Spectravideo MKI, Сервисное – Техническое руководство, Страница: 76 / 134

TM S - 99 2 9 V i d eo Proce s so r
Th i s P re l im ina ry Spec i f i c a t i o n o f the Til S - 99 2 9 i s to b e con s i d e re d as a n "ADD
ON "
to the ba s i c TMS-99 1 8 spec i f i c a t i o n . The TilS-99 2 9 i s e f f ec t i v e l y ident i c a l
to t h e TMS-99 18 func t i ona l l y a n d on l y has t h e co l ou r v i d e o s e c t i o n tha t i s
d i f f e re n t .
The TM S - 99 1 8 p ro v i d e s a compo s i t e co l o u r v i d e o s i g na l ou t p u t tha t i f dr iven by
a s u i t a b l e amp l i f i e r ca n go d i r ec t l y i n t o any co l o u r v i d e o mon i t o r . The . co l our
bu r s t f re que nc y i s the
VDP
o s c i l l a tor i np u t f re q uency d i vided by th ree .
Ex te rn a l v i d eo m i x ing w i t h an e x t e rna l re f e rence sou rce can a l s o be ach i ev e d by
i n pu t t ing t h i s e x t e rna l s ou rce d i re c t ly i n t o the TMS-99 1 8 .
I n t h e TMS-9929 the co l ou r and luminanc e / s ync in f orma t i o n i s p rov i d e d on thre e
p i ns r a t h e r than a s ing l e p in i n t he f o rm of two c o l ou r d i f f e re nce s ig n a l s and,
one l um i nance s i g na l w i t h a l l the ve rt i c a l and hor i z ont a l t i ming inc l uded .
So
we h a ve R-Y , B-Y , and Y r e s p e c t i ve l y . The two c o l ou r d i f f e re nce s igna l s are
us e d then by an exte rna l quadra t u re modu l � t o r video enc ode r . It i s ou t s i d e the
V id eo D i sp lay P roce s s or that t he compo s i te c o l ou r v i d eo s i g n a l is g e u e r a t e d
i n t o a PAL or Secam compa t i b l e
TV
s i gna l . The exte rna l v i d e o m ix i ng i s a l s o
done o u t s ide a n d i t i s the THS-9929 t o d e c i de wh en th i s mode i s e n t e re d . Th i s
i s ach i e ve d by a spec ia l l eve l d i s t i nc t i on ma de by the R-Y and B-Y VDP outpu t s .
When e x t e rn a l v id e o i s e n t e re d the se two ou t puts g o t o the e qu i va l ent o f the
s ync pe rce ntage l eve l o f the b lack-wh i t e swing in the luminance ou tpu t , i . e .
t he c o l our d i f f e rence outpu t s a re norma l ly sw ing ing between t he l um i nance
b l a cm-wh i t e vo l t age l eve l s and it is on ly in the e x t e r n a l video mode tha t the se
ou t p u t s g o to t he re se rve d " s ync" leve l .
P ha s e locking of the VDP to the e x t e r na l
PAL
burst f re quency i s de s i rab l e i f
i n t e r -hum o r c rawl e f f e c t s want t o be m i nim i z e d . The TMS-9 9 2 9 o sc i l la tor c lock
mus t s t i l l , howeve r , be ma i n t a i ne d w i t h i n i t s p re s c r i be d l i m i t s of osc i l lator
ope r a t i on . CPUCLK si gna l is no l onger ava i l ab l e i n the Eu rope an TMS-9929 .
The P ro g rammab l e Sound Gene r a t or ( PSG) i s eas i l y in t e r face d to any b us
o r i e n te d s y s tem. I t s f l ex i b i l i t y makes i t use f u l in a pp l i ca t i ons s uch as mu s ic
s ynt he s i s , sound e f f e c t s genera t i o n , aud i b l e a l a rms , tone s ig na l l ing and FSK
modems . The ana log sound outputs can e ach p rovide 4 b i ts of log a r i thm i c
d i g i t a l to analog sound conve r s ion , g re a t l y enhanc i ng t h e dynam ic range o f the
sound s p roduce d .
In order t o per fo rm sound e ff ec t s wh i l e a l l ow ing the p roc e s s o r t o con t i nu e i ts
o t h e r t ask s , t he PSG can con t i nue to produce s ound a f ter the i n i t ial command s
ha ve be e n g iven by the contro l p roce s s o r . The fac t tha t rea l i s t ic sou n d
p roduc t i on of t en invo lves �ore t h a n one e f fect i s s a t i s f ie d by the three
independen t l y co n t ro l lab l e cha nne l s ava i la b l e in the PSG .
4 . 43