One of the major faults on the otherwise excellent Advanced Disc Filing System in the Acorn Plus 3 and Pres's Advanced Plus 3 is the large amount of memory it requires for its workspace. When the ADFS is initialised either on power up or after a CTRL-BREAK reset, it grabs 3.75K of memory.

This means that in Modes 0 to 2 only 4,864 bytes are free, which isn't much, so many games and other programs and utilities simply won't work when transferred to disc.

Now this problem has been overcome by ACP/Pres, the company that has taken over production of the Plus 3 in a slightly modified form.

This is a major achievement, and many Electron owners will be jumping for joy at the news. The solution isn't that expensive either. The new ELECTRON ADFS E00 is supplied on a 3.5" or 5.25" disc, so you'll need either an original Acorn Plus 3 or Pres AP3 already if you are to make use of it. In addition, you'll also need the Pres Advanced Battery Backed RAM (ABB) cartridge.

If you've already got an ABR it'll cost you just £17.19 for the Electron ADFS E00 on disc, but £50.95 if you haven't. This sounds expensive, but the ABR has many other uses apart from the ADFS.

Installing it is easy - simply plug in the ABR cartridge and boot up the disc supplied. In use it appears to be no different to the standard Acorn ADFS, but one or two minor changes are worth noting.

A couple of serious bugs in the Acorn ADFS have now been fixed. The most obvious is that the ZYSysHelp file is no longer written to a freshly formatted disc.

The old ADFS was unreliable when writing to the first few tracks of a disc, so this was a "fix" and simply involved writing a file full of garbage to the suspect part. The ADFS would then skip it. Now you get the bonus of an extra 14K of disc space as Pres' version 1.26 of the ADFS correctly accesses all parts of the disc.

The other small but important improvement is that the cursor is switched off when you compact the disc - I've lost track of the number of files I've corrupted by compacting discs with that blinking cursor.

The main advantage of the Electron E00 ADFS is that fact that no memory is lost over a tape system. You can now load and run those long adventures and other programs straight from disc. Memory-based databases have more room to store data, word processors have extra space for text, spreadsheets can be bigger and so on.

An extra bonus is that the Winchester hard disc code has been taken out of the ROM, and the space used by adding the code to access the Pres Advanced Quarter Meg RAM cartridge as a RAM disc.

The disc containing the ROM image also has the Help, Welcome and Library directories from the Welcome disc supplied with the Acorn Plus 3.

So far so good, but are there any disadvantages? One point I found annoying was the fact that the ABR cartridge takes up a slot in the Plus 1, and on top of this both 16K banks of the Sideways RAM are occupied. Acorn Plus 3 owners won't be bothered too much by this as they still have a spare cartridge slot.

However, the Pres AP3 interface plugs into the other Plus 1 cartridge slot. This unfortunately means that the cartridge slots are all occupied and nothing else can be used. So View and Viewsheet are out, plus all the other peripherals and add-ons that make use of these slots.

The manual consists of a single sheet of paper, printed on just one side. However, this is all that is needed, as the Electron E00 ADFS can only be used wwith a Plus 3, and a manual will have been provided with that.

The Electron E00 ADFS and ABR costing £50.95 will give you 20,992 bytes free in Mode 6, and 8,704 bytes in Mode 0. An alternative would be to upgrade your Electron with a Slogger Master Ram Board costing £59.95. This will give you 25,344 bytes of memory in Mode 6, also the same in Mode 1, or any other for that matter, in addition to this, it will also speed up your micro to give you almost BBC Micro performance.

To sum up, if you've already got ABR, then the cost of the ADFS is a small price to pay for the extra memory and convenience of an E00 disc filing system.

If you haven't got ABR and simply want more memory for disc-based programs you've got a difficult decision on your hands: should you buy the ABR and Electron E00 ADFS, or stick with the original ADFS and upgrade with a Master Ram Board? The choice is yours.

Roland Waddilove