Teac MV1421, Service Manual

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6. IC DESCRIPTION
6-1. SDA5255 ( Micro controller & Teletext Decoder )
1. General description
T h e T D A 5 2 5 5 c o n ta in s a s lice r fo r V P S a n d T T X , a n a cc e le ratin g a c q u is itio n h a rd w a re m o d u le ,
a d isp la y g e n e ra to r fo r "L E V E L 1 "T T X d a ta a n d a 8 b it u -c o n tro lle r ru n n in g a t 3 3 3 n se c c y cle tim e .
T h e co n tro lle r w ith d ed ica te d h a rdw a re g u a ra n te e s fle xib ility, d o e s m o s t of th e in te rn a l p ro ce s sin g o f T T X
a c q u isitio n , tra n s fe rs d a ta to /fro m th e e x te rn a l m e m o ry in te rfa c e a n d re c e iv e s/tra n sm its d a ta v ia IIC an d
U A R T u s e r in te rfa ce s .
T h e S lice r c o m b in e d w ith d e d ic a te d h a rd w a re s to re s T T X d a ta in a V B I 1 K b y te b u ffe r.
T h e u -c o n tro lle r firm w a re d o e s th e to tal a c q u isitio n ta sk (h a m m in g a n d p arity ch e c k s, p a g e s e a rch a nd
e v a lu a tio n o f he a d e r c o n tro l b its ) o n c e p e r fie ld .
2. Feature
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A c q u is itio n :
- fe a tu re s e le c tio n v ia sp e c ia l fu n ctio n re g is te r
- s im ulta n e o u s re ce p tio n o f T T X a n d V P S
- F ixe d fra m in g co d e fo r T T X an d V P S
- P ro g ra m m a b le fram in g c o d e w in d o w fo r T T X
- A c qu isitio n d u rin g V B I
- D ire c t ac c e ss to V B I R A M b u ffe r
- A c qu isitio n o f p a c ke ts x2 6 ,x2 7 ,8 /3 0 (firm w a re )
- A s sis ta n c e o f a ll re le va n t c h e ck s (firm w a re )
- 1 -b it fra m in g -c o d e e rro r to re la n ce (sw itch a b le )
•
Display
- F e atu re s e le cta b le v ia s p e cia l fu nc tio n re g iste r
- 5 0 /6 0 H z d isp la y
- L e v e l 1 se ria l a ttrib ute d is p la y p a g e s
- b lan k in g a n d co n tra s t re d uc tio n o u tp u t
- 8 d ire ct a d d re ss a b le d is p la y p a g e s
- 1 2 x 1 0 c h a ra c te r m a trix
- 9 6 ch a ra c te r R O M (sta nd a rd 9 0 ch a ra c te r s e t)
- 1 4 3 n a tio n a l o ptio n c h a ra cte rs fo r 11 la n g u a g e s
- 2 8 8 ch a ra cte rs fo r x 2 6 d is p la y
- 6 4 b lo ck m o sa ic gra p h ic c h a ra c te rs
- 3 2 fre e a d d re ss a b le c h a ra cte rs fo r O S D in e x p a n d e d c h ara c te r R O M + 3 2 in sid e O S D b o x
- d o u b le h e ig h t (T O P /B O T TO M )
- c o n c ea l/re ve a l
- tra ns p a re n t fo re gro u n d /b a c k gro u n d ins id e /o uts id e o f a b o x
- c u rso r (c o lo u r c h an g e s from fo re g ro u n d to b a c kg ro u n d c o lo u r)
- fla s h (fla s h ra te 1 s)
- p ro g ra m m a b le h o riz o n ta l a n d v e rtic a l s y n c d ela y
- h a rd w a re a ss is te d fa s t d isp la y p a g e era s e
- fu ll sc ree n b a ck g ro un d co lou r in o u te r sc ree n