The Electron is an impressive computer that is only just now being properly supported as a serious machine. With the inclusion of a Plus One interface (indeed, this forms the basis of many expansion operations on the Elk) you can expand the system to exactly what you require of a computer. If you need certain options you merely expand the system as you see fit by connecting expansion modules such as a Plus One interface.

Now that disc drivers have reduced dramatically in price, and you can pick up a good driver with a power supply unit for less than £20 these days, many Electron users will no doubt be very interested in a new disc interface from Solidisk technology, boasting a single 32K ROM containing the Solidisk DFS and DDFS as well as their totally Acorn-compatible ADFS. With the addition of some sideways RAM, you have a very comprehensive interface that can take care of just about any disc-based eventuality, especially as there is room for a Winchester disc drive as well.

Now if the prospect of connceting a Winchester disc drive to an Electron is a trend towards overkill, consider that with memory expansions and the inclosion of a 6502 second processor (either the PMS one or the Acorn BBC Micro version connected via the Advanced Computer Products Advanced Plus 5), you have a machine capable of running View, Viewsheet and Viewspell, all with the maximum amount of memory available to the BBC Micro; indeed, if you want to "re-map" the function keys, it is entirely possible to run the relocating version of View (Version 3.0) on the 6502 second processor to gain some 47,000 bytes free.

The EFS, as it is called, couldn't be easier to install. It consists of a small circuit board some five inches by two inches and plugs directly into a cartridge socket on the Plus One interface. There are two IDC sockets for connecting a single or dual 40 or 80 track disc drive. Should you want to connect, say two 40 Track single-sided drives, you could either fit the cables on yourself (and alter the dip switches on the disc drivers to read DS0 and DS1 for their respective drive surfaces), or you could take the easy option and plug in a Viglen "Duck", which will sort out all the disc decoding for you.

An aluminium "shell" is also included, so as to protect the disc interface from any stray knocks and bumps, and acts as a guide into the Plus One slot. The board itself fits into the rear most socket on the Plus One interface (slot 2) and once plugged in, can be forgotten about.

One of the nicest features about the Solidisk EFS is that it is a standard 1770 DFS, as supplied with the Solidisk BBC DFS and ADFS kits; this ensures total compatibility with discs read or written by any other BBC single density DFS, be it Watford, Acorn, Microware, Opus or Solidisk and, again, the ADFS is totally read/write compatible with the Acorn ADFS as supplied on the Electron, and the BBC Acorn Winchester disc system, Econet and Master series.

Many people's complaints about the Acorn ADFS are well founded, the most common one is that PAGE is raised to &1D00, which leaves the Electron user with very little memory, thus making it impossible to transfer much-loved games and programs to disc; this problem is solved by supplying a standard 1770 DFS in addition to the ADFS, which, although it lacks the friendliness and large capacity of an ADFS system, allows PAGE to be lowered to about &1100 (without any files opened with BPUT and BGET).

The STL ADFS has another advantage over that of the standard Acorn version, since there are a lot of the utility commands built into the 32K ROM, thus making the formatting of discs, verifying and backing-up of data far easier, and a good deal faster than with the Acorn utility disc.

As I mentioned earlier, the STL DFS was one of the first to be made compatible with the BBC Micro disc protection system which means that some commonly available discs may run where a cassette version of the software is known to execute properly. As a rule of thumn, games that require sideways scrolling generally don't work, but most Acornsoft games will run properly, especially the old favourites such as SNAPPER and the like.

The DFS will attempt to run the protection systems in Elite and Revs, this is not to say that BBC Elite will operate on an Electron - nor will Revs! - but the protection system (now accepted as standard by all but a few software houses) will be compatible. You can attach either 5.25" or 3.5" discs or even a combination of the two, so compatibility between both the Electron and the BBC disc drivers is also insured. But the EFS is capable of running a good deal more than just games. It will operate happily wth the complete View range, although Viewstore is yet to be properly "mapped" concerning some function key commands. The Acornsoft Database operates very well, especially when in ADFS mode and all my BBC Micro formatted discs were read both in 80 track and 40 track mode.

Of notable interest in the DFS's utilities section are commands that extend some ideas in the original unreleased Acorn 1770 DFS, namely *DDFS, which enters a double density mode of operation (MFM packing as usual). This allows the same amount of data to be stored as allowed in the ADFS, but with the same Acorn DFS standard - PAGE is not increased and the 7 character, 31 file limitation remains. Switching to a DDFS mode is automatic if a DDFS disc is installed.

*DOWNLOAD cures the problem of running cassette-based games on a disc system, as it loads the disc file into memory and then relocates it to the cassette filing system load address. This is supplied on many common disc utility ROMs such as Disc Doctor and is a great boon to those wanting to transfer their library of cassette-based games to the Electron disc system.

*DSTEP is a software "switch" to double step the motor, thus making it possible to read 40 track discs on an 80 track disc drive without having to physically flip a switch. Naturally this command is flanked by *SSTEP.

*DZAP is a fairly comprehensive disc sector editor, it allows you to examine a disc's status and how it may be possible to obtain lost data from the surface. If you *DELETE a file, then only the reference to that fiel is taken from the catalogue, the pointer to the old file is changed to a blank. So if you accidentally erased a file then, providing you haven't made any SAVE operations to the disc, you can retrieve it with a little careful catalogue editing.

*TAPEDISC allows most tape-based programs to be transferred to disc; this includes cassettes that are "Locked". If a file is left ambiguous (i.e. *TAPEDISC *.*), the complete tape will be saved to disc. With cassettes, a total of 10 characters are allowed for filenames; with disc systems, this filename is truncated to seven, so that *TAPEDISC command will cut a file such as "PROCESSORS" to "PROCESS".

*LOADTAPE is a little more sneaky as it attempts to load special format files, such as odd blocks in the middle of a tape file that switch from 1200 baud to 300 baud, and then up to 1200 baud again or tape files that rely on odd CRC data number (usually causing a Data? message).

*MVADFS is very useful if you want to transfer a file from DFS or DDFS to ADFS format. This command is the same as the Copyfiles utility bundled with the Master and ADFS disc.

*SPEED cures the problem of having to set the track stepping time of a particular disc drive and is a boon to Electron users who do not have access to a keyboard link, such as the one on the BBC Micro keyboard used to set the disc settle time and speed under varying controllers and disc drive types.

In addition to the utility commands there is a "word processor" on the disc. In reality, *WORD is a welcome alternative to the *BUILD command as it allows full screen editing of !BOOT and *EXEC files. This can be used to create a new document or to amend an old one and allows some useful editing commands. Annoyingly, View also requires the command *WORD to call up the cartridge, and slot 1 (the View cartridge slot) is given priority when it contains a device.

As mentioned earlier, the DFS will work with a second processor. Although I have only tried it out on the E2P processor extension (which is a precursor to the PMS Electron 6502 second processor), I would have liked to have tried the DFS with a Z80 second processor, as the manual claims compatibility with the Acorn Z80 version and fitting this via the ACP Advanced Plus 5 would be an extreme test of its compatibility. Still, the BBC Micro version of the STL DFS 2.1 (which the Elk version essentially is) operates correctly with most hardware extensions to the BBC apart from the Bitstik.

This is where the fun really begins. I tried a number of Winchester disc drives, all of which worked from a hardware point of view bar one. This was the largest I tried, a 20 Megabyte Winchester disc adapted from a Research Machine's 40z computer. It continually kicked up a few formatting errors that could not be removed. This is a complete mystery to both myself and Research Machines but we can only assume that the "last" track (an extra track placed on the disc by Research Machines) is interfering with the Acorn ADFS track selection on the ADFS's "last" track (which appears before the Research Machines track, and is not formatted).

Both floppy disc drives and Winchester discs require a separate power supply to serve them, as the Electron cannot supply enough juice to the expanded system. Thus, you are going to have to either get a separate power supply, if the drives you purchased plug into the auxillary power socket or you will have to get a power supply adapter from Pace or Viglen.

Using the ADFS is a little harrowing to begin with, being seemingly slow and cumbersome, but when one gets the hang of allocating sensible directory names and making copious use of the *CATALL utility on the Acorn ADFS disc) you will get on like a house on file!

The ADFS, especially the STL ADFS allows a sensible file hierarchy to be set up. I have not got directories set up for View, with sub directories of LETTERS, REViewS and BOOKS. This technique can be applied to other business tasks such as a directory for aCCOUNTS with sub directories of JANacc all the way up to DECacc, a whole year's accounts neatly stored.

Of course, with a single sided 40 track ADFS disc, you are only allowed some 160K, but even in this case you can divide the disc up into as many directories and subdirectories as can be physically accomodated, such as "Games", "Roms" and "Letters". The hierarchical directory approach is also a great boon for Viewstore users who need many filenames of the same name, but with different directories.

All of the usual ADFS commands are included, and like the STL DDFS and DFS, some extras are included as can be seen below:

STL ADFS 2.1 ACCESS <List Spec> (L) (W) (R) (E) ADFS BACK BYE CDIR <Ob Spec> CLOSE COMPACT <SP> <LP> COPY <List Spec> DELETE <Ob Spec> DESTROY <List Spec> DIR <Op Spec> DISMOUNT (<Drive>) EX <*Ob Spec*> FADFS FORM160 (<Drive>) FORM80 (<Drive>) FORM40 (<Drive>) FREE INFO <List Spec> LCAT LEX LIB <*Ob Spec*> MAP MOUNT (<Drive>) PASSWORD <Password> REMOVE <Ob Spec> RENAME <Ob Spec> <Ob Spec> TITLE <Title> VERIFY (<Drive>)

OS 1.00

Matthew FifieldClive Grace