Thanks Andy
From which:

One of the most important features to note here is that the entire data transfer occurs within one ISA I/O cycle. The effect is that by using the EPP protocol for data transfer, a system can achieve transfer rates from 500K to 2M bytes per second. In this fashion, parallel port peripherals can operate at close to the same performance levels as an equivalent ISA plug-in card. The ability to get this level of performance from a parallel port attached device is one of the major features of the EPP protocol. With interlocked handshakes, the data transfer will happen at the speed of the slowest of the interfaces, the host adapter or the peripheral device. This "speed adaptive" property is transparant to both the host and peripheral. All 1284 transfer modes are implemented with interlocking handshakes.

Steve