Bally 5000 Plus, Manual

Page: 75 / 388

3 . MPU BOARD
C i r cu i t Descr i p t i on ( cont ' d )
S a f e RAM
U 1 0 decodes t h e a d d r e s s and
sends SRCS s i gna l f r om p i n 21 t o
S a f e RAMs ( U 3 1 p i n 2 0 and U 1 00
p i n 20 s i mu l t a neous l y ) .
E P ROM
U 1 0 decodes t he a d d r e s s and
sends ROMCS 1 s i gna l f r om p i n 1 6
t o t he E P ROMs ( U 1 2 p i n 20 and
U 1 5 p i n 2 0 ) .
U 1 0 decodes t h e add r e s s a n d
ROMCS2 s i gna l f r om p i n 1 7
E P ROMs ( U 1 8 p i n 20 and
20) .
sends
t o t he
U20 p i n
RAM
U 1 0 decodes t he a d d r e s s and
sends RAMCS s i gna l f r om p i n 1 8
to t h e memo r y decode r ( U8 p i n
& 1 5 s i mu l t a neous l y ) .
U8 decodes t h e s i g na l and sends
RAM 1 C 1 f r om p i n 1 2 t o J 7 . See
J UM P E R S E L ECT TAB L E I n t h i s
S e c t i on .
F r om J 7 t he RAM 1 CS s i gna l goe s
to t h e RAMs ( U 1 3/ U 1 4 p i n 20 and
U 1 6/ U 1 7 p i n 20 ) .
6800 c h i ps
U 1 0 decodes t h e a d d r e s s and
sen d s a I
0
c a I I lO s i g n a I f r om
p i n 1 9 to t h e a d d r e s s decoder
( U7 p i n 1 8 ) . U7 decodes wh I ch
c h i p se l ec t s i g na l t o send .
3-1 8
r e a l t i me c l oc k
U7 p i n 3 sends RTC t o t h e r e a l
t i me c l oc k c i r cu i t ( U 30 ) .
NOT E S