ADT is a ROM compatible with both the Electron and the BBC Micros and designed to be used with either an ordinary disc filing system or the advanced disc filing system. The ROM adds 32 new * commands which are available from within a program or directly from the keyboard.

Most of these commands use the disc filing system, but several don't, although I wouldn't really recommend it if you haven't yet upgraded to discs.

ADT is available as a ROM cartridge which plugs into the Plus 1 or as a bare ROM. This could be plugged into something like Slogger's Rombox, tested in the August issue of Electron User.

*HELP ADT reveals all the extra commands and their syntax. Several commands, *BACKUP, *BUILD, *FORM, *TYPE and *CATALL should be familiar. These have been included in the ROM as they aren't in the ADFS but are on the Welcome disc supplied with the Plus 3.

*BACKUP copies the contents of one disc to another. *BUILD creates a file, usually text, which can be executed when the disc is booted with SHIFT and BREAK. *CATALL catalogues the whole disc and *FORM formats a new disc. *TYPE displays a text file without line numbers.

There are several useful search commands. *DFIND searches a disc, *MFIND searches the memory and *BFIND searches a Basic program, printing out the address of all occurrences of a given string. The search can be for a hex or ASCII string.

Programs can be loaded and run at any address, relocation is automatic. *MLOAD loads a program while *MRUN loads, relocates and runs a program. This saves a lot of fiddling about with programs that have to run with PAGE set to &E00 for example. Memory contents can be examined in hex, ASCII or assembly language with *MEX.

The disassembler is excellent and is the best I have seen so far on the Electron. It allows you to follow subroutines and branches by pressing the RETURN key when one is encountered. It even disassembles backwards!

A disc can be examined and edited with *DEX and sectors loaded and dumped with *SECTORS. *DUMP displays the contents of a file. I didn't realise how important these commands were until I accidentally saved one file with the same name as another. By examining the disc, I found the old program and used *SECTORS to load it back to PAGE and OLD to restore it.

*LIST lists a text file like *TYPE but adds line numbers. *VERIFY checks that a disc is OK. *FCOMP compares two files to see if they are the same and *DCOMP compares two discs. *SETADR changes the load and execution address of a file and *FCOPY makes a copy of a file.

Several commands act on ROMs. *ROMS prints all the ROMs present and *UNPLUG turns off a particular ROM. This is necessary if one ROM is interfering with the operation of another and can happen if two ROMs have the same name for two entirely different commands. Simply *UNPLUG the one you don't want.

*FREE displays the amount of free space on a disc and *MAP displays a map of free space. *FSN tells you which filing system is active and *XFER will copy a file from one filing system to another.

I've only briefly mentioned each command and given an indication of what it does. Many of the commands have several options and functions which are invoked by passing parameters and I haven't the space to explain in detail the full capability of such a comprehensive toolkit. Suffice it to say that it has just about every utility you're likely to need.

None of the utilities are new - they're all old hat on the BBC Micro. They are new on the Electron, however. The big plus point for this toolkit is that it's compatible with an ordinary DFS, the ADFS, the Electron, BBC Micro, and most commands work across the Tube.

One point worth mentioning though is that for some of the utilities to work in Modes 0 to 3, a link may need soldering inside the Plus 3 on the circuit board. However, all the commands work in Mode 6 whether the link has been made or not, so it's not all that important.

I found the ADT an invaluable tool. It saved time and effort and helped saved the day on several occasions. If you have discs, then you'll need a toolkit. Take a close look at Advanced Disc Toolkit - it's superb.

Roland Waddilove