Commodore Amiga A500 Technical Reference Manual page 219

The
8520
Chip
USS
PAO
PA
l
PA2
PA3
PA4
PA5
PA6
PA7
PBO
PB 1
PB2
PB3
PB4
PB5
PB6
PB7
PC
TOD
VCC
CNT
SP
RSO
1
RSl
RS2
RS3
RES
DBO
DB
l
DB2
DB3
DB4
DB5
DB6
DB7
02
FLAG
CS
R/ W
IRO
Figure
6.5. 8520
Pin Configuration