Bally 5000 Plus, Manual

Page: 171 / 388

4 .
I /O BOARD
Theory of Oper a t i on
The I /O boa r d I n t e r f aces t he M P U boa r d w i t h ( 1 ) t he e x t e r na l I /O o f t he r ee l
mechan i sm boa r d , doo r d i s t r i bu t i on boa r d , a n d P i C K 3 boa r d a n d ( 2 ) e x t e r na l
sw i t ches , l i g h t i ng , progress i ve s , so l eno i ds , a n d me t e r s t h r ough t he b a c K p l a ne .
The I /O boa r d can a d d r e s s 1 6 b y t es o f p a r a l l e i por t s w i t h i n t he 4K b y t es o f MPU
boa r d memor y space a l l oc a t ed for t he I /O boa r d .
A po r t I s a c h i p t h a t can
t r an s f e r 8 b i t s ( 1 b y t e ) of d a t a . T h e por t s of t he I /O boa r d a r e ou t pu t , i nput ,
and b l -d l r e c t l on a l .
T h e
I /O boa r d h a s a 1 6 b i t d a t a b u s f o r t r an s f e r r i ng d a t a b y t es o r
T h e I /O boa r d h a n d l es d a t a e x c h a nges s i m i l a r t o t he memo r y c h i ps
boa r d . See
�
MPU BOARD unde r 68000 M i c r op rocessor t o r ev i ew
( as y nc h r onous ) , a d d r e s s bus , d a t a bus , b y t e , a n d wo r d .
da t a wo r ds .
on
t he MPU
68000 c h i p
The decod i ng o f t he por t s a n d 2 3 a d d r es s l i nes i s e x p l a i ne d unde r C i r cu i t
Descr i pt i on I n t h i s Sect i on . T h e r ee l mechan i sm a n d P i CK 3 por t s a r e no t on t he
I /O boa r d , but t he d a t a I s bu f f e r ed t h r ough t he I /O boa r d .
T h e a c t i ve LOW d a t a s t r obe ( DSO) s i g na l o r i g i na t e s on t he MPU boa r d a s t he LOS ;
t he a c t i ve H I GH DSO a s t he UDS . The a c t i ve LOW wr i t e ( WR I T E ) s i gna l o r i g i na t es
on t he MPU boa r d a s t he R /W s i gna l . T h e a c t i ve H I GH WR I T E s i gna l o r i g i na t e s on
t he MPU boa r d a s t h e r e a d of t he R /W .
FROM
M P U
D E C O D E
LOGIC
1 /0 BLOCK D I AGRAM
I N P U T
PORTS
1
-
5
CON TROL
DO
-
0 15
F i g . 4 - 1
O U T P U T
P O R T S
1
-
6
R E E L
M EC H A N I S M
P O R T S 6 - 1 1 ( 8 )
P I C K �
P O R T 1 3 ( 0 )
4-3