There have been numerous times, when writing a program in BASIC involving graphics, that I have wished I possessed a better knowledge of machine code, so I could speed things up.

Line and circle drawing along with plotting and filling shapes have always caused me headaches, but at last someone has come up with some ready-made routines that will do all of these and a lot more besides.

McVid, from Pica Software, consists of a 45 page manual along with either a cassette or disc containing the routines and some sample programs.

The manual starts off quite rightly by warning you that a reasonable amount of knowledge of machine code is needed to take advantage of the routines at all. Furthermore, a good knowledge of machine code is required to be able to understand how they work. This is very true, so don't get the idea that the package will enable you to write dazzling arcade games with little or no previous knowledge of assembler, because it won't.

What it sets out to do, and does quite admirably, is provide routines which students of machine code can analyse and play around with to increase their knowledge. They can then modify and incorporate the routines into their own programs.

The way this is achieved is by the provision of listings of the source code of all the programs on the disc, which are fully documented, line by line, with further explanations in the text of the manual. The text explains very thoroughly how you can go about modifying and using these routines in your own programs.

The manual takes you through the processes of line drawing, sprite drawing, screen scrolling and circle drawing and filling. These are dealt with for all graphics modes and there is a sample routine on the disc for each one.

Also on the disc or cassette is a sprite definer and line definer which I found really excellent, enabling the writing of some pretty impressive graphics even when used only from BASIC.

In the main, I found this whole package very useful and easy to follow though I would warn you to look carefully through the manual if you are considering purchasing. I think it will definitely appeal to the student of machine code who is looking for an insight into some of the more complex tasks using assembler.

Peter Rochford