Bally 5000 Plus, Manual

Page: 96 / 388

C i rcu i t Descr i pt i on ( cont ' d )
The OEl s i gn a l beg i ns w i t h U 1 p i n 8
send i ng
t he
l O S
t o U 1 1 p i n 5 . U 1
p i n 9 sends t he R /W s i gn a l
t o be
buf f e r e d I n U48 . U48 p i n 1 8 sends
R/W t o U42 . U 4 2 p i n 8 sends t he
I nve r t ed R/W ( R EAD ) s i gna l t o U 1 1
p i n 4 . The l O S a n d R EAD s i gn a l s
a r e g a t e d t h r oug h U 1 1 .
U 1 1 p i n 6 sends OEl t o U 1 2 p i n 2 2
a n d U 1 8 p i n 2 2 .
Read upper da t a b y t es
To read f r om t he uppe r d a t a
over t he upper d a t a l i ne s
0 1 5 ) , U 1 5 f rom t he pa i r , U 1 2
and U20 f r om t he pa i r , U 1 8 &
need ( 1 ) a n even a d d r e s s ( 2 )
se l ec t s i gn a l
a n d ( 3 ) a n
enab l e h i gh ( OEH ) s i gna l .
b y t es
( 08-
& U 1 5 ,
U 2 0 ,
a c h i p
out pu t
T h e O E H s i gna l beg i ns w i t h U 1 p i n 7
send i ng t he UDS t o U 1 1 p i n 2 . U 1
p i n 9 sends t he R /W s i gn a l t o be
buf f e r e d I n U48 .
U48 p i n 1 8 sends
R/W t o U 4 2 . U 4 2 p i n 8 sends t he
I nve r t ed R /W ( R EAD ) s i g na l t o U 1 1
p i n 1 . The UDS and R EAD s i gna l s a r e
g a t e d t h rough U 1 1 .
U 1 1 p i n 3 sends O E H t o U 1 5 p i n 2 2
and U20 p i n 2 2 .
Read d a t a wo r d s
U 1 2 & U 1 5 ope r a t e a s a p a i r a n d U 1 8
& U20 ope r a t e 'a s a p a i r .
To r e ad
d a t a wor ds ove r t he d a t a l i nes ( 00-
0 1 5 ) ,
e a c h p a i r needs ( 1 ) even
addr esses ( 2 ) c h i p se l ec t s i gn a l s
and ( 3 ) t he O E H a n d
O E l s i gn a l s
s i mu l t a neous l y .
3 . MPU BOARD
NOT ES
3-39