Introduction to the Parallel Port

• It's that D-shaped port on the back of your computer with 25 pins (the one you plug your non-usb printer into)
• It has 8 Data Bits in the Data Register (D0 to D7)
• This means you have 8 wires you can set / get the value of, and there are only two valid settings: 1 and 0
• 1 means the bit is "on" and sinking 5V, 0 means it is "off" and doing nothing - pretty simple
• It also has 8 ground pins (in white)