Spectravideo SVI 318 Service – Technical Manual page 67

Symbo l ic Notation
Symbo l Operat ion
s
S i g n f l a g .
z
Z e ro f l a g .
P a r i t y o r over f l ow f l a g .
P / V
same f l a g .
o f the re su l t wh i l e a r i t hme t i c
the ov e r f l ow of the re s u l t .
r e s u l t of
P /V ho
p roduce d an over f l ow .
H Ha l f-ca rr y f l a g .
a c a r r y i n t o o r bo r row f rom
N
Add / S u b t r a c t f l a g .
sub t ra c t .
H and
H & N
i n s t r uc t i on ( DAA) to p ro pe r ly
BCD forma t f o l l o w i n g a dd i t i o n or s u bt r a c t i o n us i n g ope r a n d s w i th
pack e d BCD f o rma t .
c
Ca r ry / L i nk f l ag .
t he
The f l a g i s a f f e c t e d accor d i ng to the re s u l t of the o p e ra t i on .
T he f lag i s unchang e d by t he o p e ra t i on .
0 The f l ag i s re se t by the op e r a t i on .
T he f lag i s s e t by t he ope ra t i on .
X The f l a g i s a "don ' t c a re . "
v
P /V f lag a f f e c te d a c c or d ing t o t he ove r f l ow re s u l t o f the
ope ra t i o n .
p
P /V f l a g a f f ec t e d accor d i n � to the pa r i t y re s u l t o f t he
o p e r a t i on .
r
Any one o f the CPU re g i s t e r s A , B , C , D , E , H , L .
s
Any 8-b i t l o c a t i on f or a l l t he a dd r e s s ing modes a l lowed for t he
pa r t i c u l a r i n s t r uc t i on .
1 i f t he
S
=
Z 1 i f t he r
=
Log i c a l o p e r a t i o n s
o p e r a t i on i s
t he
d P /V
l s ove r f l ow ,
H
=
N
N f l a g s
a r e u s e d i n
C
=
of t he o p e r a n d or r e s u l t .
M S B
4 . 34
M S B of the r e s u l t is 1 .
t
e su o f t he o p e r a t i on i s
l
P a r i t y ( P )
a n d ove r f l ow
a f f ec t t h i s f l a g w i t h
ope r a t i o n s a f f e c t t h i s
P / V
ho l d s p a r i t y ,
I f
P / V
e v e n ,
=
1 i f t h e r e s u l t o f the
=
1 i f or s u b t r a c t ope ra t i on p ro d uc e d
t h e a dd
4
t he a ccumu l a t o r .
b i t o f
=
1 i f
the p re v i o u s o p e r a t i on
co n j unc t i on w i t h the
t h e re s u l t i n to packe d
c o r r e c t
1 i f the ope r a t i o n p roduc e d a carry f rom
0 .
( V ) sha r e the
the p a r i ty
f l a g w i t h
P / V
=
0 i o dd .
f r e s u l t i s
op e ra t i on
was a
dec i ma l a d j u s t
1 i f t he
I f