Spectravideo SVI 318 Service – Technical Manual page 121

Dat a O rg an i z a t i o n on t h e D i s c Me d i a
The d i s c ca r t r i dge con t a i n s a ma gne t i c ox i d e - co a t e d d i s c , wh ich i s
t h r o u gh a c ce s s ho l e s i n t h e p l a s t i c j acket .
D r i ve , r e c o r d s d a t a on t h e d i s c at a d d r e s s e d l o c a t i on s .
dat a o n t h e d i s c , t h e r e a d /wr i t e he a d qu i c k l y l o ca t e s a n d re t r i e ve s the de s i re d
da t a . A s t he d i sc s p i n s , s e r i a l b i na ry d a t a i s r e c o r d e d ( o r rea d ) on
co nc e n t r i c c i r c l e s ca l l e d t r ac k s .
e dg e o f t h e d i sc ; t h e i n ne rmos t t r ack i s t r ack
d i v i d e d i n t o se c t o r s , wh i c h a r e ma rke d by o n e ho l e punche d i n the d i s c .
a dd i t i o na l ho l e , INDE X , oc c u rs ap p ro x ima t e l y 1 8 0 degre e s be fore sec t o r 0
( s e c t o r l o c a t i o n depe n d s up on the re l a t ive po s i t ion of the re a d /wr i t e he a d and
t he i nd e x s e n s o r ) .
wh i l e e a ch s e c t o r s t a r t s b y a pu l s e in i t i a t e d b y a se c t o r h o l e .
t he phy s i c a l l en g t h o f s e c t o r s va r i e s d i re c t l y in p r op o r t i on t o the d i s t ance o f
th e t r ack f rom t h e ce n t e r o f t h e d i s c , d a t a b i t s a r e c l o s e r t o g e t h e r o n the
h i gh e r numb e re d t r ack s .
D oub l e D e n s i t y
Dou b l e capac i t y can be ob t a i ne d
me t h o d o f � n c o d ing d a t a on t he d i sc .
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