Keyboard scan code

When a key is pressed, a mark code is generated and an IRQ1 interrupt is generated.

When the key is released, a break code is generated and an IRQ1 interrupt is generated.

Therefore: when the A key is pressed and released, two IRQ1 interrupts are actually generated

Break is obtained by setting bit7 of the mark code to 1, that is: break = mark + 0x80

 

1、scan code 集

Here only talk about the keyboard code set set 2 in general daily applications (set 1, set 2 and set 3)

• Basic scan code: Most scan codes are 1 byte.
• Extended scan code:  guided by  e0 , e1  or  e2
• Special PrintScreen/SysRq keys: e0 2a e0 37
• Special Pause/Break key: e1 1d 45 e1 9d c5

 

 

2. Small keyboard scan code table

key	mark（Hex）	break（Hex）	description
NumLock	45	c5	break = mark + 0x80
/	e0 35	e0 b5	The extend scan code is guided by e0
*	37	b7	break = mark + 0x80
-	4a	that	Same as above
7/Home	47	c7	Same as above
8/Up	48	c8	Same as above
9/PgUp	49	c9	Same as above
4/Left	4b	cb	Same as above
5	4c	cc	Same as above
6/Right	4d	cd	Same as above
1/End	4f	cf	Same as above
2/Down	50	d0	Same as above
3/PgDn	51	D1	Same as above
0/Ins	52	d2	Same as above
./Of	53	d3	Same as above
+	4e	this	Same as above
Enter	e0 1c	e0 9c	extend scan code

The <home><Up><PgUp><Left><Right><End><Down><PgDn><Ins><Del> in the keypad is obtained by pressing NumLock and then pressing it.

Therefore, after a <NumLock> mark code is generated, the above-mentioned mark code is generated. Releasing <NumLock> generates another break code.

 

3. Additional key scan code table

key	mark（Hex）	break（Hex）	description
PrintScreen / SysRq	e0 2a e0 37	e0 b7 e0 aa	extend scan code
Scroll Lock	46	c6	Same as above
Pause/Break	e1 1d 45 e1 9d c5	*	Same as above
Insert	e0 52	e0 d2	Same as above
Home	e0 47	e0 c7	Same as above
Page Up	e0 49	e0 c9	Same as above
Delete	e0 53	e0 d3	Same as above
End	e0 4f	e0 cf	Same as above
Page Down	e0 51	e0 d1	Same as above
left	e0 46	e0 c6	Same as above
right	e0 4d	e0 cd	Same as above
up	e0 48	e0 c8	Same as above
down	e0 50	e0 d0	Same as above

Sorry: My understanding of PrintScreen/SysRq and Pause/Break is not thorough. It is not convenient to explain here.

If you know, please leave a message for enlightenment.

 

 

4. Function key scan code table

key	mark（Hex）	break（Hex）	description
<esc>	01	81	scan code
F1	3b	bb	Same as above
F2	3c	bc	Same as above
F3	3d	bd	Same as above
F4	3e	be	Same as above
F5	3f	bf	Same as above
F6	40	c0	Same as above
F7	41	c1	Same as above
F8	42	c2	Same as above
F9	43	c3	Same as above
F10	44	c4	Same as above
F11	57	d7	Same as above
F12	58	d8	Same as above

 

 

5. Scan code table of main keyboard

key	mark	break	key	mark	break	key	mark	break	key	mark	break
~/·	29	a9	<tab>	0f	8f	<scapslock>	3a	ba	<L-shift>	2a	aa
!/1	02	82	q	10	90	a	1e	9e	with	2c	ac
@/2	03	83	w	11	91	s	1f	9f	x	2d	ad
#/3	04	84	e	12	12	d	20	a0	c	2e	ae
$/4	05	85	r	13	93	f	21	a1	v	2f	af
%/5	06	86	t	14	94	g	22	a2	b	30	b0
^/6	07	87	y	15	95	h	23	a3	n	31	b1
&/7	08	88	u	16	96	j	24	a4	m	32	b2
*/8	09	89	i	17	97	k	25	a5	</,	33	b3
(/9	0a	8a	o	18	98	l	26	a6	>/.	34	b4
)/0	0b	8b	p	19	99	:/;	27	a7	?//	35	b5
_/-	0c	8c	{/[	1a	9a	"/'	28	a8	<R-shift>	36	b6
+/=	0d	8d	}/]	1b	9b	<Enter>	1c	9c	<L-ctrl>	1d	9d
|/\	2b	ab							<L-alt>	38	b8
<backspace>	0e	8e							<space>	39	b9
									<R-alt>	e0 38	e0 b8
									<R-ctrl>	e0 1d	e0 9d

 

若输入字符“ABCD”有两种方法

（1）按下 <CapsLock> 键后，再输入 abcd 键，再按 <CapsLock> 键

这样会产生一个 <CapsLock> 键 mark 和 break 码，然后依次是 abcd 的 mark 和 break 码， 最后是 <CapsLock> 的 mark 和 break 码

 

（2）按着 <L-shift> 或 <R-shift> 不放，再按 abcd 键，再放开 <L-shift> 或 <R-shift> 键

这样会产生一个 <L-shift> 或 <R-shift> 键的 mark 码，然后依次是 abcd 的 mark 和 break 码，最后是一个 <L-shift> 或 <R-shift> 键的 break 码