Get in CONTROL!
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This issue I'm going to take a look at the facilities offered by Les Greenhalgh's CONTROL extension. (Version 3.6, registered).

At it's most basic, the CONTROL extension provides a number of commands which can be used to improve the structure of your programs, (eg:- 'case' and 'switch'), a command to write strings of text anywhere in memory ('write'), a command to add one variable to another, but keep it within a specified range ('add(a,i,l,r)'), commands to move and restore the cursor position ('cmove', 'cremember' and 'crecall') and the useful 'exist$' which can be used to check for the existance of files.

It also contains commands to drive joysticks plugged into the parallel port via a special adaptor, zone commands which allow up to 65536 zones to be defined, a command to pack or unpack Crack Art screens, a palette manipulation command ('spread'), a command to remove the screen borders on an STFM ('brdr remove'), a 'quick screen$' command which is much faster than it's STOS equivalent and the command 'hscroll' which performs smooth horizontal scrolling on a standard 320 by 200 sized screen.

Delving deeper however, (and preferably registering your copy) will reveal a wealth of very powerful commands. For example:-

* The extension contains a complete sprite engine which is much faster than the original STOS one and has the ability to flip sprites vertically. This means that you might not need both upward and downward facing sprites.  Clipping and collision detection commands are provided, as are commands to get sprite sizes and palettes.

* A complete set of mapping commands are provided which are not restricted to using 16 by 16 pixel blocks unlike the Missing Link commands. An accessory is provided which enables you to design your own maps. It is even easier to use than the Missing Link map editor and uses the concept of layers.

An accessory is supplied which enables you to create banks of sprites, blocks or fonts very easily. The biggest advantage of all the sprite and map commands is that they can work on non-standard screen sizes, so you are no longer restricted to 320 by 200 in low resolution. The extension also contains commands to set large virtual screen sizes and to use the blitter along with hardware scrolling in all directions on suitably equipped machines. You can also use the blitter to copy large sections of memory around ('bigcopy') or to clear it ('bigcls'). A command is also provided to allow you to write 16 colour fonts from image banks onto large size screens.

A number of the commands are only available to registered users. The 'jagjoy' command for example, enables your programs to support the jaguar joypad controller, 'turbocopy' is a very fast copier of 320 by 200 screens and many of the advanced mapping and sprite commands are only available to registered users.

Registration is only a few pounds and considering the large amount of work that has gone into the extension, the power of it's many commands and the fact that Les provides support for registered users, it is well worth it and highly recommended.

Next issue I'll be taking a look at the latest versions of Anthony Hoskins excellent Falcon extensions.