CABLE CONNECTION REFERENCE GUIDE
A typical computer, as seen from the back.
The parallel port on a PC is always 25-pin female.
Serial ports on a PC are always male, and have 9 or 25 pins. Though the pinouts of the serial port on a PC are always the same, the pinouts for the serial port on a printer are not always predictable. Many times, a "null modem" cable is all that's needed.
USB is faster than serial or standard parallel communications.