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Format of interrupt sharing protocol interrupt handler entry point

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Offset Size Description

00h

2 BYTEs

short jump to actual start of interrupt handler, immediately following this data block (EBh 10h)

02h

DWORD

address of next handler in chain

06h

WORD

signature 424Bh

08h

BYTE

EOI flag
00h = software interrupt or secondary hardware interrupt handler
80h = primary hardware interrupt handler (will issue EOI to interrupt controller)

09h

2 BYTEs

short jump to hardware reset routine
must point at a valid FAR procedure (may be just RETF)

0Bh

7 BYTEs

reserved (0) by IBM for future expansion

Note:

When chaining to the prior handler, the interrupt handler must perform an indirect jump/call using the address at offset 02h in the ISP header. This permits another AMIS TSR to hook itself into the chain at a position other than as the first handler to receive an interrupt.

See Also:

INT F1/AH=01h"Common ISDN API",INT F1/AH=06h"CAPI",#04068