Machine Characteristics - KBC Output Port
This is one of a number of machine-characteristics.
KBC Output Port
This table shows the initial values read using command 0xd0 from the keyboard controller's output port.
Machine | KBC Output Port |
---|---|
Dell Latitude XP 475D laptop. 80486 75MHz. Phoenix BIOS 1.10 | 1100_1000 |
ABIT AB-SM5-A. Pentium MMX 233MHz. Award Modular BIOS v4.51PG | 0100_1001 |
AOpen motherboard. Pentium 3 600MHz. Award BIOS 3.60 | 0100_1001 |
Viglen MPC-L. Geode 399MHz. ION A503 BIOS | 0100_1011 |
Asus EEE 4G netbook. Celeron M ULV 630MHz. AMI ASUS 701 BIOS | 1100_1111 |
Gateway laptop. Dual-core Core 2 T5300 1.7GHz. Phoenix BIOS | 0100_1001 |
Asus M2NPV-VM. Athlon X2 Dual-core 2.3GHz. Phoenix BIOS 1201 | 0000_0001 |
Jetway NC91. Dual-core Atom 1.6GHz. Phoenix-AwardBIOS | xxxx_xxxx |
Notes
- The bits are
- 7 - data out to the keyboard
- 6 - clock out to the keyboard
- 5 - IRQ12 output (PS/2) or input buffer empty signal (pre-PS/2)
- 4 - IRQ1 output
- 3 - clock out to the mouse
- 2 - data out to the mouse
- 1 - output to A20 gate (set to 1 to enable A20)
- 0 - system reset output (set to 0 to reset the machine)
- In all machines which responded the two interrupt outputs read as 0.
- Both clock outputs (to keyboard and mouse) in most cases read as 1.
- The system reset output does not always read as 1. Writing this bit back as read could hang or reset the machine.
page revision: 1, last edited: 04 Nov 2014 15:25