VT82C596 datasheet(36/96 Pages) ETC

36 / 96 page

VT82C596B

Revision 0.3 June 17, 1999

-30-

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Keyboard Controller Registers

The keyboard controller handles the keyboard and mouse

interfaces. Two ports are used: port 60 and port 64. Reads

from port 64 return a status byte.

Writes to port 64h are

command codes (see command code list following the register

descriptions). Input and output data is transferred via port 60.

A “Control” register is also available.

It is accessable by

writing commands 20h / 60h to the command port (port 64h);

The control byte is written by first sending 60h to the

command port, then sending the control byte value.

The

control register may be read by sending a command of 20h to

port 64h, waiting for “Output Buffer Full” status = 1, then

reading the control byte value from port 60h.

Traditional (non-integrated) keyboard controllers have an

“Input Port” and an “Output Port” with specific pins dedicated

to certain functions and other pins available for

general

purpose I/O. Specific commands are provided to set these pins

high and low. All outputs are “open-collector” so to allow

input on one of these pins, the output value for that pin would

be set high (non-driving) and the desired input value read on

the input port. These ports are defined as follows:

Bit

Input Port

Lo Code Hi Code

P10 - Keyboard Data In

P11 - Mouse Data In

P12 - Turbo Pin (PS/2 mode only)

P13 - user-defined

P14 - user-defined

P15 - user-defined

P16 - user-defined

–

P17 - undefined

–

Bit

Output Port

Lo Code Hi Code

P20 - SYSRST (1=execute reset)

–

P21 - GATEA20 (1=A20 enabled)

–

P22 - Mouse Data Out

P23 - Mouse Clock Out

P24 - Keyboard OBF Interrupt (IRQ1) –

–

P25 - Mouse OBF Interrupt (IRQ 12)

–

P26 - Keyboard Clock Out

–

P27 - Keyboard Data Out

–

Bit

Test Port

Lo Code Hi Code

T0 - Keyboard Clock In

–

T1 - Mouse Clock In

–

Note:

Command code C0h transfers input port data to the

output buffer. Command code D0h copies output port values

to the output buffer. Command code E0h transfers test input

port data to the output buffer.

Port 60 - Keyboard Controller Input Buffer ................. WO

Only write to port 60h if port 64h bit-1 = 0 (1=full).

Port 60 - Keyboard Controller Output Buffer ................RO

Only read from port 60h if port 64h bit-0 = 1 (0=empty).

Port 64 - Keyboard / Mouse Status .................................. RO

Keyboard Output Buffer Full

Keyboard Output Buffer Empty............. default

Keyboard Output Buffer Full

Input Buffer Full

Input Buffer Empty................................ default

Input Buffer Full

System Flag

Power-On Default .................................. default

Self Test Successful

Command / Data

Last write was data write ....................... default

Last write was command write

Keylock Status

0Locked

1Free

Mouse Output Buffer Full

Mouse output buffer empty.................... default

Mouse output buffer holds mouse data

General Receive / Transmit Timeout

No error ................................................. default

Error

Parity Error

No parity error (odd parity received) ..... default

Even parity occurred on last byte received

from keyboard / mouse

KBC Control Register ..........(R/W via Commands 20h/60h)

Reserved

........................................ always reads 0

PC Compatibility

Disable scan conversion

Convert scan codes to PC format; convert 2-

byte break sequences to 1-byte PC-compatible

break codes ............................................ default

Mouse Disable

Enable Mouse Interface ......................... default

Disable Mouse Interface

Keyboard Disable

Enable Keyboard Interface .................... default

Disable Keyboard Interface

Keyboard Lock Disable

Enable Keyboard Inhibit Function......... default

Disable Keyboard Inhibit Function

System Flag ................................................ default=0

This bit may be read back as status register bit-2

Mouse Interrupt Enable

Disable mouse interrupts ....................... default

Generate interrupt on IRQ12 when mouse data

comes in output bufer

Keyboard Interrupt Enable

Disable Keyboard Interrupts.................. default

Generate interrupt on IRQ1 when output buffer

has been written.

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