Bally 5000 Plus, Manual

Page: 78 / 388

C i r cu i t Desc r i p t i on ( co n t ' d )
U 1 0 1 uses t he p e r I p h e r a I I n t e r r up t
s i gna l , l ACK , a n d t h e add r e s s
s i gna l t o de t e r m i ne whe t he r t h e
c h i p i s a 6800 o r a 68000 .
6800 : U 1 0 1 sends a VPA to t h e 68000
m i c r o p r ocessor wh i c h sees an
auto v e c t o r numbe r and t he
co r r e spond i ng I ns t r uc t i on
p rocess beg i ns .
68000 : U 1 0 1 sends a ve r i f i ed l ACK
s i gna l to t he c h i p . The c h i p
sends I t s u s e r v e c t o r numbe r
by t he d a t a bus l i ne s ( 00-0 7 )
t o t he m i c r o p r oc e s so r .
The c h i p sends a OTACK
to U35 p i n 7 . U35
sends O TACK to t he
m i c r o p rocessor ( U 1 p i n
s i gna l
p i n 9
68000
1 0 ) .
AC f a l
I
and l ow vo l t age a r e a l e ve l
7 I n t e r r u p t . Leve l 7 I s t he
h i g h e s t p r i o r i t y I n t e r r u p t .
3 .
MPU
BOARD
NOT E S
3 - 2 1