w83977eg Winbond Electronics Corp America, w83977eg Datasheet - Page 73

• Manufacturer Part Number: w83977eg
• Description: Winbond Isa I/o W83977ef W83977eg
• Manufacturer: Winbond Electronics Corp America

Continued.
8.5
The KBC implements a hardware control logic to speed-up GATEA20 and KBRESET. This control
logic is controlled by LD5-CRF0 as follows:
8.5.1
KCLKS1, KCLKS0
This 2 bits are for the KBC clock rate selection.
P92EN (Port 92 Enable)
A "1" on this bit enables Port 92 to control GATEA20 and KBRESET.
A "0" on this bit disables Port 92 functions.
NAME
BIT
Hardware GATEA20/Keyboard Reset Control Logic
COMMAND
= 0 0
= 0 1
= 1 0
= 1 1
KB Control Register (Logic Device 5, CR-F0)
ABh
ADh
AEh
C0h
C1h
C2h
D0h
D1h
D2h
D3h
D4h
E0h
FXh
KCLKS1
7
KCLKS0 Reserved Reserved Reserved
KBC clock input is 6 Mhz
KBC clock input is 8 Mhz
KBC clock input is 12 Mhz
KBC clock input is 16 Mhz
Interface Test
Disable Keyboard Interface
Enable Keyboard Interface
Read Input Port(P1) and send data to the system
Continuously puts the lower four bits of Port1 into STATUS register
Continuously puts the upper four bits of Port1 into STATUS register
Send Port2 value to the system
Only set/reset GateA20 line based on the system data bit 1
Send data back to the system as if it came from Keyboard
Send data back to the system as if it came from Auxiliary Device
Output next received byte of data from system to Auxiliary Device
Reports the status of the test inputs
Pulse only RC(the reset line) low for 6 μ S if Command byte is even
6
BIT
00
01
02
03
04
No Error Detected
Keyboard "Clock" line is stuck high
Keyboard "Clock" line is stuck low
Keyboard "Data" line is stuck low
Keyboard "Data" line is stuck high
5
BIT DEFINITION
W83977EF-AW/W83977EG-AW
4
-71-
FUNCTION
3
Publication Release Date: Apr. 2006
P92EN
2
HGA20
1
Revision 1.2
HKBRST
0