On 2013-05-14, at 09:18, Gerrit Heitsch wrote: >>>> I had a moment of inspiration today (after Michau asked about the SX ROMs) to check how it is done in the SX (I thought it was like in the older 64s) and.. it occured that there are actually /two/ crystals piggybacked one on another and just three 74LS chips next to the passive stuff on the daughterboard called "clock unit". >>> >>> Would it be possible to post the frequencies of the 2 crystals and what 74LSxxx are on the clock board? >> >> One is phicolor (17.734 on PAL) the other one is dotclock (7.8819 on PAL )frequency. > > Ouch... It's already a bit of a pain to get your hands on a 17.73447 MHz crystal, but where do you get a 7.8819 MHz one? Well, unlike ICs, in the worst case crystals can still be grown for a desired frequency but I was rather referring to our earlier discussion about why CBM didn't simply put two crystals rather than presumably more expensive stuff in the first place and in the second they even decided to make a custom IC. It seems that the desired result can actually be relatively easily achieved with two crystals and some lightweight semis around. > Ok, if you had a 8701 around, you could use that one. ? I am not sure I understand. -- SD! Message was sent through the cbm-hackers mailing listReceived on 2013-05-14 12:00:03
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