W65C21S Datasheet, PDF (9/16 Pages) List of Unclassifed Manufacturers – Peripheral Interface Adapter (PIA)

The Western Design Center, Inc.
CA1,CA2
CB1,CB2
IRQAB, IRQBB
PWI
tRS3
Figure 7. Interrupt Timing
W65C21S Data Sheet
PHI2
tIR
IRQAB, IRQBB
Figure 8. Interrupt Clear Timing
Table 1. Control Registers
REGISTER
SELECT PIN
RS1 RS0
0
0
0
0
0
1
1
0
1
0
1
1
DATA
DIRECTION
REGISTER
ACCESS
CONTROL BIT
CRA-2 CRB-2
1
-
0
-
-
-
-
1
-
0
-
-
REGISTER SELECTED
Peripheral Interface A
Data Direction Register A
Control Register A
Peripheral Interface B
Data Direction Register B
Control Register B
Table 2 Register Addressing
DDR
DATA
P
P
PIN
N
INPUT
Figure 9 Port A, CA2 Buffers
DDR
P
PIN
DATA
INPUT
(OUTPUT MODE)
N
INPUT
(INPUT MODE)
Figure 10 Port B, CB2 Buffers
The Western Design Center
W65C21S
9