XA User Guide 6-76 4/17/98
CALL Call Subroutine Indirect
Syntax: CALL [Rs]
Operation: (PC) <-- (PC) + 2
(SP) <-- (SP) - 4
((SP)) <-- (PC.23-0)
(PC.15-1) <-- (Rs.15-1)
(PC.0) <-- 0
Description: Causes an unconditional branch to the address contained in the operand register,
anywhere within the 64K page following the CALL instruction.The return address (the address
following the CALL instruction) of the calling routine is saved on the stack. The target address
must be word aligned, as CALL or branch will force PC.bit0 to 0.
Note:
(1) Since the PC always points to the instruction following the CALL instruction and if that
happens to be on a different page, then the called routine should be located in that page (64K)
(2) if the XA is in page 0 mode, only a 16-bit address will be pushed to the stack.
Size: None
Flags Updated: none
Bytes: 2
Clocks: 8/5(PZ)
Encoding:
1 1 0 0 0 1 1 0
0 0 0 0 0 s s s
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