Path: csiph.com!eternal-september.org!feeder.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: mmphosis Newsgroups: comp.sys.apple2.programmer Subject: Re: Vertical Blank on Apple ][+ Date: Fri, 26 Aug 2016 18:52:19 -0000 (UTC) Organization: Mac GUI Lines: 27 Message-ID: References: <4b75fac1-2004-4e0b-b9e2-5dd131af84b5@googlegroups.com> <97a18b62-991f-4901-9ed6-be1e6bef4cad@googlegroups.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Injection-Date: Fri, 26 Aug 2016 18:52:19 -0000 (UTC) Injection-Info: mx02.eternal-september.org; posting-host="ac9e0e4d7dd3957fb97803ee6801bab8"; logging-data="10534"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19D4cQ4vQEdC2+1sOiSvibv" User-Agent: Mac GUI Usenet In-Reply-To: <97a18b62-991f-4901-9ed6-be1e6bef4cad@googlegroups.com> Cancel-Lock: sha1:coVM/2Dy7ReTbCTsQ6VBY6SJrjM= Xref: csiph.com comp.sys.apple2.programmer:3023 > Has anyone determined what size of area can be drawn within a vertical > blank period? 4550 cycles = 65 cycles * 70 lines, from: http://rich12345.tripod.com/aiivideo/vbl.html And, 4550 cycles is just the VBL period, you can get more cycles (17030 total) by "racing the beam" as others have mentioned -- and that's at 60 frames per second! As, for how much screen area can be painted in 4550 cycles? Coding for speed: 1137.5 bytes = 4550 / 4 cycle STA absolute instruction That's painting more than the entire GR, GR2, TEXT or TEXT2 screen with the same byte. Or, you could paint over an eight of the hi-res screen with the same byte. I think an interesting thing to do would be to flip the graphics modes while racing the beam: https://www.youtube.com/watch?v=KD6ocf_0Bkw