THE NEW Kempston disc interface, a development of the Watford SPDOS, is one of the fastest interfaces we have seen for the Spectrum and it has some useful features.
Reliability proved to be a problem as the interface refused to work with either our own drives - used on all other Spectrum disc interfaces - or the Opus drive. That problem was eventually identified after trying three interfaces, and subsequent units should not suffer the same fate. If possible, either check with your own drive or buy the combined interface/disc drive package from Kempston. The interface was subjected to one of the longest tests we have ever given and it passed with flying colours.
At its simplest level, you can use the interface as you would a tape deck, to load or save a Basic program, Code or Data. You use the same commands as you would for tape but precede them by PRINT £4.
One useful byproduct of the system is that you can open channel three to a file on the disc. That means as this channel normally points to the ZX Printer, you can LPRINT to the disc and then later print out the file.
As well as Format, to initialise the disc, the usual Cat (display what is on the disc), Erase (delete a file from the disc) and Move (a file from one disc to another) are provided. They allow the use of wild-cards.
The interface has a number of extensions to Sinclair Basic. Clear can be used in two ways: Clear 0 will look through a Basic program and change all numbers to VAL "number", which saves three bytes per number. It also changes zero to NOT PI, one to SGN PI and three to INT PI which saves five bytes a time. On Tasword that saves about 1200 bytes, more than enough to offset the 703 bytes taken up by the interface.
The Kempston interface provides a fast and usable system. Provided Kempston can ensure the interface will work with a wide range of drives it should do well.
The interface alone costs £85, and a system including a 40-track drive is £185, both inclusive. It is not compatible with Interface 1.
Kempston MicroElectronics, Singer Way, Kempston, Bedfordshire MK42 7AW. Tel: 0234-856633.