Bally 5000 Plus, Manual

Page: 163 / 388

C i r cu i t Descr i pt i on
ROM Boa r d
The P i ggyback ROM Boa r d s i t s on t op o f t he
MPU boa r d and conne c t s t o I t t h r ough
t wo
28-p l n soc ke t s a t l oca t i on s U 1 8 and U 2 0 .
T h e P i ggyback ROM Boa r d a l l ows sof t wa r e t o
b e e x panded . T h e ma i n p r og r ams w i I I be on
t he MPU boa r d a t l oca t i on s U 1 2 and U 1 5 . On
t he P i ggyback ROM Boa r d a r e t he p e r sona l i t y
EPROMs and supp l eme n t E P ROMS wh i ch con t ro l
pe r sona l i t y f e a t ur e s and g ame con t r o l . An
8-pos l t l on
s hun t w i t h b r eakaway J umpe r s ,
wh i ch con t ro l s pe r ce n t age , I s l oc a t e d a t
SW2 .
These p a r t s a r e enab l ed and cont r o l l ed f r om
t he P i ggyback PAL Boa r d . T h e boa r d s I n t e r ­
f ace t o each o t h e r t h r ough a 4-c l r cu l t f l a t
r i bbon c a b l e . When a n a c t i ve l ow s i gn a l
I s
p r esen t a t t he enab l e p i ns o f t he E PROMs
( p i n 2 0 ) t oge t he r w i t h an a c t i ve l ow s i gn a l
a t e i t he r O E L ( U 1 8 and U 3 , p i n 2 2 ) o r OEH
( U20 and U 4 , p i n 2 2 ) , a n a d d r e s s p r es e n t a t
t he E PROM w i I I cause d a t a t o be ou t pu t on
t he l owe r da t a bus 0 0-07 and upper d a t a bus
08-0 1 5 .
The J umper s h un t s a r e enab l ed when a n
a c t i ve l ow s i gn a l I s p r esen t a t p i ns 1 and
1 9 at U6 , wh i ch w i I I cause t he J umpe r s to
be r ea d and da t a t o be t r an s f e r r e d ove r t he
upper da t a bus 08-0 1 5 .
PAL Boa r d
The P i ggyback PAL Boa r d , wh i c h r e p l aces t he
PAL c h i p p re v i ous l y used a t U 1 0 , p l ug s I n to
l oca t on U 1 0 on t he M P U boa r d . Th i s boa r d
con t an s a decode r PAL t h a t decodes spec i ­
f i ed
add r e s s l oc a t i on s for MPU se l e c t i ons
of ROM , RAM , I /O , and t he J umper shun t s . An
a c t i ve
l ow on one o f t hese ou t pu t s w i I I
enab l e t he spec i f i ed dev i ce .
FO-5000- 1 ( Re v A )
3-A . Memor y Boa rds
NOTES
3A-3