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Article #3224Re: Phi-2 Frequency on the CIA-B Chip
From: Raymond S. Brand
Date: Mon, 09 Apr 1990 14:50
Date: Mon, 09 Apr 1990 14:50
23 lines
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1553 bytes
In article <10713@netcom.UUCP>, mcmahan@netcom.UUCP (Dave Mc Mahan) writes: > I have written a short test program that measures the frequency of the Phi-2 > clock signal on the CIA-B chip. With repeated measurements over varying > periods of time, I keep finding the clock frequency is about 713 KHz. Is this > correct? I would have guessed that it is either the system clock (7.14 MHz) > or the colorburst frequency. Are my math calculations wrong? If it IS > 713 KHz, where is this generated from? > > -dave On an NTSC machine the Phi-2 clock (E-Clock) will be at 715909hz and on a PAL machine it will be 709379hz. On 68000 based motherboards this signal comes from the E pin of the 68000, which is the processor clock divided by 10. BTW, the CIAs may be clocked at different rates on future machines. rsbx ------------------------------------------------------------------------ Raymond S. Brand rsbx@cbmvax.commodore.com Commodore-Amiga Engineering ...!uunet!cbmvax!rsbx 1200 Wilson Drive (215)-431-9100 West Chester PA 19380 "We're working on it" ------------------------------------------------------------------------
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!cbmvax!rsbx From: rsbx@cbmvax.commodore.com (Raymond S. Brand) Newsgroups: comp.sys.amiga.tech Subject: Re: Phi-2 Frequency on the CIA-B Chip Message-ID: <10714@cbmvax.commodore.com> Date: 9 Apr 90 14:50:55 GMT References: <10713@netcom.UUCP> Organization: Commodore, West Chester, PA Lines: 23