Spectravideo SVI 318 Service – Technical Manual page 10

*
SVI-318/SVI-328
NAME :
CNTR L 2
2
+ 1 2V
3
- 1 2V
4
5 CNTRLl
6
WA IT
1
RST
8
CPUCLK
9- 24 A15-AO
25 RFSH
n
d hark
a
II EXPANDER BUS SIGNAL DESCRITPION
I / 0 : DESC RI PTION :
0 + 5V powe r supp l y .
a l l p e r iphe r a l c a rd s.
I S p e c t rav i d e o game a d a p tor fo r co l e co g am es CONTROL
s i g na l ( norma l l y he l d H IGH by a 3 . 3 K o hm re s i s t or ) ,
Th i s s i gna l , when t h e game adap t o r i s i n u s e ,
c on t ro l s t he da ta tr an s f e r be twe en th e CPU and the
a d a p t o r du r i ng
+1 2 V power supp ly .
0
a l l p e r iphe r a l card s .
0 -1 2V pow e r s up p l y .
pe r i p he ra l c a r d s .
I
S p e c t r av i d eo game a da p to r f o r co l e c o
CONTROL s i gna l ( n o rma l ly h e l d HIGH by lK ohm
re s i s t o r ) .
Wh e n t he a d a p t o r i s i n u se ) , d i sab l e s a l l i n t e rna l
( i . e . SVI-3 1 8 / SVI-3 2 8 and M a rk II ) I / 0 a d d re s s
d e c o d ing , and inv e r s es A1 5 .
I In d i c a t e s to Z80A CPU tha t the a d d re s s e d memo ry
or I / O dev i c e s a re no t ready for da ta t rans f e r .
I Whe n th i s s i gna l i s pu l l e d LOW the C PU be g i ns a
RESET c y c l e.
and d a t a bus ent e r a high impe ndance s t a t e and the
co n t r o l s i gna l s e n t e r th e i nac t ive s t a t e .
0
Bu f f e r e d s y s tem c loc k of f requency 3 .58MHz .
Bu f f e re d ADDRESS BU S .
p rov i d i ng a dd r e s ses for memo r y d a t a exc hange
I / 0 dev ice da ta exc hange .
0
Bu f f e r e d REFRESH s i gna l fo r the dynam ic
expand e rs on ly .
7
l ower b i t s of the ad d res s bus c on t a i n a ref re s h
a dd re s s for the dynam ic RAM.
2.5
300mA cur r e n t i s av a i l a b l e f o r
the
ex t e r na l I / O a d d re s sing .
Max imum c u r r e n t i s lOOmA fo r
Maximum c u r rent i s SOmA for a l l
This s i gna l , wh en pu l l e d LOW ( i. e .
Du r ing t h i s RESET c yc l e, the a d d r e ss
Th is i s a 1 6 -b i t a dd res s
This
s i gna l i n d ic a t es that the
*
game s
bus
and
RAM