On Mar 5, 8:17 am, Nate Raymond <[email protected]> wrote:
> I'm not sure regarding lettering codes, I'd have to look up their meanings
> for Motorola parts.
>
> Regarding CPU speeds, consider the label on a chip to be a guaranteed speed,
> and nothing more.
>
> All CPUs of a given model come off the same wafers and are (generally
> speaking) made the same way, then a CPU maker tests them, and speed bins
> them, and labels them with their guaranteed speed. Sometimes chips that can
> run at higher speeds reliably get labelled with a lower speed (especially
> later in the manufacturing process when most of the kinks have been worked
> out and yields are very good).
>
> So obviously a 68040 labelled as a 40Mhz model will run at 40Mhz, whereas a
> 25Mhz 040 running at 40Mhz will be luck of the draw (ignoring whether or not
> other components are also happy running at higher speeds than they are rated
> for).
This last was really my question (paranthetically yours) - that is if
the other components too are associated with the lower ratings.
note on my 475/605 and 630 models the overclockings involved moving a
resistor or two (or maybe adding one in the case of going to 40mhz).
there have been tales of video instabilities.
believe it or not there are maybe ~100 servers on the web of vintage
macs of 68k vintage. I was looking at a few the other day and getting
reinspired a bit.
>
> - Nate
>
> On Wed, Mar 4, 2009 at 11:58 PM, Brian Morris <[email protected]> wrote:
>
> > is there a meaning to HRC as opposed to just plain RC in chip letters ?
>
> > if overclocking does it help to have a cpu rated at higher speeds.
>
> > if I get a 40mhz can I overclock an originally 25mhz to 40 more
> > reliably than say a 33mhz ?
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