Table des matières
8255 - Programmable Peripheral Interface - PPI (PC,XT, PCjr)
8042 Commands & Responses - (Port 60h)
Commands System Issues to Keyboard (write port 60h)
| Command | Description |
|---|---|
Keyboard Responses to System (read port 60h)
see 8042, MAKE CODES, BREAK CODES, INT 16,3
8042 - Speaker Controller & NMI (AT,PS/2) - Port 61h
This register can be Write and Read
| bit | Description |
|---|---|
| 0 | PIT Channel 2 enabled (see 8253) |
| 1 | Speaker Position 1 : “out” position 0 : “in” position |
| 2 | |
| 3 | |
| 4 | |
| 5 | |
| 6 | |
| 7 | Reset Keyboard status (scan code readed) |
Speaker
8042 Status Register (port 64h read)
8042 Commands Related to PC Systems (Port 64h)
| Command | Description |
|---|---|
| 20h | Read Command Byte: current 8042 command byte is placed in port 60h. |
see <A HREF=“keyboard_commands.html”>KEYBOARD COMMANDS</A> for information on programming the keyboards internal microprocessor