ACT apricot - RS232 C Connector Detail

SERIAL INTERFACE
the correct baud rate. Three of the values detailed in the
TIMER chapter produce a baud rate value which is
marginally outside the +/- 5% tolerance normally allowed
for communications over an RS232C link. These values,
3600, 7200 and 19200 bauds should therefore be used only
for Apricot-to-Apricot communications.
The selected transmit rate clock (TxCA) is also supplied
to the RS232C connector (connector pin, Tx clock), for use
by the external data communications equipment.
Five of the most commonly used RS232C modem control
lines are connected to various inputs and outputs of channel
A of the SIO/available for coordinating data transfers over
the serial link. These include the outputs RTS and DTR,
and the inputs DSR, CTS and DCD. Use of each individual
modem control line is dependent on compatible facilities
within the external equipment. Generation of the output
modem control lines and status monitoring of the input
modem control lines is directly under program control. The
SIO can be programmed to generate an interrupt to the CPU
every time a transition occurs on any of the input control
lines. DSR is not available in synchronous modes.
RS232C Connector Detail
The definition of the available RS232C connections
provided by the 25-way D-type connector are detailed in the
following table. The RS232C voltage levels are defined
below.
The line idle condition is indicated by continuous
marking.
1. Line marking; Between -3V and -15V relative to OV.
2. Line spacing; Between +3V and + 15Vtelative to OV.