Ibm Personal Computer At Serial/Parallel Adapter; Serial Portion Of The Adapter - IBM RT Series Hardware Reference Manual

IBM Personal Computer AT
Serial/Parallel Adapter
The IBM Personal Computer AT Serial/Parallel Adapter provides
a parallel port and a serial port. It plugs into a system-board
expansion slot. All system-control signals and voltage
requirements are provided through a 2- by 31-position card edge
connector.
Serial Portion of the Adapter
The serial portion of the adapter is fully programmable and
supports asynchronous communications. It will add and remove
start, stop, and parity bits. A programmable baud-rate generator
allows operation from 50 baud to 9600 baud. Five-, six-, seven-
and eight-bit characters with 1, 1.5, or 2 stop bits are supported.
A prioritized interrupt system controls transmit, receive, error,
and line status as well as data-set interrupts.
The rear of the adapter has a 9-pin D-shell connector that is
classified as an RS-232C port. When the optional IBM
Communications Cable (9-Pin), which has a 9-pin D-shell
connector on one end and a 25-pin D-shell connector on the
other end, is connected to the adapter, the 25-pin end of the cable
has all the signals of a standard EIA RS-232C interface.
The following figure is a block diagram of the serial portion of the
adapter.
Serial/ParaDel Adapter 1