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Old 1st Aug 2019, 10:25 pm   #3
Argus25
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Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
Default Re: Early S-100 Graphics cards.

Quote:
Originally Posted by NealCrook View Post

I was intrigued to see that "clear all pixels" and "set all pixels" are apparently implemented in hardware. Can you explain how they work? I speculate that they jam 0 or 1 on the write port to all rams and somehow reuse the video readout address counters to cycle through writing all addresses during the course of one frame time.

Regards

Neal.
It is a very useful feature to clear the screen before writing the image. I'll have a look a the schematic and see if I can figure out exactly how they did it, you are probably correct. The feature (bulk erase) is the same on both cards, but on the 512 you have to also select the plane register first.
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