Chapter J. Instruction Set
CALL
3-8
[
._0_0
~
data ]
Cycles:
Sta
tes:
Addressing:
Flags:
Summary
of
Logical Operations
2
7
immediate
Z,S,P,CY,AC
AND
produce~
a one bit
in
the result only when the corresponding bits
in
the test data and the mask data are
ones.
OR produces a one bit
in
the result when the corresponding bits
in
either the test data or the mask data arc
ones.
Exclu~ive
OR produces a one bit only when the corrcsponding bits
in
the test data and the mask data are
different; i.e.,
a one bit
in
eithcr thc test data or the mask data - but not both produces a onc bit
in
thc
result.
Example:
AND
1010 1010
0000
1111
0000 1010
OR
10101010
0000 1111
1010 1111
EXCLUSIVE OR
1010 1010
0000
1111
1010 OlOl
The following instruction
is
u'>ed
to
re~et
OFF bit six
of
the byte
in
the accumulator:
ANI
101111118
Since any bit ANDed with d one remains unchanged and a bit ANDed with d zero i,
rc'>t
to
lcro,
thc
ANI
instruction shown above scts bit six OFF and
ledvc~
the othcr', unchangcd. This tcchniquc
is
u,eful when a
program uscs individual bits
a<;
slatus flags.
CALL
Thc CALL
imtruction
combincs functions
of
thc
PUSH
and J\1P
instruction~.
CALL pushcs the
contents
of
the
program
counter
(the address
of
the ncxt sequential instruction)
onto
the stack and thcn jumps to the address
spccificd
in
the CALL instruction.
Edch
CALL il1'.tructioll or one
of
it<;
variant~
implie, thc use
of
a subsequent RET (return)
imtruction.
Whcn a
call hds no
corre~pollding
return, exccss
addres'>c'>
arc built up
in
thc stack.
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