Codescan offers a quick and easy method of entering and checking machine code, and will be of interest to those ZX81 users who write complete programs, or subroutines, in machine code.

During use, the screen displays the Codescan operating commands, together with a 'window' showing 24 addresses and their hexadecimal contents, with a cursor pointing to one of the addresses and the contents of the A, BC, DE and HL registers. The window can be scrolled up or down, and the cursor pointed quickly to any desired address, to enable machine code to be readily compiled and edited. The display and handling methods are excellent in this respect, and make Codescan a very easy-to-use program.

The emphasis throughout, is on user-friendliness. It comes complete with a clearly written instruction bookley, which contains an example program, through which the reader is taken, step-by-step, as an introduction to the facilities offered by Codescan. The program resides above RAMTOP in the ZX81, and so before loading the program, RAMTOP must be lowered.

Apparently, Codescan was developed by Ceran Software as an aid to their own programmers. It is certainly likely to be very attractive to any ZX81 programmer writing in machine code.

A useful and well-presented package.