SAB80515 Datasheet, PDF (136/270 Pages) Siemens Semiconductor Group – 8-Bit Single-Chip Microcontroller Family

Instruction Set
ACALL addr11
Function:
Absolute call
Description:
ACALL unconditionally calls a subroutine located at the indicated address. The
instruction increments the PC twice to obtain the address of the following
instruction, then pushes the 16-bit result onto the stack (low-order byte first) and
increments the stack pointer twice. The destination address is obtained by
successively concatenating the five high-order bits of the incremented PC, op code
bits 7-5, and the second byte of the instruction. The subroutine called must
therefore start within the same 2K block of program memory as the first byte of the
instruction following ACALL. No flags are affected.
Example:
Initially SP equals 07H. The label ”SUBRTN” is at program memory location 0345H.
After executing the instruction
ACALL SUBRTN
Operation:
at location 0123H, SP will contain 09H, internal RAM location 08H and 09H will
contain 25H and 01H, respectively, and the PC will contain 0345H.
ACALL
(PC) ← (PC) + 2
(SP) ← (SP) + 1
((SP)) ← (PC7-0)
(SP) ← (SP) + 1
((SP)) ← (PC15-8)
(PC10-0) ← page address
Encoding:
Bytes:
Cycles:
a10 a9 a8 1 0 0 0 1
2
2
a7 a6 a5 a4 a3 a2 a1 a0
Semiconductor Group
136