ACT apricot - Page 176

SERIAL INTERFACE
SYNCA Synchronization. Control input from the
RS232C interface via a line driver. When used
with a modem, the active state (logic low)
indicates that the modem is ready to start
handling data. This input is only available in
the asynchronous mode. SYNCA sets an
associated control bit within an internal
register according to the state of SYNCA, and
also has the facility to generate an interrupt
request to the Interrupt Controller, every time
a transition occurs on SYNCA.
RTSA Request to send. Control output to the RS232C
interface via a
line driver. When used with a
modem, the active state (logic low) indicates
that the SIO has data ready to send. R TSA is
controlled by software, following the logic state
of an associated control bit within an internal
register.
CTSA Clear to send. Control input from the RS232C
interface via a
line receiver. When used with a
modem, the active state (logic low) indicates
that the modem is ready to receive data. CTSA
can be programmed to operate in one of two
modes. The first mode allows CTSA to act as
the enable control line to the transmit section
of channel A. The second mode sets an
associated control bit within an internal
register according to the state of CTSA and also
has the facility to generate an interrupt request
to the Interrupt Controller, every time a
transition occurs on CTSA.
W/RDYA Wait/Ready A. Control output to theDMA
request line of the Input Output Processor (lOP
DRQ2). When active (logic low), indicates to
the lOP that the SIO is ready for aDMA
transfer operation to/from the SIO.