Port helpers expressed in WD1772 register terms.

HandleKeyWithModifiers processes a key with explicit modifier information.

NewBank constructs a Bank with all eight palettes initialised to zeros.

SetVMPR stores the video register (only bits 0-6; RXMIDI is read-only) and re-evaluates which sections are displayed. It does not change the CPU map.

createZ80NTestCPU returns a Z80N-variant CPU sharing the 48K memory backing used by the existing ED tests, for unit-testing Z80N opcodes in isolation

--------------------------------------------------------------------------- Phase / handshake helpers. -----------------------------------------------

DE returns the DE register pair.

Drive returns a pointer to the i-th drive (0-based). Out-of-range indices return nil.

RunFrames executes n full emulator frames synchronously on the calling goroutine. Each frame runs the CPU for TstatesPerFrame T-states, renders the sc

Helper to create test ROM files

Index returns the current write cursor.

Mount attaches an image to a drive (0..3). A nil image ejects.

New creates a new AY instance with all registers cleared. The noise LFSR powers up all-zeros, matching the FPGA core (audio/ym2149.vhd:111); the feedb

New constructs a tilemap reader. Disabled by default; clip window defaults to the full area ({0, 0x9F, 0, 0xFF} per the FPGA reset). The dispatcher wr

WritePatternByte streams one byte to the current sprite-pattern cursor (port $005B, auto-incrementing).

activeAt reads a pixel in active-screen coordinates (0,0 = top-left of the 512×192 display area inside the border).

loadTestDisk parses the standard synthetic DSK and returns it.

RedirectConfig points install.Path() at a fresh temp directory for the duration of the test by setting ZX_GO_NEXT_ROM_DIR. Returns the resolved path s

ir returns the I:R register pair value — the address the Z80 places on the bus during internal (no-MREQ) machine cycles, i.e. the value the ULA conten

CPU returns the underlying Z80. Tests that need to peek at register state directly can use it; most tests should stick to the higher-level Memory / Sc

New returns a fresh DMA with no transfer queued.

New constructs a Layer 2 reader backed by the given memory bus. Disabled by default — guest code (or test code) flips it on when ready.

RenderScanline writes the sprite layer's contribution to one row of the active display region. dst is Width bytes of palette indices; the function ove

Covers the live `crash-detect` command dispatcher and its status / enable / disable / set sub-handlers. enable/set wire a pre-fetch hook onto a real C

NewDisciple creates a new DISCiPLE interface.

SelectedSprite returns the current attribute-write cursor.

writeDisplay sets a byte in the display page (page 0 at reset / VMPR 0).

IsMMUOverridden reports whether the given 8K slot was last written through the MMU rather than through classic paging. Exposed mainly for tests; produ

NewFDC returns an idle controller with no disks mounted.

ReadData returns the next byte from the FDC. The CPU reads this from port 0x3FFD on the +3.

SetBC writes the BC register pair.

annotateAddr returns "$XXXX (NAME)" if a symbol exists for the address, else just "$XXXX". Lock-free fast path when no symbols are loaded; takes RLock

Memory routing priority matrix tests (iter 188 — task #109). Verifies the documented priority ordering of read/write dispatch at $0000-$3FFF on Model

synthROM builds a 32K SAM ROM image whose first byte is DI (0xF3, the real ROM's reset entry) with recognisable markers at the start of each 16K half.

BlockCount returns the number of blocks in the tape.

SelectDrive chooses the active drive (0..3).

Helper to create test ROMs

New returns a reset SAA1099 (silent until the master enable bit is set).

NewFromROM validates + splits a raw 32 KB SAM ROM image and builds the machine.

Register installs (or replaces) a handler for the given API number. Pass nil to remove a previously-registered handler.

SetButton presses or releases the given Kempston button bit: bit 0 is right-click, bit 1 is left-click. Pressed drives the bit LOW on the Kempston bus

SetEnabled toggles the divMMC global enable (FPGA i_en). When false the overlay never maps — o_divmmc_rom_en/ram_en are gated to 0 — regardless of CON

crcUpdate is the CRC-16-CCITT update used by the µPD765's address-mark and data-field CRCs. Polynomial 0x1021, initial value 0xFFFF.

setFlagsClear primes flags so all conditional jumps with negated flag conditions (NZ, NC, PO, P) take the FALL-THROUGH path. With F=0: NZ → Z=0 → ta

SetEnabled toggles tilemap rendering (NR$6B bit 7).

Attr returns a pointer to the sprite at idx so callers can read or directly mutate attributes. nil for out-of-range.

Entry-point gating tests. Verifies that the NR$B8 (entryPoints0) and NR$BB (entryPoints1) register bits correctly gate which PC values trigger the di

HandlePortWrite processes an OUT instruction targeting an IF1 port. Returns true if the address decoded to an IF1 port (so the caller stops dispatchin

HandleRead is the memory.PeripheralRead hook. When paged in, 0x0000–0x1FFF reads come from divMMC ROM (or RAM bank 3 if MAPRAM is set — independent of

Insert places the supplied cartridge into drive i, ejecting any existing cartridge first. Calls restart() at the end so the drive is in a consistent s

PageMemoryPlus3 handles the +3/+2A special paging via port 0x1FFD.

PaletteColour returns the RGBA for a 7-bit master-palette index.

SetPatternAddr installs the pattern-RAM write cursor directly, bypassing the port $303B addressing (see SelectSlot) so callers (mainly tests) can targ

SetTileMapBase writes NR$6E.

SetTilesBase writes NR$6F.

SpeedMultiplier returns how much faster than the 3.5 MHz reference the CPU is currently running. Always 1 on non-Next models. On ModelNext, mirrors th

setupFileAPI builds a dispatcher wired to a host-directory SD card mount populated with the given files, plus a fresh CPU and memMap. Returns those pl

Frame finalises the current frame and advances the cursor to the next one. The driver calls this once per emulator frame, AFTER running the CPU for In

GetROM returns the Multiface ROM data

HandleNMI handles Non-Maskable Interrupt (red button press)

Memory reads a single byte from the CPU's memory space at addr. ROM and RAM areas both work; the value reflects the current page mapping (so a 128K te

NextDivMMC returns the currently-wired divMMC pager (nil if none). Exposed so tests and debug tools can poke at pager state without going through the

SetConfigModeRAMPage selects which 16 KB RAM page is visible at $0000-$3FFF when the Spectrum Next "configuration mode" memory map is active. The acti

compressZ80 compresses data using Z80 RLE compression

dsResult reads n result bytes, checking RQM=1/DIO=1/CB=1 before each, and that the FDC returns to the idle command state afterwards.

pkg/memory uncovered-accessor coverage (iter 251). Wraps the 0%-coverage public funcs identified by `go test -cover`: AltROMReg / GetAltROM, ContendP

renderFrame returns the current display image for any machine type. ZX80/ZX81 produce a fresh image per presented frame; the Spectrum/Next path render

Length returns the cartridge length in blocks.

LoadTAP loads a TAP file into the tape player.

New constructs an idle mouse: cursor at 0,0 and no buttons pressed.

New returns a compositor that reads Layer 2 through the given palette bank and Layer 2 reference. Transparency defaults to DefaultTransparency. Any pa

New constructs a fresh IF1 with no ROM loaded and no cartridges inserted. Call LoadROM (or LoadROMBytes) before activating, and use the ULA's Bus to i

SetOnRead installs a read-side computation for the given register. The callback's return value is what reads of the register observe; the backing stor

dsNewFDC builds a DISCiPLE with a real (synthetic) GDOS ROM and an attached in-memory disk so the WD1772 has media to walk. The disk is a small MGT i

HandlePortWrite handles OUT (0xFB). Updates drum state from elapsed cycles, writes pixels up to the current drum position, and starts a new line when

IsROMPaged returns whether the Multiface ROM is paged in

IsROMPaged reports whether the DISCiPLE ROM/RAM is paged in.

Parse reads a .NEX file from any io.Reader. Returns an error (ErrBadMagic) if the magic does not match. Each loading-screen block set in ScreenFlags