The Abersoft implementation of Forth has been around for some time for the Spectrum, and it's not surprising that this version for the 64 has appeared. The package is distributed on cassette, but disc users need not worry since full details are given on how to transfer it to disc.

The package is an implementation of Fig-Forth with extensions for sound, sprites and graphics. Unlike normal Forth, however, RAM is used to store screens rather than virtual memory on disc or cassette. Whilst this is becoming more common with larger memory machines, other systems such as MMS Forth provide direct flushing to disc or cassette.

The additional words, particularly those for sprites and sound, are extensive. The graphics words are limited to simple high-resolution plotting and user defined characters.

For the serious user, a nice feature is the resident assembler. Once you get used to entering the mnemonics in reverse Polish style, this tool proves to be most valuable. The package is accompanied by a small instruction booklet which whilst appearing to be comprehensive, tends to be rather superficial and occasionally obscure. The section relating to the assembler is particularly poor. The booklet indicates that it isn't intended as a tutor for new users of Forth, but more details and examples wouldn't have gone amiss.

Notwithstanding the weak documentation, this is a powerful and effective implementation of this excellent language. A nice bonus is that a word - ZAP - is provided to save your games in a safe form if you wish to market them.

A.W.