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Old 04 April 2012, 17:48   #550
Join Date: Jun 2010
Location: out in the wild
Posts: 1,243
Originally Posted by d0pefish View Post
The Indivision as a product is primarily a scandoubler/flickerfixer, a device that takes the 15KHz TV-style horizontal scan rate of the Amiga and doubles it so that it works with PC monitors.
It does not double for all screen modes. Only old flickerfixers do that, but that would result in the 50Hz requirement that MrCheese was asking for. Since most monitors can't handle 50Hz, you're stuck with a very small choice. Indivision can not only double, but multiply with almost any factor. What I've promised for the first release is a 2.5 multiplier for the pixelclock, so a PAL screen is output at 62.5Hz, keeping tearing at minimum.

Also, you're mixing terms "scandoubler" and "flickerfixer" like many people do. Note that the first flickerfixers back in the days (over 20 years ago) were created in order to get rid of interlace-flicker. At some point, 15kHz-capable monitors became hard to find, and flickerfixers were still the only thing available for increasing the horizontal frequency to the minimum 31kHz that most PC monitors want to see.

During that time, flickerfixers were pretty expensive, so one of the companies was looking for a way to make PC monitors usable WITHOUT building a whole flickerfixer. The idea of a scandoubler was born: A cut-down design that doesn't store a whole frame, but only a single line and outputs it two times at twice the pixelclock. This made early startup menu and simple games visible on cheap PC monitors.

Note that during that time, even flickerfixers did not store a full picture, but had barely enough memory for one frame (half a picture!) and one line. This is enough to build a syncronous flickerfixer, but it was still very expensive due to the high speed and dual-port requirement of the memory chips.

Using the term "scandoubler" for something that's even more sophisticated than the flickerfixers of the Amiga haydays is a little off track. Indivision uses a full framebuffer at even higher speeds and full colour depth, so it does *more* than a flickerfixer back in the days, and it does *way*more* than a scandoubler.

Originally Posted by roy bates View Post
is there any chance jens can post a list of of modes and what there upscaled to?
Indivision AGA was the first flickerfixer ever to support all Amiga screenmodes but A2024. Indivision AGA MK2 will follow that lead.

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