Spectravideo MKI, Сервисное – Техническое руководство

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Symbolic Notation
Symbol
s
z
P /V
H
N
H & N
c
0
X
v
p
r
s
Operation
S ig n f la g .
S
=
1 i f t he
MSB of the r e s u l t
is 1 .
Ze ro f la g . Z
=
1 i f t he r
e s
u
l
t
of t he o p e ra t i on i s
0 .
Par i t y or over f l ow f l a g . Pa r i t y ( P )
and ove r f l ow
( V ) sha re the
same f l a g . Log i c a l opera t i ons
a f f ec t th i s f l a g w i t h
the par i ty
o f the re su l t wh i l e a r i thme t i c
ope r a t i o n s a f f e c t th i s
f lag w i th
the ove r f l ow of the re su l t .
I f
P / V
ho l d s pa r i t y ,
P /V
=
1 i f t he
resu l t of
t he
opera t i on i s
even ,
P /V
=
0 i
f r es u l t i s
o dd . I f
P /V ho
l
d
s ove r f l ow ,
P /V
=
1 i f
the re s u l t o f the
op e ra t ion
produce d an over f low .
Ha l f-ca rry f l a g . H
=
1 i f
the a dd
or subtract ope ra t i on p roduc e d
a c a r r y i n to o r bo rrow f rom
b i t
4
o f
t he a ccumu l a t or .
Add / Subtract f l a g .
N
=
1 i f
the p re v i o u s ope r a t i on
was a
sub t ra c t .
H and
N
f l a g s
are u s e d i n
co n j unc t i on w i th the
dec i ma l a d j u s t
i n s truc t i on ( DAA) to p rope r ly
c o r r e c t
t h e re s u l t i n to packe d
BCD forma t fo l lowing a dd i t ion or subt r a c t ion us i n g ope rands w i th
pack e d BCD forma t .
Ca r ry / L ink f l ag . C
=
1 i f the ope rat i o n produc e d a carry f rom
t he
MSB
of t he operand or resu l t .
The f l a g i s a f f e c t e d accord i ng to the re s u l t of the opera t i on .
The f lag i s unchanged by the opera t i on .
The f l ag i s re se t by the ope rat i on .
The f lag i s s e t by t he ope ra t i on .
The f l ag is a "don ' t care . "
P /V f lag a f f ec te d accord ing t o t he ove r f l ow re s u l t of the
ope ra t i o n .
P /V f l a g a f f ec t e d accor din� to the pa r i t y re s u l t o f the
opera t i on .
Any one o f the CPU reg i s te r s A , B , C , D , E , H , L .
Any 8-b i t loca t i on f or a l l the a dd r e s s ing modes a l lowed for the
pa rt icular i n s t r uc t i on .
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