Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!samsung!zaphod.mps.ohio-state.edu!wuarchive!udel!rochester!uhura.cc.rochester.edu!ee.rochester.edu!seah From: seah@ee.rochester.edu (David Seah) Newsgroups: comp.sys.apple2 Subject: Re: Stellar 7 re-release Message-ID: <1991Jan3.183015.5321@ee.rochester.edu> Date: 3 Jan 91 18:30:15 GMT References: <60237@microsoft.UUCP> Organization: University of Rochester Department of Electrical Engineering Lines: 35 In article <60237@microsoft.UUCP> brianw@microsoft.UUCP (Brian WILLOUGHBY) writes: >scottg@gnh-starport.cts.com (Scott Gentry) writes: >>The standard resolution are: Any Apple II graphic mode, PLUS, Super Hi Res in >>320x200 with 16 colors and 640x200 with 16 dithered colors (Four pure colors). >>A variant that doesn't require special programing to display but requires >>special programming to create is 320x200 with 256 colors (16 palettes), or >>640x200 with 256 colors (16 palettes). People should really look at what can >>be done with 16 properly used colors. I know I was stunned. > >I think that you are overlooking a detail in the design of the GS. >Multiple palettes are enabled by setting an interrupt bit for >individual scan lines. This interrupt does, in fact, take CPU time >to handle, as all 16 color registers must be loaded for the new >palette. Just because all of this is set up by the system and not by >your own code does not mean that it is totally free. This is a new one to me. If one looks at the scanline control bytes, there is a 4-bit field for setting one of 16 palettes for each and every scanline. No interrupt is generated that the programmer must be aware of. As far as I know, no 65816 CPU cycles are used. On the videoDAC side, I have no idea, but I'm sure that it doesn't impose any interrupt burden on the CPU. >There is a CPU time price. Moving from 320X200 with 16 colors to 320X200 >with 256 colors takes CPU time. I'll always give someone the benefit of the doubt...what is taking the CPU time for 256 colors? -- Dave Seah ^..^ | Analog Design Automation Research Group - Graphics & GUI | | University of Rochester, Dept. of Electrical Engineering | ////// Internet: seah@ee.rochester.edu ////// America Online: AFC DaveS //////