Spectravideo SVI 318 Service – Technical Manual page 83

The P ro grammab l e Soun d Gene r a t o r
The P S G AY-3 -8 1 90 gene r a t e s a l l re qu i re d s o u n d un d e r s o f tware con t ro l .
a re t w o 8-b i t I / 0 p o r t s wh i ch a re p ro g r amme d a s fo l l ow :
Prog ramm e d a s i n p u t po r t and i s u s e d f o r the i np u t s i gna l f rom two
Po r t A
j oy s t i c k s c o n t r o l l e r s .
Po r t B P r o g ramm e d a s ou t p u t po r t wh i c h i s us e d t o ou t p u t the bank con t r o l
s i g na l s f o r t he memory c h i p s .
D e t a i l s i g na l s f o r t h e p o r t s a re l i s t e d in t h e t ab l e be l ow :
AY- 3 -8 1 90 I / 0 P o r t A
DO
J oy s t ick
D 1 - -
do
-
- -
D 2 ---- do
-
D3
-- do
-
--
D4 J oy s t ick
D S
- - - do
- -
D 6
- - do
- -
D 7 -
do
- -- -
AY-3-8 9 1 0 I / 0 P o r t B
DO
B ank 1 ( G ame
D 1
Bank 2 1
D 2
B ank 2 2
D3
Bank 3 1
D4
B ank 3 2
D 5
Cap Lamp ( Ke y bo a r d C a p Loc k )
D 6
ROM 2 e n ab l e
D 7
ROM 3 enab l e
1 No Co n t a c t
=
1 0
F o rw a r d
=
0 Backwa r d
=
0
Le f t
0 R ig h t
=
2 0
Forw a r d
=
0 Backwa r d
=
0 L e f t
0 R i gh t
=
Ca r t r idge )
=
1 D i s ab l e ; 0
=
1
D i s ab l e ; 0
4 . 50
E nab l e )
=
Enab l e )
=
The r e
0 BANK ON
=
1 BANK OFF
=