On 09/06/2017 02:33 PM, Mia Magnusson wrote: > Den Mon, 4 Sep 2017 19:19:55 +0200 skrev Gerrit Heitsch > >> I remember the reason was to eliminate dot crawl. And since they >> needed this disrecte PLL with the 74LS629 and the MC4044P for a >> while, it can't have been cost reduction. And I also remember one >> engineer saying that he now considers running the VIC with 2 >> different clock signals a mistake. They fixed it in the 264 series, >> there TED gets the 14.318 or 17.734 MHz and does the rest internally. >> The Amiga also runs everything from a single clock source. > > I'm not sure about the NTSC video output of A1000, and not sure about > the built in stuff in A600 and A1200, but every other Amiga doesen't > have any color clock at all as it only outputs RGB (and in some cases > luminance+sync on a RCA jack). Not quite true... All NTSC Amigas use a crystal with 28.636 MHz which is the NTSC color clock multiplied by 8. So there is color clock used, just not to encode the output signal. :) PAL Amigas use 28.375 MHz, which is about 6.4 times the PAL color clock. But in the text above I was only talking about the C64 and why they used this rather complex discrete PLL to derive the system clock from the color clock. Gerrit Message was sent through the cbm-hackers mailing listReceived on 2017-09-06 14:03:02
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