The Pegasus 400 is a small 7.5cm x 14.5cm x 1.5cm creme coloured interface which plugs into one of the expansion slots on the Acorn Electron 1/AP1 or Rombox+ interface.

The Pegasus 400 is a DFS E00 interface. Although it does use some of the Acorn Electron's memory locations for its operation, it does not require any of those between &E00 to &1D00. This means many programs can simply be transferred from tape to a DFS disc and work from it. No complicated recoding is necessary. Every single disc in the archive will work on this format and the interface (or equivalent) itself can be considered a must have for a complete disc-based games collection.

The Pegasus 400 also boasts a spare 16K ROM socket which can be used to upgrade the interface with the T2PEG400.

The Pegasus 400 can be used with any Acorn disc drive that has its own power supply.

The Pegasus 400 came supplied with a DFS Manual.

The Pegasus 400 was originally available by mail order from Slogger for £69.99. For some reason, this interface seems to be much more highly regarded by collectors than any other, and a second hand Pegasus 400 will usually sell on eBay for £100-£200.