defaultNextWatch is the canonical Spectrum / Spectrum Next sysvar set worth tracking during boot. Picked to cover BASIC parser state (ERR_NR, FLAGS, C

deviceNextStateIdx is deviceNextState but reads the device's latched request by index (the real im2_int_req).

dirName83 returns the 11-byte 8.3 form of a directory name (no extension).

unwireNextSubsystems strips the Next bus off an emulator, restoring the classic-model state. Called by switchModel when the user picks a classic model

dispatch performs the actual RST 8 trap: read inline parameter, run the handler, pop the stack, advance PC past the parameter. Flag contract: on hand

bit0=1 drive0, bit1=0 side0

dumpMemRanges prints each requested memory range as a 16-byte hex grid via the live Memory.Read path (so MMU paging, alt-ROM redirects, divMMC overlay

dumpState emits a one-shot snapshot of every interesting piece of CPU and Next state. Called from main() when --dump-state is set. Output goes to stdo

effectiveJoystickFor resolves the joystick scheme that should handle arrow keys for a given configured choice and machine model. An unconfigured (None

ejectTRD removes the disk in the given Beta drive.

stored(DEPTH_BITS)

emuDivmmcSnapshotter returns the emulator's divMMC pager as a divmmcRAMSnapshotter, or nil if there is no Next divMMC pager wired (classic models, or

enableInterface1 turns on the Interface 1 — pulls the IF1 ROM from the ROM manager (which loads it from roms/if1-2.rom or the embedded fallback), enab

endSession restores the host paging state and ends the MF session. NOTE: does NOT change romPaged — the MF code's IN instruction will page out the ROM

ensureNRDeltasHook plants the chained tracer once. Cooperates with the existing nr-trace tracer — both can be armed at the same time.

provenance_cmd.go wires the provenance tracker (provenance.go) into the debugger: the `provenance` command (arm / disarm / query a logical address) an

execWriteData walks the current track for an IDAM matching R, then prepares the execution phase to receive sector bytes from the CPU. When the user ha

execute runs the command once all bytes are received and either: - prepares the result phase (commands without execution data transfer) - prepares the

executeInvalid handles the INVALID command — single ST0 byte with IC=10.

extPage returns the read/write pointers for external RAM page p (full 8 bits); pages beyond the installed expansion resolve to scratch.

extractZipFile writes one zip entry to dest, creating parent dirs. The caller is responsible for confining dest to its root — the SD path goes through

fakeReader builds an audioReader wired to as with buffers sized for `samples` mono samples — enough to drive Read() once without touching oto. Lets us

findSubdir scans the directory chain at dirClus for a subdirectory whose 8.3 short name matches name (case-insensitive). Returns its first cluster, or

finishBlock applies the auto-restart-or-stop policy after a transfer's last byte: auto-restart reloads the start addresses and stays armed; otherwise

finishTypeI completes a positioning command with no seek delay and raises INTRQ. The live Type I status bits (TRACK00, SPIN_UP, INDEX, NOT-READY) are

fireBPFirstEntry is called from BreakpointCheck when a hit matches. It self-clears, pauses, optionally snapshots, and logs. Public name because the ho

fixedTime makes record timestamps deterministic so the formatted output is testable.

floppy maps a low-byte port to its WD1772 (drive 1 = 0xE0-E7, drive 2 = 0xF0-F7) and register index (port & 3), or nil if not a floppy port.

flushSDWriteback persists guest SD-image writes to disk when the user opted in via --sd-writeback. The previous file is kept as .bak (see ImageSource.

fmtStackWalk reads up to 16 16-bit words above SP and returns them annotated with the symbol map. Used by the snapshot path for stack traces; exposed

formatCopperDisasm disassembles the Copper program. ins(i) returns the decoded instruction at index i; cursor/mode come from the live Copper. Renderin

formatHex16 formats a uint16 as 4-digit uppercase hex without the "$" prefix.

formatNextRegPanel renders a decoded dashboard of the most useful NextRegs, reading each via rd. Pure function (reader injected) so it unit-tests with

fpgaFrameAddr is the faithful port of the Layer 2 framebuffer-address generator (video/layer2.vhd:145-167). Given the effective raster coordinate (hcE

fpgaSramAddr ports the full SRAM-effective address path (video/layer2.vhd:172-175): the bank-effective mapping that places the framebuffer in the 128K

frameIntPulse models the narrow maskable frame-INT pulse (timing.md §1c) within the frame whose tstate origin is frameStart. The FPGA raises int_ula f

Fuzz the TAP and TZX tape parsers against arbitrary bytes: a malformed tape (bad block lengths, truncated TZX blocks, absurd pilot counts) must be rej

geomFor returns (c_min_hactive, c_max_hblank, c_min_vactive, c_max_vblank) for a tested mode, transcribed from zxula_timing.vhd: 48K 50Hz (:254-270

handleReadBlock dispatches CMD17/18 with the same response framing the CMD9 / CMD10 paths use, byte-for-byte matching the canonical MMC SPI implementa

incrementHead moves the head one byte forward, wrapping around at the end of the cartridge (it's a tape loop). Mirrors increment_head at fuse-1.6.0/pe

Block input operations

installBankSwitchLogger hooks memory.SetBankTracer to emit a slog event for every classic ROM-bank switch and every 8K-MMU slot reassignment. Replace

installWriteWatchers parses --watch-writes and installs a WriteObserver that logs every write to one of the watched addresses. Each event includes the

isContendedAddr returns true if the address is in contended memory (screen RAM).

isScreenLine reports whether a frame-relative scan line falls in the active display (lines 68..259).

joystickKeyForArrow maps a physical arrow / fire key to one of the five joystick directions. Returns -1 if the key is not a joystick input. Index orde

layer2Redirect maps a logical address to the Layer-2 RAM 16K bank + offset it should hit while Layer-2 paging is active, or ok=false when this address

layerColorOf returns an RGBA lookup over the given palette layer.

lddx is LDIX with destination decrement. Source (HL) still advances forward; only DE decrements. Same flag pattern as ldix.

Block load operations

ldix performs one step of the LDIX block: copy (HL) to (DE) unless the source byte equals A; then HL++, DE++, BC--. Flags follow classic LDI: N=0, H=0

linkCluster makes prev's FAT entry point to next, then sets next's FAT entry to EOC.

loadDiscipleDisk opens a file picker for an MGT/IMG/SAD disk image and mounts it in the DISCiPLE's drive (0 = 1, 1 = 2).

loadLoResGolden parses the FPGA-derived golden produced from video/lores.vhd under GHDL. Column order (see the file header and _tools/lores-vhdl-test/

loadPlus3Disk opens a file picker for a DSK image and mounts it in the given +3 FDC drive (0 = A, 1 = B). Refuses (with explanation) on non-+3/+2A mod

loadSAMDisk shows an MGT/SAD/DSK file picker and inserts the chosen image into the given SAM Coupé drive (0 = drive 1, 1 = drive 2). SAM-only.

loadSNA loads a .SNA format snapshot

loadSZX loads a .SZX format snapshot

loadTRDDisk shows a .TRD file picker and mounts the chosen image in the given Beta drive (0 = A, 1 = B), enabling TR-DOS on first use.

loadTilemapGolden reads the FPGA-derived golden (one line per visible (scenario,row,col) where the engine emitted en=1 or pixel!=0), generated from vi

loadZ80 loads a .Z80 format snapshot

logEndOfRunProvenance emits the return-word provenance at the end of a headless run (when --provenance is armed). If the run ended stuck in a trap rea

makeStubCartridge builds a synthetic 16KB Interface 2 cartridge that, when executed from PC=0x0000, writes a known magic byte pattern into RAM at 0x80

markSeekDone latches a "seek complete" status for the given drive so a later SENSE INTERRUPT can pick it up.

markWeakRange marks a range of bytes as weak. Reads of weak bytes return random data each time, modelling copy-protected sectors.

matchChar compares an 8-byte character cell against the 96 printable characters in the Spectrum ROM and returns the matching ASCII code. Returns ' ' (

modelHasFDC reports whether the current Spectrum model has a +3 FDC fitted (i.e. the +3 or the +2A).

modelHasIF1 reports whether the current Spectrum model can have an Interface 1 attached. The IF1 was a 48K-only peripheral — its edge connector and sh

newNexloadMacro builds the macro that loads sdPath (an absolute SD-card path, e.g. "/games/Next/Sonic/sonic.nex"). Timings mirror the verified headles

newRZXTestRig builds a fresh emulator instance backed by stub ROMs. Loads a tiny program at 0x8000 that loops forever: IN A,(0xFE) ; reads from po

newRemoteDebugger spins up the TCP listener and registers the breakpoint check / pre-fetch hook on the CPU. If port is 0 or negative, returns nil (deb

newSamEmulator builds an emulator running the MGT SAM Coupé (pkg/sam). The SAM has its own memory map, I/O/ASIC, keyboard and sound, so the real machi

nextROMsInstalled reports whether the NextZXOS distro ROM is present, so Next boot tests can skip cleanly on a bare checkout.

nonSilent reports whether any sample in buf is non-zero.

nr02Harness wires a dispatcher + memory + CPU exactly like the existing WireReset tests (wire_test.go).

offset returns the byte offset of (cylinder, side, sector) within Data, or an error if any coordinate is outside the image geometry. sector is 1-based

offset returns the byte offset of (cyl, head, sector) — sector is 1-based — and whether it is in range.