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HT6542B

Holtek Semiconductor Inc
Part Number HT6542B
Manufacturer Holtek Semiconductor Inc
Description Keyboard Controller with PS/2
Published Mar 26, 2005
Detailed Description HT6542B Keyboard Controller with PS/2 Features • • • • • • • • High reliability MOS technology 8042-type host interface...
Datasheet PDF File HT6542B PDF File

HT6542B
HT6542B

Overview
HT6542B Keyboard Controller with PS/2 Features • • • • • • • • High reliability MOS technology 8042-type host interface 6MHz-12MHz operating frequency Communicates with keyboard directly Provides enhanced Gate A20 switching Support PS/2 compatible mouse Auto-detect AT and PS/2 motherboard Support 40 pin DIP and 44 pin PLCC packages General Description The HT6542B is a keyboard controller developed by Holtek with a 4-bit microprocessor.
It is pin-to-pin compatible with Intel 8042 keyboard controller used in IBM PC’s.
PC manufacturers need not modify any printed wiring layout when using the HT6542B in lieu of the Intel 8042 based keyboard controller.
Furthermore, the HT6542B can support a system clock speed of up to 12MHz.
The HT6542B can detect the motherboard type automatically, therefore it can be employed on both of AT and PS/2 motherboard.
Pin Assignment 40 Pin DIP package 44 Pin PLCC package 1 30th Nov ’95 HT6542B Block Diagram Pin Description Pin No.
(DIP) 1 2,3 4 5,7,11,25 6 8 9 2 3,4 5 1,6,8,12,13, 23,29,34 7 9 10 Pin No.
(PLCC) Pin Name KBCI OSCI,OSCO RES NC CS RD A0 I/O I I I — I I I Pin Descriptions Keyboard clock input pin System clock input pin, to generate internal oscillator signal Low level to reset HT6542B.
After RES goes to high level HT6542B needs 10ms to initial internal circuit No connection Host-interface chip select, active low Host-interface read signal, active low Host-interface address select input.
When high, it selects the command/status registers; when low it selects the data register 2 30th Nov ’95 HT6542B Pin No.
(DIP) 10 12~19 20 21 22 23 Pin No.
(PLCC) 11 14~21 22 24 25 26 Pin Name WR D0~D7 VSS RC A20 P22/MSDO I/O I Pin Descriptions Host-interface write signal, active low Host interface data bus.
An 8-bit bi-directional port I/O for data transfers between the host CPU and the HT6542B — O O Circuit ground Host-reset control signal output Gate A20 control signal output General purpose input/output pin for AT I/O mot...


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