Rabbit 2000 - Syscall

Rabbit 3000A Instruction
148 Rabbit 2000/3000 Microprocessor
Description
Pushes the current PC onto the stack and then resets the PC to the interrupt vector address represented by
IIR:0x60,whereIIR is the address of the interrupt table and 0x60 is the offset into the table. The address of
the vector table can be read and set by the instructions LD A,IIR and LD IIR,A respectively, where A is
the upper nibble of the 16 bit vector table address. The vector table is always on a 100h boundary.
The push is accomplished by first loading the high-order byte of the PC into the memory location with the
address 1 less than the number in SP. Then the low-order byte of the PC is loaded into the memory location
with the address two less than the number in SP. The value in SP is then decremented twice.
This instruction is implemented in the Rabbit 3000A.
SYSCALL
Opcode Instruction Clocks Operation
ED 75 SYSCALL 10 (2,2,3,3) SP = SP-2; PC = {R,v}
where v = SYSCALL offset
Flags ALTD I/O
S Z L/V C F R SP S D
- - - -