Epson S1C63000 Personal Computer User Manual


 
118 EPSON S1C63000 CORE CPU MANUAL
CHAPTER 4: INSTRUCTION SET
PUSH %ir Push ir reg. onto stack 1 cycle
Function: ([(SP1-1)*4+3]~[(SP1-1)*4]) ir, SP1 SP1 -1
Decrements the stack pointer SP1, then stores the content of the ir register (X or Y) into the
addresses (4 words) indicated by the SP1 (SP1 indicates the lowest address).
Code:
Mnemonic MSB LSB
PUSH %X 1111111100001 1FE1H
PUSH %Y 111111110001X1FE2H, (1FE3H)
Flags: EICZ
–––
Mode: Register direct
Extended addressing: Invalid
RET Return from subroutine 1 cycle
Function: PC ([SP1*4+3]~[SP1*4]), SP1 SP1 +1
Loads the 16-bit data (return address) that has been stored in the addresses (4 words) indicated
by the stack pointer SP1 (SP1 indicates the lowest address) into the PC to return from the
subroutine. The SP1 is incremented.
Code:
Mnemonic MSB LSB
RET 11111111110X01FF8H, (1FFAH)
Flags: EICZ
–––