Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!zaphod.mps.ohio-state.edu!ub!uhura.cc.rochester.edu!rochester!pt.cs.cmu.edu!o.gp.cs.cmu.edu!andrew.cmu.edu!jh4o+ From: jh4o+@andrew.cmu.edu (Jeffrey T. Hutzelman) Newsgroups: comp.sys.apple2 Subject: Re: CPU speed detection Message-ID: Date: 7 Dec 90 22:25:58 GMT References: <9012052301.AA15585@cs-sun-fsa.cpsc.ucalgary.ca> Organization: Carnegie Mellon, Pittsburgh, PA Lines: 18 In-Reply-To: <9012052301.AA15585@cs-sun-fsa.cpsc.ucalgary.ca> VBL is the only technique I can think of, except on the IIgs. The IIgs wait routine is independant of system speed, although I don't know what various accelerators will do to it. The //c DOES have a VBL; it just has to be "turned on." by initializing the mouse. You can then process VBL interrupts like any other interrupt. There is a discussion of how to identify and handle mouse interrupts, including VBL, in the //c Technical Reference Manual. I can email the relavent sections to you, if you want. Note that this technique does NOT require that you have a mouse; only that you initialize the moouse firmware to the "VBL-only" mode. You CAN determin which CPU type you're on, and use that to figure out which VBL to use. Finally, the delay produced by the wait routine is not guaranteed beyond the fact that it will be at least the time you specify. -------------------- Jeffrey Hutzelman America Online: JeffreyH11 Internet: jh4o+@andrew.cmu.edu BITNET: JHUTZ@DRYCAS >> Apple // Forever!!! <<