Troubleshooting and Repair 6-21
External Keyboard Check
PS/2 Mouse Interface Check
12
Check Keyboard
Data
Check U23
Pin 7 (EXT1DATA)
Check Keyboard
Clock
Check U23
Pin 4 (EXT1CLK)
Check IRQ signal
Check U23
Pin 23 (IRQ1)
END
NO
YES
NO
NO
YES
YES
13
Check Mouse Data
Check U23
Pin 8 (EXT2DATA)
Check Mouse Clock
Check U23
Pin 5 (EXT2CLK)
Check IRQ signal
Check U23
Pin 22 (IRQ12)
END
NO
YES
NO
NO
YES
YES