Re: Apple II Disk Drive Question

[Don Bruder <dakidd@sonic.net>]

In article <1hc5pp1.ked6xj1br0avnN%dempson@actrix.gen.nz>,
 dempson@actrix.gen.nz (David Empson) wrote:


> There is a bit on page 9-45 (with reference to the ProDOS driver) which
> says that the maximum variation due to rotation speed and disk flutter
> must be less than plus or minus 4.7%.  This translates to about 2.3%

There's no nicer way to put this, and I've seen you making the exact 
same *JUST PLAIN WRONG* statement multiple times now, so I'll just be 
blunt:

It doesn't "translate" to anything, period. "+/-4.7%" explicitly states 
that 4.7% below OR above 300 RPM is acceptable - no translation required 
- There's an explicit 9.4% window, with the target speed of 300RPM 
centered in it. 

It does not say anything about 2.3% - If that were the intent, there 
would be no "+/-" involved - it would be a straight "4.7% variation". 

4.7% of 300 is 14.7. Therefore, 300-14.7 = 285.3, and 300+14.7 = 314.7, 
meaning any speed from 285.3 to 314.7RPM is within specs. 

Your incorrect interpretation of what's spelled out explicitly in black 
and white narrows that range considerably - 2.35% of 300 = 7.05, making 
minimum RPM under your interpretation 292.95, and maximum 307.05.
Yes, it's a tighter tolerance. But it's not the tolerance specified.

I know that's nit-picking, but if you're going to throw math around, at 
least get it right, huh?

-- 
Don Bruder - dakidd@sonic.net - If your "From:" address isn't on my whitelist,
or the subject of the message doesn't contain the exact text "PopperAndShadow"
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ever knowing it arrived. Sorry... <http://www.sonic.net/~dakidd> for more info