7

* This specification are subject to be changed without notice.

EM83055H

KEYBOARD ENCODER

9.25.2001

Keyboards ID ( Hex 83AB )

The 2 byte ID is issued to respond to READ ID command. The low byte is sent first, followed by the high byte.

Keyboard buffer Overrun ( Hex 00 or FF )

If keyboard buffer overflows, the overrun code will replace the last byte in the buffer. If the keyboard is using

scan code set 1 , the code is hex FF. For sets 2 and 3, the code is hex 00.

Resend ( Hex FE )

When the keyboard receives an invalid input or any input with incorrect parity, the RESEND command is sent.

Keyboard Scan Code Table

The keyboard contains 3 scan code sets. The system defaults to scan code set 2, but can be switched to set 1 or

set 3 . The following tables show the key numbers and three scan code sets in hexadecimal values. All the keys

are typematics except for the pause key. When a key is pressed down, the make scan code is sent to the

system. When the key is released, its break code is sent. If two or more keys are held down, only the last key

pressed repeats at the typematic rate. Typematic operation stops when the last pressed key is released, even if

other keys are being released or some other keys are still held down.

The following table shows three scan code sets used in the keyboard.

scan code set 1

Key

Make code

Break code

Key

Make code

Break code

`(~)

29

A9

X

2D

AD

102

82

C

2E

AE

203

83

V

2F

AF

304

84

B

30

B0

405

85

N

31

B1

506

86M

32

B2

6

07

87

,(<)

33

B3

7

08

88

.(>)

34

B4

8

09

89

/(?)

35

B5

9

0A

8A

SHIFT_R

36

B6

0

0B

8B

CTRL_L

1D

9D

-(-)

0C

8C

ALT_L

38

B8

=(+)

0D

8D

SPACE

39

B9

BACK SPACE

0E

8E

ALT_R

E0 38

E0 B8

TAB

0F

8F

CTRL_R

E0 1D

E0 9D

Q

10

90

NUM

45

C5

W11

91

(7)

47

C7

E

1292

(4)

4B

CB

R13

93

(1)

4F

CF

T

1494

(8)

48

C8

Y15

95

(5)

4C

CC