• EPP (Enhanced Parallel Port) protocol was developed by Intel, Xircom and Zenith Data Systems to provide a higher performance parallel port while still maintaining backward compatibility with the standard parallel port


• EPP is asynchronous, with interlocking handshaking and can operate bi-directionally. It supports half-duplex operation


• There are actually two versions of EPP:
  • EPP 1.7 - This is the version of EPP that came out just before the final version of EPP as specified in the 1284 protocol
  
  
  • 1284 EPP - This is the version standardised by the IEEE 1284 Committee
  
  
• Peripherals that are fully 1284 EPP compliant will work correctly with either an EPP1.7 or 1284 EPP parallel port host. Unfortunately, an EPP1.7 peripheral is not guaranteed to work when connected to a 1284 EPP port


• Using EPP, near ISA bus speeds may be achieved. This is because transferring data to or from the PC only takes a single ISA I/O cycle, allowing EPP ports to be used with network adaptors as performance is roughly that of an equivalent ISA PC card


• Depending on the type of parallel port and peripheral used, EPP communication can achieve data transfer rates of between 500,000 to 2,000,000 bytes per second (500KB/sec - 2MB/sec)


• Due to the enhanced performance of EPP it allows other peripherals such as CD-ROM readers, writers and tape backup devices to be used giving better performance and data transfer rates than standard parallel ports

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