Amiga, 68000 and CPU speed

SilentBob · 14 October 2006, 21:03

Over the years I've repeatedly noticed that CBM (and others) have used the 7.14 MHz figure when citing the speed for the 68k CPU based computers, when the real speeds are 7.09 and 7.16 MHz for PAL/NTSC respectively. I know it's no big deal, but I've always wondered why this number came into use. Was it so people would just have to deal with one specific frequency instead of two?

boing_1000 · 14 October 2006, 21:39

Good point. I don't get it either. It never really crossed my mind since I doubt it really matters, It's more or less to do with electrical standards since PAL is 50 Hz and NTSC is 60.

SilentBob · 14 October 2006, 21:42

Yes, the PAL/NTSC thing is exactly why I don't get where the 7.14 MHz thing came from. That clock frequency doesn't exist in any Amiga tech manual I've read.

musashi5150 · 15 October 2006, 15:45

It's a good point SilentBob... I had a theory that 7.14 might be the magical average Amiga speed (between PAL & NTSC)...

So, in an attempt to find an average I did:

(7.09 + 7.16) / 2 = 7.125

I was hoping the average would be the magical 7.14 - but alas, it's not

So I don't know the answer either

14 October 2006, 21:03	#1
SilentBob Junior Member Join Date: Nov 2003 Location: Norway Age: 49 Posts: 246	Amiga, 68000 and CPU speed Over the years I've repeatedly noticed that CBM (and others) have used the 7.14 MHz figure when citing the speed for the 68k CPU based computers, when the real speeds are 7.09 and 7.16 MHz for PAL/NTSC respectively. I know it's no big deal, but I've always wondered why this number came into use. Was it so people would just have to deal with one specific frequency instead of two?

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14 October 2006, 21:39	#2
boing_1000 A1000 Addict Join Date: Jan 2006 Location: Eastern USA Age: 37 Posts: 567	Good point. I don't get it either. It never really crossed my mind since I doubt it really matters, It's more or less to do with electrical standards since PAL is 50 Hz and NTSC is 60.

14 October 2006, 21:42	#3
SilentBob Junior Member Join Date: Nov 2003 Location: Norway Age: 49 Posts: 246	Yes, the PAL/NTSC thing is exactly why I don't get where the 7.14 MHz thing came from. That clock frequency doesn't exist in any Amiga tech manual I've read.

15 October 2006, 15:45	#4
musashi5150 move.w #$4489,$dff07e Join Date: Sep 2005 Location: Norfolk, UK Age: 42 Posts: 2,351	It's a good point SilentBob... I had a theory that 7.14 might be the magical average Amiga speed (between PAL & NTSC)... So, in an attempt to find an average I did: (7.09 + 7.16) / 2 = 7.125 I was hoping the average would be the magical 7.14 - but alas, it's not So I don't know the answer either

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