Path: csiph.com!news.swapon.de!aioe.org!.POSTED!not-for-mail From: Brian Patrie Newsgroups: comp.sys.apple2.programmer Subject: Re: Reading the state of VBL on a IIc,IIc+. Date: Tue, 9 Oct 2018 13:19:44 -0500 Organization: an elaborate system of piles and accidents Lines: 33 Message-ID: References: NNTP-Posting-Host: /gViJJjsHbs1CAVxE5oNRA.user.gioia.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-Complaints-To: abuse@aioe.org User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 Content-Language: en-GB X-Notice: Filtered by postfilter v. 0.8.3 Xref: csiph.com comp.sys.apple2.programmer:4816 On 2018-10-08 15:18, Michael J. Mahon wrote: > Brian Patrie wrote: >> Thanks, Antoine, and Frank. >> >> (FWIW, my main use-case is pacing a timeout in a key input subroutine.) >> > > This reminds me of a discussion I had several years ago, when I was > building the graphical interface for a 4x4x4 3D Tic-Tac-Toe game. > > The game code was pretty processor intensive, and so would benefit from a > Zip Chip-style speedup, but the animations were for user interaction, so I > wanted the video to run at standard speed (as occurs with any Apple II > accelerator). > > Since I anticipated that the game would often be played on an emulator, I > asked whether any emulators with acceleration kept the video speeds > standard. > > At the time, I was told that emulator acceleration was “across the board”, > and that nothing equivalent to a hardware A2 accelerator was provided. > Needless to say, that precluded any “real time” (as opposed to accelerated) > animation. > > It seems that your desire to use VBL sensing for a “real time” timeout > might run afoul of the same problem if run under accelerated emulation. > > I still think it would be a great idea for emulators to provide a Zip-style > processor acceleration in addition to the usual “everything speeds up” > modes. As Kent says in another reply, KEGS and its descendants do. AppleWin, does not (which can be good or bad, depending upon the needs of the moment).