Chapter
3.
Instruction
Set
SHLD
is
one
of
the instructions provided for saving the contents
of
the
Hand
L registers. Alternately, the H
and L data can
be
placed
in
the D and E registers (XCHG instruction) or placed on the stack (PUSH and XTHL
instructions) .
0
0
1
0
0 0
1
0
low addr
high
addr
Cycles:
5
States:
16
Addressing:
di
rect
Flags: none
Example:
Assume
that
the
Hand
L registers contain
OAEH
and 29H, respectively. The following
is
an illustration
of
the
effect
of
the SHLD
IOAH
instruction:
Memory Before SHLD
Memory After SHLD
MEMORY ADD
RE
109
lOA
00
00
00 29
10
0
B
o
AE
SS
IOC
00
00
SIM
(81085
PROCESSOR
ONLY)
SET
INTERRUPT
MASK
SIM
is
a multi-purpose instruction
that
uses the current contents
of
the accumulator to perform the following
functions: Set the interrupt mask for the
8085's RST5.5, RST6.5, and RST7.5 hardware interrupts; reset
RST7.5'<,
edge sensitive input; Ind
output
bit 7
of
the accumulator to the Serial
Output
Data latch.
Operand
SIM
Operands are not permitted wi'h the
SIM
instruction. However, you must
be
certain to load the desired bit
configurations into the accumulator before executing the
SIM
instruction.
SIM
interprets the bits
in
the accumu·
lator
as
follows:
3-59
To Next Page
Loading...
