memory implementation if no shared store is needed.

NewHeatmapWidget builds the panel. hist may be nil; call SetHistory once the shared ring is available.

NewImageView builds the panel. minW/minH set the image's minimum display size (it scales with crisp nearest-neighbour).

NewSpriteView builds the widget. provider may be nil.

NewTimeTravelWidget builds the panel. ctl may be nil; call SetController once the backend is available.

NewWatchpointsWidget builds the panel. store may be nil; call SetStore once the shared set is available.

PackIFFIM is the packing helper for HistoryEntry.IFFIM. Kept public so push sites in cmd/zx_go can build entries without duplicating the bit layout.

PageIn pages in the DISCiPLE ROM/RAM and pre-initializes the RAM workspace. Used by the emulator's reboot path to start GDOS cold boot from 0x0000. T

---------------------------------------------------------------------- D40 / D80 (Didaktik 40 / 80) --------------------------------------------------

ParseIMG parses an in-memory IMG image. Same geometry as MGT but sectors are stored in "out-out" order — all of side 0's tracks, then all of side 1's.

ParseSAD parses an in-memory SAD image. SAD is a DISCiPLE / +D variant with an 18-byte "Aley's disk backup" magic followed by a 4-byte geometry header

Peripherals returns the peripheral manager so tests can enable/disable interfaces, insert media, etc.

PlotChar draws display byte b into the character cell at column col (0..31) and text row trow (0..23).

Pos returns the current cursor position. For directories this is the iteration index.

PostFetchHook is a no-op — GDOS pages itself out via port 0xBB.

PreFetchHook pages in the DISCiPLE when the CPU fetches from specific trigger addresses: 0x0001 — second byte of cold boot (re-page after reset) 0x

ReadBlock copies 512 bytes for the given LBA into dst.

Register accessors. Register = port & 3 (0=status/command, 1=track, 2=sector, 3=data).

ReleaseAll lifts every key (used on reset / focus loss).

ReleaseAll lifts every key in the matrix (all bits set = released). Used when the host window loses focus or the machine reboots: the OS stops deliver