Port A
Port A is an 8 way open collector chip uln2803 . This is a very popular chip and I use a similar one on my I/o board (uln2804).
More information at link below.
http://www.onsemi.com/pub/Collateral/ULN2803-D.PDF

Port B
Port B is an 1489 quad rs232 line driver (2 off). The beauty of this chip is that it converts rs232 voltages +12v ..-12v to ttl 5v.
http://www.angelfire.com/fl3/technicothica/ttlrs232.html

Port C
Port C is an Pcf 8574 i2c to 8 bit port . The eight pins can be programmed as either 8 in or 8 out . I2c is a philips two wire protocol. You can connect up to 8 of these chips on the same bus. More information at link below.
http://www-s.ti.com/sc/psheets/scps068/scps068.pdf