Comment by illys | Hacker News Reader

Comment by illys | Hacker News Reader

I wonder about one thing...

If that exceptional talent and art-code were distributed in the 1980's, obvioulsly they would have had a large effect in many extends (inspiration to others on the platform, definition of new compatibility levels...), but what about distribution?

I feel the demo would have had very limited distribution due to the very restricted platform target: real IBM 5150/5155/5160 with original IBM CGA.

I think people of the time would probably have tried to make it work on a larger base since maybe 80% of XTs were not IBM's...

My question: what video modes and tricks are solid across most XTs and CGA cards of the era? I guess the 640x200 text mode with 8x2 chars is solid, but what about the other tricks? How portable are they?

Why not making a selection of 3 or 4 very popular and very different hardwares of the time as a target platform. For instance I think of IBM 5150 CGA + Tandy 1000 + Amstrad PC1512...

Most of the tricks in the demo should work unmodified (or could be made to work) on most CGA implementations of the era. Some clones had slightly different font ROMs so it would look a little bit wrong on those. The final lake effect (and the ripply picture shortly before it) use very tight cycle counting so probably won't work on anything except a genuine IBM PC/XT and CGA. Some effects (like the radial fire effect and the voxel landscape) should work on just about anything. The Amstrad PC1512 will have trouble with any effect that modifies the CRTC timing registers as it doesn't have a fully programmable CRTC and always generates a 15.7kHz/59.92Hz 640x200 image. I don't have personal experience with the Tandy 1000 and don't know how compatible it is off the top of my head.

Thank you for your reply, it is conforting to know the tricks are solid. Maybe it will help some retroprogrammed CGA games to appear with more colors and effects.

I have a VGA XT clone (4.77/8 MHz) and an ATI Small Wonder CGA clone board. I will try to bind them together and run Area 5150.

The ATi Small Wonder is not entirely cycle-accurate. When I studied the CGADEMO by Codeblasters, I found that the scroller didn't look entirely correct, because the Small Wonder was slightly slower: https://scalibq.wordpress.com/2014/11/22/cgademo-by-codeblas... It appears to insert a few extra waitstates compared to an IBM card. This may trip up some effects in Area 5150.

I wonder... certain software, such as Flight Simulator and Lotus 1-2-3 had a profound effect on the level of compatibility of clones. So perhaps if software was released that demanded EVEN MORE compatibility, we would have even more compatible clones than we do now?

Reenigne and Scali, I am very honored to have an answer from both of you :-)

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