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Article #3212Re: Phi-2 Frequency on the CIA-B Chip
From: LEEK
Date: Mon, 09 Apr 1990 17:34
Date: Mon, 09 Apr 1990 17:34
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1243 bytes
In article <10713@netcom.UUCP>, mcmahan@netcom.UUCP (Dave Mc Mahan) says: > >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 The Phi-2 (or 02) clock is generated by the E clock circuit on board the 68000. It is 1/10 of the frequency at the clock input pin of the 68000. It allows the 68000 to use the older 6800 series perpherial chip. In this case Phi-2 = 7.16 MHz/10 = 716 KHz. So your calculation is very good !!! K. C. Lee No disclaimers because no ideas were expressed... :)
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Path: arc1-ca.pugleaf.net!utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!qucdn!leek From: LEEK@QUCDN.QueensU.CA Newsgroups: comp.sys.amiga.tech Subject: Re: Phi-2 Frequency on the CIA-B Chip Message-ID: <90099.133437LEEK@QUCDN.BITNET> Date: 9 Apr 90 17:34:37 GMT References: <10713@netcom.UUCP> Organization: Queen's University at Kingston Lines: 20