Master Control Registers
76 – CIO Chip
VL-486-4 Reference Manual
M
ASTER
C
ONFIGURATION
C
ONTROL
R
EGISTER
CIOMCC (READ/WRITE) 01H
D7
D6
D5
D4
D3
D2
D1
D0
PBE
CT1E
CT2E
PCECT3E
PLC
PAE
LC1
LC0
The Master Configuration Control register contains the control bits used to enable different
sections of the device after they are initially configured, as well as the bits used to link the ports
together and the timers together. All bits are cleared to 0 by resetting the device. The register is
read/write.
Table 52: Master Configuration Control Register Bit Assignments
Bit
Mnemonic
Description
D7
PBE
Port B Enable — This bit allows Port B to be configured initially without
setting its IP erroneously or having its I/O lines go low-impedance until it is
safe to do so.
PBE = 0
Inhibits the Port B logic from issuing an interrupt request (its
IP cannot be set); however, if IP was already set, clearing
PBE inhibits READY/WAIT assertion, holds all1's catchers
in a transparent condition, and forces the Port B I/O lines
into a high-impedance state.
PBE = 1
Allows Port B to operate normally
D6
CT1E
Counter/Timer 1 Enable — Controls counter/timer 1.
CT1E = 0
Counter/Timer 1 is put into an initialized state: its IP cannot
be set (however, if IP was already set, clearing CT1E does
not clear IP), the Count In Progress (CIP) flag is cleared,
Read Counter Control (RCC) is forced to 0, and all trigger
inputs are ignored.
CT1E = 1
Counter/timer 1 functions normally.
D5
CT2E
Counter/Timer 2 Enable — Controls counter/timer 2.
CT2E = 0
Counter/Timer 2 is put into an initialized state: its IP cannot
be set (however, if IP was already set, clearing CT1E does
not clear IP), the Count In Progress (CIP) flag is cleared,
Read Counter Control (RCC) is forced to 0, and all trigger
inputs are ignored.
CT2E = 1
Counter/timer 2 functions normally.