Clae,
What that means is that although the chip runs internally at 66 MHz, all the input and output from the rest of the board happens at 33 MHz. It was a bit naughty of Apple to advertise these as 66 MHz machines, and they stopped doing so pretty early in the run from memory.
Actually, it's the other way around. For a long time Apple reported the bus-speed as the overall speed of their computers (so the Quadra 700 was sold as a 25MHz 68040, for example, even though the internal clock on these computers runs at 50MHz).
Then Intel started advertising the, then-new, 486 CPU by touting the speed at which it ran instructions internally, not the speed at which it communicated with the external bus.
And Apple found itself selling 25MHz 68040s while Intel was advertising their 486 as running at 50MHz (and, later, 66MHz).
Apple's eventual response was to start advertising their CPUs with a dual-speed label. This didn't happen until almost the end of the 680x0-era. I believe the Quadra 630 and Quadra 605 were almost the only '040-based models to be advertised that way (the 630 was touted as running a 33/66MHz CPU; the 605, a 25/50MHz CPU).
The first PowerPCs, OTOH, were advertised in pure Intel-fasion, with the 6100/60 (for example) touting the PowerPC 601's internal clock speed and making little to no mention of the 30MHz system bus.
These days everyone advertises the internal clock speed of the CPU as if it was representative of the computer's overall speed (a little bit like using maximum RPMs to tout a car's overal performance: and just about as useful, BTW) but it was Intel that started this, basically mis-leading, practise.
FWIW, Apple was once on the side of the angels with regards monitor size as well. The AppleColor High-Resolution RGB Monitor, released in 1987 to co-incide with the appearance of the Mac II, has a 12.8" (32.5cm) viewing area, measured diagonally. It was advertised as a 13" (33cm) display.
During this same period other vendors selling monitors with 12.8" image areas (or even less, I remember displays with a 12" viewable image) routinely advertised their displays as 14" (35.5cm). They measured from one corner of the visible glass to the other, conveniently ignoring the fact that the raster didn't extend all the way to the end of said visible glass.
Apple took a serious hammering on this front. Which is why the Macintosh Color Display (the High Res RGB's successor, released in early 1992) was marketed as a 14" display, even though it's raster only ran 11.5" diagonally.
On the monitor front, back in 1997 various monitor manufacturers (including Apple) settled a California-based class action regarding mis-leading monitor sizes and offered rebates (of US$13.00) on plaintiffs' next computer purchase (having already paid US$1,500,000 into the California education system as a fine). See <http://news.com.com/2100-1023-279169.html> for more on this.
Consequent to that, companies started making the viewable image area a distinct, if smaller, part of their CRT-monitor advertising. This isn't as recalcitrant as it might seem. By the time the class-action had been won, the numbers used to describe various monitor sizes -- 15", 17", 19", 21" &C -- were more figurative than literal. People knew what a '17" monitor' looked like, and what resolutions it could comfortably display. Calling it a '15.5"' or '16"' display might have been more accurate, but not necessarily more informative.
And, with regards LCD displays, they diagonal measurements are accurate, since the viewable area and the diagonal length of a display's LCD grid are the same thing.
Hope this is vaguely diverting, if not useful.
Regards,
Brian Forte. -- Brian Forte, <mailto:[EMAIL PROTECTED]> Writer, editor, scripter, dangerous mind.
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