Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!ut-emx!ccwf.cc.utexas.edu From: ifar355@ccwf.cc.utexas.edu (David H. Huang) Newsgroups: comp.sys.apple2 Subject: Re: Stellar 7 re-release Message-ID: <42185@ut-emx.uucp> Date: 6 Jan 91 21:37:05 GMT References: <60237@microsoft.UUCP> Sender: news@ut-emx.uucp Reply-To: ifar355@ccwf.cc.utexas.edu (David H. Huang) Organization: The University of Texas at Austin Lines: 26 In article <60237@microsoft.UUCP> brianw@microsoft.UUCP (Brian WILLOUGHBY) writes: >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. There is a CPU >time price. Moving from 320X200 with 16 colors to 320X200 with 256 >colors takes CPU time. Do you happen to know where this interrupt bit is located? I know it isn't the scan-line interrupt bit of the scanline control byte. Anyways, I wasn't aware that using multiple palletes required interrupts. I just set the lower nibble of the SCB to the pallete number, and everything works fine. I don't even have to mess with the VGC interrupt register to enable scan line interrupts. >Brian Willoughby -- David Huang | Internet: ifar355@ccwf.cc.utexas.edu | "My ganglion is stuck in UUCP: ...!ut-emx!ccwf.cc.utexas.edu!ifar355 | a piece of chewing gum!" America Online: DrWho29 |