vt1200/reference/keyboard-mouse/elkay/docs/keymap.md

Keymap: LK401 → USB HID → veetee

elkay sends the PC key in the same position as each LK401 key, so veetee's stock positional keymap (crates/vt-keyboard/src/default.toml) turns it back into the right DEC key. Other software sees an ordinary PC keyboard.

LK401 keycodes come from lkkbd.c, with the LK401 labels added. Every row is provisional until Phase 3 checks it on the real keyboard.

Top row

LK	LK401 key	HID usage	veetee
56	F1 Hold Screen	F1 3A	hold-screen
57	F2 Print Screen	F2 3B	print-screen
58	F3 Set-Up	F3 3C	set-up
59	F4 Data/Talk	F4 3D	session
5A	F5 Break	F5 3E	break
64–68	F6–F10	F6–F10 3F–43	f6–f10
71	F11 (Esc)	F11 44	f11
72	F12 (BS)	F12 45	f12
73	F13 (LF)	F13 68	f13 ⚠
74	F14	F14 69	f14 ⚠
7C	Help	F15 6A	help ⚠
7D	Do	F16 6B	do ⚠
80–83	F17–F20	F17–F20 6C–6F	f17–f20 ⚠

⚠ On Linux these need the xkb option elkay:fkeys; see host/linux/README.md. Windows needs nothing.

Editing and cursor keys

LK	LK401 key	HID usage	veetee
8A	Find	Insert 49	find
8B	Insert Here	Home 4A	insert-here
8C	Remove	Page Up 4B	remove
8D	Select	Delete 4C	select
8E	Prev Screen	End 4D	prev-screen
8F	Next Screen	Page Down 4E	next-screen
A7	←	Left 50	left
A8	→	Right 4F	right
A9	↓	Down 51	down
AA	↑	Up 52	up

Numeric keypad

LK	LK401 key	HID usage	veetee
A1	PF1	Num Lock 53	pf1
A2	PF2	KP / 54	pf2
A3	PF3	KP * 55	pf3
A4	PF4	KP − 56	pf4
A0	KP −	KP = 67	kp-minus (veetee after 1.7.0)
9C	KP ,	KP + 57	kp-comma
95	Enter	KP Enter 58	kp-enter
94	KP .	KP . 63	kp-period
92	KP 0	KP 0 62	kp0
96–98	KP 1–3	KP 1–3 59–5B	kp1–kp3
99–9B	KP 4–6	KP 4–6 5C–5E	kp4–kp6
9D–9F	KP 7–9	KP 7–9 5F–61	kp7–kp9

The HID Keypad Comma usage (85) would be the obvious choice for KP ,, but xkb gives it KP_Decimal, which collides with KP .. KP + reaches veetee's existing kp-comma binding.

Modifiers and special keys

LK	LK401 key	HID usage	Notes
AE	Shift (left)	Left Shift E1
AB	Shift (right)	Right Shift E5	LK401 mode only
AF	Ctrl	Left Ctrl E0
B0	Lock	Caps Lock 39	Lock LED follows the host's Caps Lock
AC	Alt Function (left)	Left Alt E2	LK401 mode only
B2	Alt Function (right)	Right Alt E6	LK401 mode only
B1	Compose Character (left)	Menu 65	proposed; GNOME Compose Key = Menu
AD	Compose Character (right)	Menu 65	LK401 mode only
BC	<X]	Backspace 2A	veetee: delete
BD	Return	Enter 28
BE	Tab	Tab 2B
D4	Space	Space 2C

Main typing keys (US layout)

LK	Key	HID	LK	Key	HID	LK	Key	HID
BF	` ~ ?	35	C0	1	1E	C5	2	1F
CB	3	20	D0	4	21	D6	5	22
DB	6	23	E0	7	24	E5	8	25
EA	9	26	EF	0	27	F9	- _	2D
F5	= +	2E	C1	Q	14	C6	W	1A
CC	E	08	D1	R	15	D7	T	17
DC	Y	1C	E1	U	18	E6	I	0C
EB	O	12	F0	P	13	FA	[ {	2F
F6	] }	30	F7	\ |	31	C2	A	04
C7	S	16	CD	D	07	D2	F	09
D8	G	0A	DD	H	0B	E2	J	0D
E7	K	0E	EC	L	0F	F2	; :	33
FB	' "	34	C9	< >	64	C3	Z	1D
C8	X	1B	CE	C	06	D3	V	19
D9	B	05	DE	N	11	E3	M	10
E8	, <	36	ED	. >	37	F3	/ ?	38

lkkbd.c calls BF KEY_ESC, but the LK401 has no Esc key; it is probably the ` ~ key. Verify.

Open questions

1. Compose Character. Proposed: Menu (65). veetee's default Compose setting is Local Compose, which on a Linux desktop means the input method's compose. GNOME can use Menu as its Compose key (Settings → Keyboard → Compose Key), so no veetee change is needed.
2. No Esc key. DEC-faithful behaviour is F11. Optionally, a converter layer could make F11 send Esc for desktop use.
3. PF1 is Num Lock. Pressing it toggles the host's Num Lock state. veetee binds both keypad states, so it is harmless there, but other applications will see the keypad change.