Scor­pio News

procedure is excellent, even if it does make my old chaining method obsolete. It has the added advantage over my offering that it works on any disk drive, not just drive A. The speed at which programs stored on a MAP 80 ramdisk chain one another is truly inspiring for all those who are intending to write large systems of programs. Many people wonder when I will actually get round to writing a large system of programs, but I say to them, patience. After all, the OU keeps me rather busy at this time of year, and I have not yet finished my Prestel program…

All the programs I have written with this compiler have done what they were supposed to, except when the compiler didn’t realise what I meant, and did what I had said. That sort of machine intelligence is a few weeks away, at present. I have had a slight difficulty with my version of CP/M not behaving properly when the menu system is running, but it works with older CP/Ms, so it isn’t the Pascal causing the problem. I hope to sort this one out soon, and if there is any useful advice to share, I will pass it on. The compiler gets my recommendation. There are more expensive Pascals around, but I don’t know of any that can be definitely said to be better. Go on, somebody, tell me I’m wrong…

SVC Graphpac – alias GM575

I have been generously supplied with a copy of Gem-Graphpac to try out on my Gemini GM832 SVC video board. It always surprises me how few software authors want their products to be reviewed. I wrote to a supplier of Pluto software, suggesting that they might like me to write about their product, but they never answered my letter. I can only assume that they don’t like my style, or that there may be something horribly wrong with their product and they don’t want me warning you.

Meanwhile, enough sidetracking and beck to the subject in hand. Graphpac works with Microsoft’s MBASIC interpreter and an SVC, to allow easy control of the SVC’s extensive graphic ability from programs written in (takes stiff drink) BASIC. Actually, it reminds me of something I once wrote to go with Nascom BASIC, called Vortex, except that Vortex was rather clumsy by comparison. Anyone still use Vortex?

The software automatically links itself into MBASIC for you, and has the effect of adding a large number of new commands to the existing BASIC ones. Graphpac is able to set, reset, invert or test any pixel on the screen; it is also able to draw lines using either rectangular or polar coordinates. There are two resolutions, 256 x 256 or 160 x 75 using block graphics. In either case the top left of the screen has coordinates 0,0. Circle and arc drawing are also included, and can use either a Graphpac routine or the SVC’s own faster routines. Various routines for screen handling are included, such as SCROLL followed by a number, which sets up the SVC so that only the specified number of lines at the bottom of the screen will scroll.

Graphs, in the form of vertical bar charts, are specially provided for, using either solid bars or half tone. Although the results are not as sophisticated as graphs drawn on QLs (a good machine, even if it did have a plastic case), they are a great deal better then no graph at all. The ones in the demo program on the disk were quite effective, and the firm was obviously doing very well. Odd, isn’t it, the way these profit graphs always go uphill? Once you have created a work of art on screen, you won’t went to lose it forever, so the PSI and GSI commands which put and get a screen image will come in handy. Given the speed of the SVC, it comes as no surprise that these are quick. Another very handy facility enables full use to be made of the large number of SVC commands that are accessed by ‘printing’ escape sequences.

Provided you have an SVC and MBASIC, Graphpac de more or lees an essential buy, particularly as it is sensibly priced. I with Vortex had been as good!