Parallel Interfaces
There are 3 main parallel interfaces. The 25 pin connection(1284a) as a standard is found on the computer end of the connection. While the 36 pin standards(1284b and 1284c) are found on the device side of the connection. HP printers will either have the smaller 36 pin connection(mini centronics or 1284c) or the larger 36 pin connection(centronics or 1284b). Most other manufacturers used the Larger 36 pin connection(centronics or 1284b). Some devices do have a 25 pin connection on them, such as paralell zip drives, but they are the exception rather than the rule.
| Common Name | IEEE Name | Number of Contacts | Size of Connection |
| DB25 | IEEE 1284a | 25 pin | ~1 1/2 inches |
| Centronics | IEEE 1284b | 36 pin | ~2 inches |
| Mini-Centronics | IEEE 1284c | 36 pin | ~1 inch |
