Printers and other devices, which comply strictly to appropriate industry standards (e.g., EPP or ECP) can be attached via the ubiquitous USB cables with interface converters. The occasionally more important problem is supporting legacy devices, which employ the old-fashioned printer interface a non-standard way. In bygone times, the parallel port has been used frequently as a simple general-purpose programmable I/O interface with 12 output and 5 input signals.

It is not that difficult to emulate the parallel port by an Atmel AVR microcontroller. Two different units have been developed. One is the host; the other emulates a peripheral device.

The Host Adapter:

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The breadboard prototype of the peripheral device emulator:

March 2, 2015

• Emulating the ISA Bus
• Emulating the PCI Bus
• Legacy Home