10
In most cases, only a very small number of computers require additional wait states. If
the PC 62C seems to be giving incorrect results then try increasing the wait states until
correct results are obtained. If the board still does not produce correct results even after
the maximum number of wait states has been inserted then the PC 62C or the host
computer are defective and should be serviced.
In a standard PC, the interrupt levels are allocated as follows:
Level Level Allocation
IRQ0 System timer
IRQ1 Keyboard
IRQ2/IRQ9 Display Adaptor
IRQ3 COM1 (if installed)
IRQ4 COM2 (if installed)
IRQ5 LPT2 (if installed)
IRQ6 Floppy disk controller
IRQ7 LPT1 (if installed)
IRQ10 Not used
IRQ11 Not used
IRQ12 Used by PS/2 Mouse (if installed)
IRQ13 Coprocessor
IRQ14 Primary IDE Harddisk (if installed)
IRQ15 Secondary IDE Harddisk (if installed)
Table 1.3b: Standard Interrupt Settings
On PC ATs, IRQ2 is used by the system board and any interrupt requests on IRQ2 is
transparently rerouted to IRQ9.
The default IRQ setting on the PC 62C is none. Note that unless the interrupt line is
specifically enabled by software, the interrupt output from the PC 62C is tri-stated (ie:
not connected). It is also tri-stated upon power-up.
