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Push Low Accumulator Onto Stack
PUSH
7-141
Assembly Language Instructions
Syntax PUSH
Operands None
Opcode
0123456789101112131415
0011110001111101
Execution Increment PC, then...
Push all stack locations down one level
ACC(15:0) → TOS
Status Bits None
Description The stack values move down one level. Then, the content of the lower half of
the accumulator is copied onto the top of the hardware stack.
The hardware stack operates as a last-in, first-out stack with eight locations.
If more than eight pushes (due to a CALA, CALL, CC, PSHD, PUSH, TRAP,
INTR, or NMI instruction) occur before a pop, the first data values written are
lost with each succeeding push.
Words 1
Cycles for a Single PUSH Instruction
ROM
DARAM SARAM External
1 1 1 1+p
Cycles for a Repeat (RPT) Execution of a PUSH Instruction
ROM
DARAM SARAM External
n n n n+p
Example PUSH
Before Instruction After Instruction
ACC X 7h ACC X 7h
CC
Stack 2h Stack 7h
5h 2h
3h 5h
0h 3h
12h 0h
86h 12h
54h 86h
3Fh 54h
Cycles