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ZiLOG Z8 Technical Manual

ZiLOG Z8
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4.5
DIRECT
ADDRESSING
(DA)
The
Direct
addressing
mode,
as
shown
in
Figure
4-6,
specifies
the
address
of
the
next
instruction
to
be
executed.
Only
the
Conditional
Jump
(JP)
and
Call
(CALL)
instruct
ions use
this
addressing
mode.
4.6
RELATIVE
ADDRESSING
(RA)
In
the
Relative
addressing
mode,
illustrated
in
Figure
4-7,
the
instruction
specifies
a
PROGRAM MEMORY
TWO·OPERAND
Address
Modes
two's-complement signed displacement
in
the
range
of
-128
to
+127. This
is
added
to
the
contents
of
the
PC
to
obtain
the
address
of
the
next
instruction
to
be
executed.
The
PC
(prior
to
the
add)
consists
of
the
address
of
the
instruction
following
the
Jump
Relative
(JR)
or
Decrement and
Jump
if
Nonzero
(DJNZ)
instruction.
JR
and
DJNZ
are
the
only
instructions
that
use
this
addressing
mode.
RP
INSTRUCTION-~t:~~~r=~!:::r----IPIDIN~TO~~OF------~'~~:2E§~====~
EXAMPLE
POINTS TO
ORIGIN OF
WORKING
REGISTER
GROUP
VALUE USED IN
INSTRUCTION
OPERAND
Figure
4-5.
Indexed Addressing
PROGRAM MEMORY
LOWER
ADDR BYTE
UPPER ADDR BYTE
OPCODE
PROGRAM MEMORY
ADDRESS USED
figure
4-6.
Direct
Addressing
3047-058, 3047-059, 3047-077
PROGRAM MEMORY
~
NEXT OPCODE
DISPLACEMENT
JROR
DJNZ-..
OPCODE
~------------------~
PROGRAM MEMORY
ADDRESS USED
SIGNED
DISPLACEMENT
VALUE
Figure
4-7.
Relative
Addressing
4-3

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ZiLOG Z8 Specifications

General IconGeneral
BrandZiLOG
ModelZ8
CategoryDesktop
LanguageEnglish

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