The board had two serial I/O ports connected to programmable UARTS. It
had 1 parallel I/O port that was typically used for printer I/O. Of
the two serial ports, for one the signals could be either TTL or RS232
levels. The other could be RS232 or a special interface for cassette
tape storage. UART baud rates were 75-9600, slow even for that time.
Very useful however, there was circuitry for an audio cassette interface to
read and record in the then popular "Kansas City Standard" format.
This BTW, ran at 1200 baud allowing the storage of about 180K on a 30 minute
cassete.
The manual for this board can be obtained
here.
