80-Bus News

  

January-February 1984, Volume 3, Issue 1











Page 21 of 55











21

with this improved display speed is that fingers 2 and 4 on my left hand had to increase their reaction time by a proportional amount, as there was barely time to bash “S before the thing you wanted to see disappeared off the screen. Perhaps a ZZzzz... command could be built into CCPZ to slow it up when not actually executing a program.

The next feature investigated (for its novelty) was the clock display. Once enabled, a changing clock display is written at a user predetermined cursor position on the screen. The default cursor position is the extreme top right hand corner of the screen, and this suits most software I had a chance to try it with. The internal clock generator is interrupt driven from the frame sync-, which is divided by 50 to update the clock counter and redisplay the clock once a second. As the system clock is crystal controlled, it is accurate enough for most purposes although I think reprogramming the 6845 video controller could upset the clock accuracy. A very simple routine was written which read the time from the GM822 RTC and loaded the clock on the svc. At the end of the two hour period there was a discepancy of 7 seconds between the RTC and the SVC clock.

A number of bits of software which were known to be to greater or lesser extent video card dependant were tried to see if the compatibility between the CGM832 and the now discontinued GM812 were as claimed, and all were found to work as before. DISKPEN/GEMPEN required adjustment to the cursor speed patch byte, because the cursor flash rate went berserk, but in all other respects except the 48 wide mode (the new SVCs second screen mode is now 40 wide) DISKPEN/GEMPEN worked well. The increased speed of the card showed to advantage with WORDSTAR, screen rewrites being accomplished with very acceptable speed. My old CHARGEN program for reprogramming the character sets worked, but of course needs rewriting in the light of the SVC as there are now two programmable character sets (total 256 characters) instead of one.

The SVC has a number of new features including 256 by 256 pixel graphics with built in line and circle drawing software, selectable attributes for flashing characters with low, half and inverse intensities, inputs for serial keyboards, and many other things. As I said, I only laid hands on one for a very short period, so it is very difficult to be objective. I didn’t find any nasty quirks and the board behaved impeccably. Perhaps now Gemini will loan me “one to play with, and I’1l be able to find out what it can really do. The only thing that worries me though is the very high degree of sophistication of this card, commensurate with its elevated price. In my experience, 992% of users were unaware of the potential of the old GM812 card, so is all this cleverness

really necessary?

The Climax colour card

The Climax colour card is to be re-introduced. Gemini have acquired the rights to manufacture the card from Climax, and deliveries are to commence ‘very shortly. This card was very popular with those owning it, and some very clever displays have been seen. But as the card has been unavailable for the best part of a year, interest in it has waned. With its welcome reappearance perhaps some new and clever software will start to be written. Certainly as the video format of the Climax card is the same as the high-res mode of the new SVC, there will be demand for a piece of software which will act as an interface between the two. Here is an opportunity for CC-SOFT, who have written some rather nice graphics software for Gemini gear in the past to come up with something. It would be nice to see two interfaces with common inputs


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