Extended Basic is designed to overcome the limitations of Sinclair Basic on the ZX81. It enables some of the statements found in conventional Basic, but missing from the ZX81, to be used.

READ, DATA, RESTORE, DRAW, UNDRAW, IN, OUT and FILL are all provided. PRINT, CLS and SCROLL functions are included and work very much faster than their Sinclair counterparts, and utilise the whole screen too.

The interpreter is in 2.2K of machine code, situated in Basic line 0. The software is simplicity itself to use. No RAND USR statements or POKE commands. The extended Basic statements are written in REM lines and a simple GOSUB 0 causes the interpreter to execute all the new statements in the next REM line.

The REM lines can contain an unlimited number of extended Basic statements, separated by the usual ":", together with the necessary variables. Indeed, extended Basic REM lines look identical to multi-statement lines in conventional Basic.

The program is pretty well crashproof, any errors in the extended Basic statements are clearly identified by comprehensive error codes. The only problem I had was remembering to get back to single keystrokes after spelling out extended Basic statement REM lines.

The extended Basic graphic functions (DRAW, FILL, etc) are impressively demonstrated in two demo programs included on the cassette. The extended IN and OUT statements offer exciting possibilities. It should be possible to access any hardware directly and very quickly, (e.g. disks, sound generator, joysticks, measuring equipment, etc).

Mr. Beniest's English is far superior to my Dutch, and he must be forgiven for lapses in grammar in the instruction sheets that accompany the program. With a little thought, they can be deciphered.

Extended Basic is a first class program and excellent value. It could very well become the regulation programming enhancement for the ZX81.