TK2633 Lecture6 Control Instructions
TK2633 Lecture6 Control Instructions
TK2633 Lecture6 Control Instructions
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OBJECTIVES
locations.
u CALL instructions
u Allow a group of instructions (subroutine) to be
u Positive / minus
SUBROUTINES STACK(before)
CALL COMP
1000
?
?
()u*+,($$,-
STACK
20 FFFF
05 FFFE
REGISTERS
A 01
PC 2040
SP FFFE
u
!+"u 3
!+"u2 3
+"u3 3
!!
0
!
+"u
u The RIM instruction (read interrupt mask) reads the SID pin
(serial input data), the masks, interrupt pins, and the
interrupt enable status.
u The RIM instructions will read the information listed in Table
6-9 into the accumulator.
u The STC and CMC instructions set carry and complement carry,
respectively.
u The HLT (halt) instruction halts execution until either a system reset or
an interrupt.
u The 8085A contains five interrupt inputs (TRAP, RST a.5, RST 6.5, RST
5.5, and INTR) and two serial data pins (SID and SOD).
u The RIM (read interrupt masks) and SIM (set interrupt masks)
instructions control the interrupt structure of the 8085A and the serial
data pins.
u El (enable interrupts) and DI (disable interrupts) turn all the interrupts
on and off except TRAP, which can never be disabled. The RST pins
may still be disabled after an El, if the mask bits are set.