AMD SC2200 manual Keyboard Controller Registers

32580BCore Logic Module - ISA Legacy Register Space

		Table 6-47. Keyboard Controller Registers
Bit	Description
I/O Port 060h		External Keyboard Controller Data Register (R/W)

Keyboard Controller Data Register. All accesses to this port are passed to the ISA bus. If the fast keyboard gate A20 and reset fea- tures are enabled through bit 7 of the ROM/AT Logic Control Register (F0 Index 52h[7]), the respective sequences of writes to this port assert the A20M# signal or cause a warm CPU reset.

I/O Port 061h Port B Control Register (R/W) Reset Value: 00x01100b

7PERR#/SERR# Status. (Read Only) Indicates if a PCI bus error (PERR#/SERR#) was asserted by a PCI device or by the SC2200.

0:No.

1:Yes.

This bit can only be set if ERR_EN (bit 2) is set 0. This bit is set 0 after a write to ERR_EN with a 1 or after reset.

6IOCHK# Status. (Read Only) Indicates if an I/O device is reporting an error to the SC2200.

0:No.

1:Yes.

This bit can only be set if IOCHK_EN (bit 3) is set 0. This bit is set 0 after a write to IOCHK_EN with a 1 or after reset.

5PIT OUT2 State. (Read Only) This bit reflects the current status of the of the PIT Counter 2 (OUT2).

4Toggle. (Read Only) This bit toggles on every falling edge of Counter 1 (OUT1).

3IOCHK# Enable.

0:Generates an NMI if IOCHK# is driven low by an I/O device to report an error. Note that NMI is under SMI control.

1:Ignores the IOCHK# input signal and does not generate NMI.

2PERR/ SERR Enable. Generate an NMI if PERR#/SERR# is driven active to report an error.

0:Enable.

1:Disable.

1PIT Counter2 (SPKR).

0:Forces Counter 2 output (OUT2) to zero.

1:Allows Counter 2 output (OUT2) to pass to the speaker.

0PIT Counter2 Enable.

0:Sets GATE2 input low.

1:Sets GATE2 input high.

I/O Port 062h	External Keyboard Controller Mailbox Register (R/W)
Keyboard Controller Mailbox Register.
I/O Port 064h	External Keyboard Controller Command Register (R/W)

Keyboard Controller Command Register. All accesses to this port are passed to the ISA bus. If the fast keyboard gate A20 and reset features are enabled through bit 7 of the ROM/AT Logic Control Register (F0 Index 52h[7]), the respective sequences of writes to this port assert the A20M# signal or cause a warm CPU reset.

I/O Port 066h		External Keyboard Controller Mailbox Register (R/W)
Keyboard Controller Mailbox Register.
I/O Port 092h		Port A Control Register (R/W)	Reset Value: 02h
7:2	Reserved. Must be set to 0.
1	A20M# Assertion. Assert A20# (internally).
	0:	Enable.
	1:	Disable.
	This bit reflects A20# status and can be changed by keyboard command monitoring.

An SMI event is generated when this bit is changed, if enabled by F0 index 53h[0]. The SMI status is reported in F1BAR0+I/ O Offset 00h/02h[7].

0Fast CPU Reset. WM_RST SMI is asserted to the BIOS.

0:Disable.

1:Enable.

This bit must be cleared before the generation of another reset.

316 AMD Geode™ SC2200 Processor Data Book