KN7000 Table ROM — Resource Archive

Technics SX-KN7000 — table ROM resource archive

The KN7000’s 4 MB table ROM (mapped at 0x48000000, a mask ROM byte-interleaved across two flash chips) is not code — it is a directory-based resource archive. It opens with a table of little-endian u32 chunk offsets, and each entry points to a tagged resource.

Chunk kinds

Address	Tag / content	Meaning
0x48000000	u32 offset directory	index of all chunks (first chunk at 0x48000200)
0x48035d08	TCMP	the factory rhythm-style container (3 built-in styles, “ Easy 8 Beat “ / “Easy 16 Beat “ / “ Easy Swing “), LibMemCopy‘d to RAM 0x50180000 (MEM_STYLE_AREA) at boot — data, not code; nothing ever calls into that RAM range
0x48040674	TPAD	performance-pad index / parameters
0x4804238c	Technics Pads	accompaniment pad pattern data
0x483e828c	Technics Rhythms	style/rhythm resource index
(throughout)	JFIF JPEG	119 embedded UI/graphics images

Correction. An earlier pass here misread the copy of the TCMP chunk into RAM 0x50180000 as a code overlay being executed (the symbol was once named RamCodeOverlayImage). Both ends of that copy are data: the destination is zeroed by LibMemSet(0x50180000, 0, 0x25800) beforehand, the source is TableRomSeg02PtrSize resolving directory entries 2–3, and nothing in the firmware branches into 0x50180000. The routine and symbol are now named MemStyleAreaLoadFactory / FactoryMemStyleContainer. See kn7000_mame/notes/AUTONOMOUS-STATUS.md (2026-07-20) and kn7000_mame/notes/table-rom-format.md.

The UI graphics are standard JPEGs

Scanning for JPEG streams recovers 119 images, 117 of which decode cleanly with an ordinary JFIF decoder — 52 are 160×120 icons/thumbnails and twelve are full-screen 640×240 reference/help screens. In other words the KN7000 stores its on-screen artwork as ordinary JPEGs and decodes them in firmware. (A long-standing emulation note that “the boot-splash JPEG decodes to garbage” is therefore a software JPEG-decoder bug, not a bad dump or an exotic format — the source stream is valid JFIF.)

Example full-screen reference screens, extracted verbatim from the ROM:

The ORGAN STYLIST list above shows real style names (Swing Tonewheels, Classic B3 Jazz, …) that match the built-in rhythm catalog recovered from the program ROM.

A smaller 240×160 panel graphic:

Reproduce

De-interleave kn7000_table_{even,odd}.rom (out[0::4]=e[0::2]; out[1::4]=e[1::2]; out[2::4]=o[0::2]; out[3::4]=o[1::2]) → 4 MB image; walk the u32 directory at offset 0; extract JPEGs by scanning ff d8 ff e0 → ff d9. See also the firmware images page for the full per-segment breakdown; technical detail in kn7000_mame/notes/table-rom-format.md.