DR805X Datasheet, PDF (14/79 Pages) Digital Core Design – 8-bit RISC Microcontroller Instructions set details ver 3.10

DR805x Instructions set details
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3. INSTRUCTIONS SET DETAILS
3.1. ACALL
Instruction: 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.
Operation:
(PC)
← (PC) + 2
(SP)
← (SP) + 1
((SP)) ← (PC7-0)
(SP)
← (SP) + 1
((SP)) ← (PC15-8)
(PC10-0) ← page address
Bytes:
2
Cycles:
6
Encoding:
a10 a9 a8 1 0 0 0 1 a7 a6 a5 a4 a3 a2 a1 a0
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