Spectravideo SVI 318 Service – Technical Manual page 126

2 2 TES T
2 3 HEAD LOAD T IM I NG
2 5 READ GATE
( 1 79 1 / 3 )
2 5
S I DE SELECT
OUTPUT ( 1 7 9 5 ,
1 7 9 7 )
26 READ CLOCK
27
RAW READ
LOAD
28 HEAD
29 TRACK GREATER
THAN
43
T h i. s
p .Yc c s
TEST
i Tl p u t i s
o r
o n ly
l e f t
f" ,· :: f -1. :;
. .
a
HLT Whe n
i n p u t
e n g a g e d .
the head is n s s ume d to
RG A h i gh l e ve l on th i s ou t pu t i n d
t o t h e d a t a s e p a r a t o r c i r c u i t ry tha :
a f i e l d of z e ro s ( o r o n e s ) h a s
enc o u n t e re d , a n d i s u s e d fo r
s y n c h r o n i c z a t f on .
s so
T he l o g i c l e ve l o f t he S i d e S e l < c t
' S '
Ou t p u t i s d i r e c t l y c on t r o l l e d b)
e n
f l ag i n Type I I o r
S -
W h
The
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S
d
S i d e S e l ec t O u tp u t i s on l y
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o
l g 0 up on
o i
RCLK A nom i n a l s qu a r e-wave c l ock s i gn
d e r i v e d f rom t h e d a t a s t r e am
p ro v i d e d to t h i s i n pu t .
( i . e . R CLK t r a n s i t i o n s ) r e l a t i ve t o
RAW READ
( RCLK h igh o r l ow ) i s no t .
RAW READ
The d a t a inp u t
t he d r i ve .
negat i ve p
f l ux t r a n s i t i on .
HLD
HLD ou tp u t
The
t h e Rea d-Wr i t e h e a d
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ET
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44- 7 6 .
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