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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Daff on October 22, 2012, 07:37:37 PM
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Hello,
When reading different articles and docs about the Amiga 500/600/CDTV, etc. we can see there are two different frequencies for the 68000 in NTSC Amiga models : 7,14 MHz and 7,16 MHz (7,15909).
The master clock in NTSC models is 28,63636 MHz which is divided by 4 : so we have 7,15909 MHz for the 68000 processor.
But a lot of articles say it's 7,14 MHz :
http://amiga.resource.cx/mod/a600.html
http://amiga.resource.cx/mod/a500.html
http://fr.wikipedia.org/wiki/Amiga_500
http://www.amiga-resistance.info/bboahfaq/index.php?sid=444372&lang=de&action=artikel&cat=7&id=1865&artlang=de
http://www.amiga-resistance.info/bboahfaq/index.php?sid=444372&lang=de&action=artikel&cat=7&id=1870&artlang=de
http://www.amiga-resistance.info/bboahfaq/index.php?action=artikel&cat=7&id=1863&artlang=de
etc.
Some says it's 7,16 MHz
http://en.wikipedia.org/wiki/Amiga_500
http://en.wikipedia.org/wiki/Amiga_1000
Even some articles says it's both :
http://www.amiga-resistance.info/bboahfaq/index.php?action=artikel&cat=7&id=1845&artlang=de
So my question is : which frequency is the good one ?
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The Wikipedia looks more correct, because is specific on exact frequency and then the frequency is shorten to 2 decimal places.
I could take my frequency counter and measure the exact frequency to be 100% correct :)
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The schematics show precisely 28.63636 MHz for NTSC and 28.37516 MHz for PAL:
(http://wowohl.de/pix/amiga_clock.png)
and everything else is derived from that (except for asynchronous accelerators).
btw: the oscillators have their frequency printed on them