IsInvisible returns whether the Multiface is in stealth mode

IsPlaying returns whether the tape is playing.

LoadTZX loads a TZX file into the tape player. TZX is a more comprehensive tape format than TAP, supporting: - Standard speed data blocks (ID 0x10) -

NewInterface returns a Beta interface with a fresh, diskless WD1793.

NewWD1772 returns an idle controller with no disk.

PixelAt reports whether the pixel at (x, y) is ink.

ScreenMode returns the active SAM screen mode 1-4 (VMPR bits 5-6 + 1).

ScreenText returns the contents of the Spectrum text-mode screen as a 24-line string. Each line is 32 characters wide, padded with spaces. Lines are s

VisibleScreenPage returns the physical RAM page holding the displayed image. Modes 3/4 use a 24 KB bitmap over two pages, so the page is forced even.

WireReset wires NextReg $02 (Reset). Per the SpecNext wiki at https://wiki.specnext.dev/Next_Reset_Register the register acts as a "sticky" reset-reas

Write serializes the file to a fresh byte slice. The output starts with the 10-byte RZX header and contains every block in f.Blocks in order. The func

floatingBusByte computes the value an unattached IN returns based on the current scanline / column timing. Implements the canonical algorithm document

rdAddr fetches a 16-bit little-endian operand at PC through two contended read cycles (lo then hi), advancing PC by 2.

CB instruction helper methods

runOpcodeWithSetup is like runOpcode but lets the test prime the CPU/memory state first.

setFrameRel positions the machine so statusByte sees the given frame-relative T-state.

AssertNMIButton latches button_nmi (divmmc.vhd:110-111): a divMMC NMI has been asserted (NR$02 bit 2 / the divMMC NMI button). It arms the $0066 NMI a

ClearConfigMode exits the Next config-mode window. Called from the NextReg $03 OnWrite handler when guest code installs a real machine personality (bi

Cursor returns the current write cursor (for debugging / tests).

Last returns the last n entries in chronological order (oldest first, newest last). n is clamped to the number of entries currently stored. Returns a

Len reports the current ring depth. Race-tolerant — value may shift before the caller acts on it.

New returns a freshly-reset Plus3FDC with no disk loaded.

NewHostDir creates a HostDir mount rooted at the given host directory. The directory must exist; subdirectories and files inside it are reachable thro

NewKeyboard returns a keyboard with all keys released.

ReadStatus returns the status register (Beta port $1F read). Reading status clears INTRQ, matching the WD1793.

SaveBytes serialises the snapshot to a byte slice in the requested format. Symmetric counterpart to LoadBytes for the RZX embedding path.

SetIndex installs the palette-write cursor (NextReg 0x40 write). Subsequent value writes auto-increment from here.

SetRAMReadHook installs a debug callback fired on every successful RAM read returned via the Memory.Read path. bank is the 16K SRAM index, addr the by

SetStripFlags toggles NR$6B bit 5 — when set, the per-tile flag byte is omitted from the map and defaultAttr is used.

SetWritePtrLow / SetWritePtrHighAndMode are the NextReg 0x61 / 0x62 writes. 0x61 is the low 8 bits of the 10-bit cursor; 0x62 carries the high 2 bits

Stop stops tape playback.

VideoMemByte reads displayed video memory by linear offset (0-based from the start of the displayed page), spanning into the next page for modes 3/4.

WireCPUSpeed installs the NextReg 0x07 OnWrite handler that drives CPU.SetSpeedSelect from guest writes. The CPU's SpeedMultiplier method returns 1/2/

WriteAttr streams one byte to the current sprite's attributes (port $0057); after a sprite's 4/5 bytes the current-sprite pointer advances.

WriteCommand issues a controller command.

buildSyntheticDSK constructs a minimal but valid DSK image in memory. The geometry mirrors a typical +3 system disk: 2 sides, 40 cylinders, 9 sectors

contentionDelay returns the contention delay for the current T-state position. Turbo speeds: the contention pattern keys off ULA-scale T-states (CPU

createTestROMDir creates a temporary directory with dummy ROM files for testing.

markMem tags ROM and RAM pages with recognisable markers at offset 0.

--------------------------------------------------------------------------- Helpers. -----------------------------------------------------------------

setActive plots an active-display pixel (0,0 = top-left of the screen area), offset into the bordered frame.

snapshotOnBPHit is called from BreakpointCheck after the halt decision is made. Writes the current emulator state to a .szx in the configured director

ByteCounter / CurrentA / CurrentB expose the chip's internal counters (the values the read mask returns): bytes transferred in the current operation a

Decode parses a raw 16-bit instruction word into Instruction. Per the FPGA encoding (device/copper.vhd): - MOVE: bit 15 = 0; bits 14-8 = NextReg inde

DecodeSnapshot is the inverse of EncodeSnapshot: it reads the format identifier off the SnapshotBlock and asks the snapshot package to parse the embed

Drq reports the data-request line (a byte is ready / needed).

Emit serialises e and writes one JSON line. The output object contains the event's struct fields plus a `"kind"` field set to e.Kind(). Concurrent cal

GetBlock parses block N (0-based) into a Block struct. Mirrors libspectrum_microdrive_get_block (microdrive.c:122-148).

HandlePortWrite handles writes to Multiface I/O ports. OUT to the Multiface port re-arms the hardware (IC8b_Q = 1). For MF128/MF3, A7 also controls th

HasROM checks if a ROM is loaded

IsDisciple enabled returns whether Disciple is enabled

KeyMap returns a stored PS/2 keymap entry (read-side; for the keyboard subsystem to consume).

NextBlock returns the bytes of the next tape block (without the leading length word) and advances the block pointer. Used by the fast-load ROM trap. R

ReadPort returns the value for a Beta register read.

RunFrame executes one 50 Hz SAM frame.

Set writes a 9-bit value to the given index. Only the low 9 bits of val are kept.

SetEnabled toggles Layer 2 rendering. When disabled, RenderScanline fills dst with index 0.

SetNMICallback sets the callback function for NMI (Non-Maskable Interrupt) This is used for Multiface red button simulation

SetRegWriter installs the NextReg writer. Required for MOVE instructions to take effect; otherwise they are silent no-ops.

SetSprites attaches the sprite engine. nil unhooks (compositor falls back to Layer-2-over-ULA only).

cmdCrashDetect implements the live `crash-detect` debugger command. Subcommands: crash-detect — show current status crash-detect on

============================================================================ CMD9, 10, 12, 13, 16, 18, 59 command-set coverage (iter 198 — task #113).

mapMountError translates sdcard.* sentinels to esxDOS error codes.

Covers the non-GUI logic in debugger.go — CheckBreakpoint (plain / bank-filtered / conditional), cpuBank, visualCPUState, and cpuStackSource. These al

parseWatchSpec decodes the --watch flag value into a slice of watchEntries. The format is "name:hex,name:hex,...". Names containing a literal colon ar

readRAM reads a byte from the snapshot's 48K RAM address space (0x4000-0xFFFF)

========================================================================= AY envelope shape end-state tests. Each of the 16 envelope shapes (NR$13 /

withEmulationPaused runs fn with the emulation goroutine paused, then restores the previous pause state. Used by RZX start/stop helpers that mutate li

Active returns the currently-selected chip. Port writes through 0xFFFD / 0xBFFD on ModelNext route through this.

BuildFAT32 walks dir and produces a FAT32-LBA image containing every file and subdirectory under it (macOS metadata skipped).