80-Bus News


July–August 1983 · Volume 2 · Issue 4

Page 12 of 55

plotting was very fast indeed. The resolution was all it was supposed to be, the 640 x 288 format over filling the screen of the monitors used, and resolution patterns were just resolvable on the best monitors. I found the lack of circle drawing and fill routines a nuisance, but I suppose I could have fitted the extended command ROM (£50.00) had I wished, instead I pinched some of the machine code primitives from the Climax card and used those instead. The page memory system of the Pluto was very useful, it allowed preset shapes to be set up and used quickly, this is most useful for character sets which may be created in several fonts for use. The use of text in the 80 column mode was well displayed, but seemed something of a waste of a very expensive monitor if 80 column display were the only use of the card.

The Nascom Card.

The Nascom card plugged straight into a Nascom system and refused to work. This was traced to not having read the manual as a small mod. is required to the page modeing of the RAM card to allow the AVC to work without corrupting the existing system RAM. Having read the manual and fixed the RAM-card the AVC was well behaved and proved easy to use. The software supplied linked into the Nascom Basic transparently and provided all the expected functions. Overall the speed was good, not as good as the Pluto by a long shot, but adequately fast for most purposes. The main drawback as far as speeding up the card was not being able to make immediate use of the Nascom machine code primitives. Access to the primitives is via a jump table at the top of the workspace and although entirely possible by careful reading of the manual, the absence of the source listing made life difficult as a lot of preset registers required setting up before any primitive could be called.

Lots of fun was had using the port addressed colour changing facilities and a small binary adder was built to provide colour ‘rotation’, marvellous for making high speed animated wallpaper effects and baffling people who could not understand how the Nascom card did it. All round I don’t have any moans about the way the Nascom AVC worked.

The Climax Card.

The Climax plugged in and worked in a Gemini system straight away. The problems over the disk primitives was solved by spending an evening typing them in, and taking advantage of having to retype them by arranging them for easy assembly into stand alone machine code primitives if required. It seems that the disk of primitives are supplied as an optional extra at £15.00 + VAT, so if you value about four hours typing at more than £15.00, you’d better buy the primitives. The primitives automatically linked with both versions 5.12 and 5.2 of MBASIC with no trouble and provided most of the functions I required. Two notable ommissions I have supplied as source listings elsewhere in this rag, and Climax users may tag these straight on the end of the primitives as supplied, but note, the whole lot must be reassembled otherwise the relocator tables won’t be present.

The Climax was notable for its speed. Some of the functions were achieved (visually) instantly, the box drawing and filling routines were very impressive indeed. The method of sending instructions from Basic to the primitives used the Basic CALL function and was very efficient with one nasty snag. If the label called was misspelt or otherwise missing, then MBASIC would return to the operating system (being effectively a call to 0000H) thus losing the whole program. I soon learnt to save ALL programs to disk before running them!!!

Page 12 of 55