Path: utzoo!attcan!uunet!ginosko!gem.mps.ohio-state.edu!rpi!pawl!shadow From: shadow@pawl.rpi.edu (Deven T. Corzine) Newsgroups: comp.sys.amiga Subject: Re: Denise/Paula/Agnus/Gary/Portia Message-ID: Date: 20 Aug 89 05:38:38 GMT References: <1388@bnr-fos.UUCP> <713@neptune.UUCP> <8566@batcomputer.tn.cornell.edu> <3036@bucsb.UUCP> <15769@watdragon.waterloo.edu> <506@tardis.Tymnet.COM> <13167@well.UUCP> <522@tardis.Tymnet.COM> Sender: usenet@rpi.edu Distribution: comp.sys.amiga Organization: Rensselaer Polytechnic Institute, Troy, NY Lines: 57 In-reply-to: jms@tardis.Tymnet.COM's message of 19 Aug 89 21:49:22 GMT Deven> The proposed scheme was to make one large bitplane (as far as Deven> the blitter is concerned) and manipulating the Copper to Deven> display the bitplanes, resetting the address for each line. On 19 Aug 89 21:49:22 GMT, jms@tardis.Tymnet.COM (Joe Smith) said: Joe> Summary: No need to use the copper Joe> Actually, my idea doesn't need to bother the Copper at all. Just Joe> set BPL1MOD and BPL2MOD (registers 108 and 10A). Okay, I stand corrected. [still, I had the right idea...] :-) Deven> <---------- layout in memory ---------> Deven> +---------+---------+---------+---------+ Deven> | | | | | Deven> | | | | | Deven> +---------+---------+---------+---------+ Deven> <--bp0--> <--bp1--> <--bp2--> <--bp3--> Joe> That's a good diagram. Gee, thanks! :-) Joe> The Blitter can handle this format if BLT[A-D]MOD are set Joe> (registers 060 thru 066). Again, no Copper hacking is required. On the other hand, if you *want* to do copper hacking, [:-)] you could use a scheme suggested earlier by someone to scroll by manipulating the addresses the copper displays from... Can you say FAST scrolling, boys and girls? [it requires only register shuffling, not memory copying] Of course, that would only really work as a screen, and might be hard to get it to cooperate with Intuition, but it would scroll quickly and smoothly... Deven> Now, to scroll, the blitter is told to scroll a region starting Deven> at addr, len*3 bytes wide and y lines long vertically by the Deven> height of a line of text. It doesn't matter to the blitter Deven> that the region is not displayed as a single bitplane. Joe> Right. The only problem, as I mentioned, is that the current Joe> Agnus has a limitation of 1024 bits for the total width. However Joe> the new 1-meg Agnus is supposed to respond to requests for 32K Joe> bit wide blits. 1024 bits not being enough for 2 hires bitplaces. *sigh* It's a nice idea, anyhow. You could do 3 lores bitplanes this way, but it's tough to do 80 columns that way... Deven -- Deven T. Corzine Internet: deven@rpi.edu, shadow@pawl.rpi.edu Snail: 2214 12th Street, Troy, NY 12180 Phone: (518) 271-0750 Bitnet: deven@rpitsmts, userfxb6@rpitsmts UUCP: uunet!rpi!deven Simple things should be simple and complex things should be possible.