KN7000 Techni-chord: software, not silicon

Techni-chord: software, not silicon

Techni-chord is the KN7000’s auto-harmony feature: play a melody with the right hand while a chord is specified (by the auto-play-chord section or a held left-hand chord) and the instrument adds harmony notes underneath the melody, voiced in one of fourteen selectable styles. The user’s manual documents it on page 48; the on-screen TECHNI-CHORD editor offers a style grid and an ORCHESTRATOR selector that picks which part sounds the added notes.

A natural assumption about a device with two custom PCM tone-generator LSIs is that a “harmony” feature might be a capability of that silicon — a note-multiplier or chord mode inside the tone generator. It is not. Reverse engineering the MN10300 firmware shows Techni-chord is implemented entirely in software on the main CPU. The harmony engine detects the chord, computes MIDI note numbers with plain semitone arithmetic, and emits them as ordinary note-ons through the same voice path any other note travels. The tone generators never learn that the notes are “harmony” — they receive ordinary voices.

How it is turned on

Techni-chord is not a mode bit in the tone generator; it is three entries in the firmware’s sound-parameter database (the same key/value store that carries every other panel setting):

Parameter	Meaning
0x8080	Techni-chord on / off
0x8081	harmony style, 0..13 (index into the 14 styles below)
0x8082	orchestrator — which part produces the harmony notes

Pressing the panel TECHNI-CHORD button toggles 0x8080; the TECHNI-CHORD editor’s style grid writes 0x8081; its ORCHESTRATOR rocker writes 0x8082. These are ordinary CPU-side settings — nothing is written to the sound hardware to “arm” harmony.

The harmony-compute path

When a melody note is played with Techni-chord on, the harmony routine at 0x48472EBA runs on the MN10300:

1. Fetch the chord. It calls GetCurrentChord at 0x4844DDF2, which copies the currently specified chord — a 6-byte record {type, root, …} maintained at RAM 0x50000B18 by the auto-play-chord / left-hand chord state — then normalises extended chord types (29–41) to a basic type 1–28 through a 42-entry jump table at 0x485BC3EC.
2. Dispatch by style. It indexes a 14-entry jump table at 0x485BC3B4 with the style number (0x8081), branching to that style’s voicing routine — for example CLOSE at 0x48473051, OCTAVE at 0x484736D4, HARD ROCK at 0x48473703, FANFARE at 0x48473732. Note the style number is not the on-screen grid position — see the corrected mapping below.
3. Compute the notes. Each voicing routine computes its harmony notes’ MIDI note numbers by plain semitone arithmetic — there is no pitch DSP and no reference to sample-zone pitch here. Three families:
   • Chord-tone styles (CLOSE, OPEN 1/2, DUET 1): walk the chord-tone list (RAM 0x5003AB04/05), fold each tone into the octave below the melody, keep tones more than 2 semitones below it (max 4), then re-spread or clamp per style.
   • Matrix styles (DUET 2, COUNTRY, THEATRE, HYMN, BLOCK, BIG BAND BRASS, BIG BAND REEDS): per-style matrices at 0x485BA574–0x485BC3A4 — 28 chord-type rows × 12 interval columns × 1–4 harmony bytes; each harmony note = melody − matrix byte. A shared helper (0x48473766) folds the roots of the symmetric chord types (augmented / diminished) so enharmonically identical chords share columns.
   • Fixed-interval styles (OCTAVE, HARD ROCK, FANFARE): signed pairs at 0x485BC3A4 — these three never read the chord at all, which is why the user’s manual says exactly these three “function even when the keyboard is not split”.
4. Emit as ordinary note-ons. The computed notes are sent as normal note-on events on the orchestrator part (0x8082), so they play through that part’s own patch, volume, effects and the standard voice-allocation path — indistinguishable, to the tone generator, from a note the player pressed.

Because the harmony notes are just note-ons on a normal part, everything that applies to a part applies to them for free: the orchestrator’s sound selection, its transpose and tuning, its reverb / chorus / DSP sends, and the sample-zone-relative pitch pipeline that turns a MIDI note into the tone generator’s internal pitch value.

The fourteen styles — and the parameter order that hides one of them

(Corrected 2026-07-19: an earlier version of this page assumed the style parameter counts in on-screen order, which shifted the example addresses for OCTAVE/HARD ROCK by one routine. It does not — see below.)

The 14 style names live as a string pool at 0x485EC960 in on-screen grid order (the TECHNI-CHORD editor screen, user’s manual page 48). But the style parameter 0x8081 — the value the jump table dispatches on — uses a different, legacy order: the GUI translates between the two through a 14-halfword table at 0x485EC940 (param → grid slot: 0,1,2,4,5,6,7,8,9,10,11,12,13,3). The one style that moves is DUET 1: drawn in grid slot 3, stored as parameter 13, after FANFARE.

param	Style (voicing routine)	added notes
0	CLOSE (0x48473051)	chord tones below the melody, max 4
1	OPEN 1 (0x484731EB)	CLOSE, first note dropped an octave
2	OPEN 2 (0x4847320C)	CLOSE, re-spread by octave shifts
3	DUET 2 (0x48473288)	1 (matrix 0x485BA574)
4	COUNTRY (0x484732F0)	1 (matrix 0x485BAEA4)
5	THEATRE (0x48473358)	2 (matrix 0x485BA6C4)
6	HYMN (0x484733E3)	3 (matrix 0x485BAFF4) — four-part writing with the melody
7	BLOCK (0x48473495)	4 (matrix 0x485BA964)
8	BIG BAND BRASS (0x4847355D)	3 (matrix 0x485BB3E4)
9	BIG BAND REEDS (0x4847360F)	4 (matrix 0x485BBE64)
10	OCTAVE (0x484736D4)	melody +12 and −12 (fixed)
11	HARD ROCK (0x48473703)	melody −5 and −12 (fixed — fourth + octave below)
12	FANFARE (0x48473732)	melody +10 and +5 (fixed — stacked fourths above)
13	DUET 1 (0x484731D0)	1 (CLOSE clamped to its first note)

This corrected mapping is what makes every user-manual statement line up with the code: “big band reeds … adds four harmony notes” (the 0x485BBE64 matrix carries four bytes per column); the manual’s chord-independent trio (“when the OCTAVE, HARD ROCK or FANFARE style is selected, the TECHNI-CHORD functions even when the keyboard is not split”) is exactly the three fixed-interval routines; and “a simple duet which adds one harmony note” is DUET 1. The most likely reason for the odd storage order: earlier models had a 13-style list whose parameter 3 was a single DUET; DUET 1 was appended at the end so stored registration data kept its meaning, while the screen draws it beside DUET 2. The KN6000 firmware embeds the same string pool and the same mapping table.

The full engine — TechniChordCompute, all fourteen voicing routines and their helpers — is now converted to re-assemblable, byte-exact MN10300 source in the kn7000_disassembly project (src/program.s, names in kn7000_manual.sym).

Why this is dispositive — it is not hardware

Two facts settle it beyond the mere presence of a software routine:

• The harmony engine writes zero tone-generator registers. The whole path above touches no sound-hardware I/O — there is no access to 0x98040000 / 0x98050000 (the master / sub tone-generator register ports) anywhere in the harmony computation. It produces note events and hands them to the ordinary voice engine; the register writes that actually reach the tone generators are the same ones used for every other note. A hardware harmony feature would have to configure the tone generator; this one never does.
• The harmony is routed to an arbitrary, user-selectable part with that part’s own patch. 0x8082 lets the player send the added notes to any part — played through whatever sound that part is set to. A note-multiplier built into the tone-generator silicon could not redirect its extra notes to an arbitrary part and re-voice them with a different patch. That flexibility only exists because the notes are computed in software and injected as ordinary note-ons.

Panel control

Techni-chord has one dedicated panel button and one indicator LED, both bound in the control-panel device:

	Physical binding	Part
TECHNI-CHORD button	CPR_SEG1 bit 0x01	SW0
TECHNI-CHORD indicator LED	cpr_led33	D1013 (red)

(See the Control Panel Protocol for the scan-matrix tagging convention.)

Consequence for emulation

Nothing extra is required to emulate Techni-chord. Because it is a pure-software feature that ends in ordinary note-ons, a correct MN10300 running the firmware plus the existing tone-generator note path reproduces it for free — the MAME driver already executes the harmony routine as part of normal firmware execution, and the added notes sound through the same pipeline as any key press. No harmony model, note-multiplier or special tone-generator mode has to be written.

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Footnote — not to be confused with the microphone harmonizer. The symbol HarmOnOffFunc at 0x484D6EA6 and the writes to 0x90204000 belong to the Vocalist Workstation microphone-harmony feature (a real-time pitch harmonizer for the mic input, driven through a MILK class descriptor at 0x4874CFF0) — a separate subsystem from Techni-chord. Techni-chord harmonizes keyboard notes in software as described above and does not use that path.