Pattern Definition Registers
84 – CIO Chip
VL-486-4 Reference Manual
Table 59: Pattern Specification Definition
Mask
Register
Transition
Register
Polarity
Register
Pattern
Specification
0
0
0
Bit Masked Off (X)
0
1
0
Any Transition (
!
or
"
)
1
0
0
Zero (0)
1
0
1
One (1)
1
1
0
One to Zero Transition (
"
)
1
1
1
Zero to One Transition (
!
)
If the pattern match mode is OR-Priority Encoded Vector, the transition detection patterns
should not be specified (PTn should be set to 0). If the AND mode is specified, no more than one
bit should be specified to detect transitions.
P
ORT
A
AND
B D
ATA
R
EGISTERS
CIOPORTA (READ/WRITE) 0DH (also directly accessible at I/O Port 00E5h)
CIOPORTB (READ/WRITE) 0EH (also directly accessible at I/O Port 00E6h)
D7
D6
D5
D4
D3
D2
D1
D0
D7
D6
D5
D4
D3
D2
D1
D0
Ports A and B each have a data path that is composed of three registers: an Input Data register,
an Output Data register, and a Buffer register. Output data written to the data register is stored in
the Output Data register. Reading the data register returns the contents of the Input Data register.
The buffer register is used to buffer the input and output data if the port is configured as a port
with handshake. If so enabled, it is used by the bit port to latch data when a pattern match is
detected.
The individual bits of the port data registers map directly onto the port I/O pins (bit 0 of the Port
A Data register corresponds to the PA0 pin, etc.).