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Newsgroups: comp.sys.sinclair
From: Alvin Albrecht <aralb...@interchange.ubc.ca>
Date: 2000/05/16
Subject: Re: RFC: ULA Replacement for ZX Spectrum SE
kio (Günter Woigk) wrote: In the ts2068 there are two display files: the normal one > mode 1: (text mode) could be 512x192 like Sam Coupé or Timex2068. How is > this screen organized im ram? color? layout? size? at #4000 and a second identicaly formatted one at #6000. In one mode, the active display file can be swapped as in the 128k spectrum. In another mode, the pixel byte is taken from the first display file and the corresponding attribute is taken from the second display file. This yields 256x192 pixels and 32x192 attributes. The 512x192 mode uses the first display for even columns 0,2,4,..,62 and the second display file for odd columns 1,3,5,..,63. This way the SCLD (ULA) fetches alternating bytes from the first display file and the second one with the address for the second byte formed by setting bit 13. > mode 2/3: no attribute table but 8 bit per pixel indexed colors. The problem with such a high resolution display is that > (49152 bytes) > all those special switches could be added step by step. so lets start > with the color palette thing first. the spectrum is too slow to make use of it. Even doubling the clock frequency won't help since this display requires 8 times as much processing. I think we should be thinking in terms of hardware that will do all the work for us. Alvin You must Sign in before you can post messages.
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