the red hill cpu guide

As marketing rather than technical considerations becomes ever more important, the once-clear distinctions between different products become blurred. Not too many years ago, the names of CPU chips made their place in the world clear.

The original Pentium-III (descrbed just above) was a quite spectacular but not uncommon example of a CPU manufacturer choosing a deliberately misleading name. The rot started in 1991 and was almost imperceptible at first. Oddly enough, while the object of the mis-naming game is usually to make your chip sound faster or more advanced than it really is, the first instance of it was the other way around: Intel needed to make the 486SX sound like it was slower than their (much more expensive) 486DX. (In those days, remember, floating-point was all but irrelevant to 95 percent of users, so the SX was every bit as good as a DX for most of us.) The "SX" suffix implied that, like the 386SX, the 486SX was slower.

In the following year Cyrix produced a sort of turbo-charged 386SX with 486-like internal design features. By rights, it was this chip that deserved to be called a "486SX" as it was a 16/32-bit hybrid 486, just as the 386SX was a 16/32-bit hybrid 386. But it became the 486SLC and a few unscrupulous manufacturers sold slug-like "486" SLC systems with 386SX performance to unwary buyers.

The much more common Cyrix 486DLC used a 386 pin-out and motherboard but delivered real 486 performance. Intel called it a "386 dressed up as a 486" but that was just sour grapes: the DLC could more than hold its own and had every right to the 486 name, as did the odd-ball IBM 486SLC.

1995 brought the 5x86 chips, and the misleading name game got more complicated. Both used a 486 pin-out and 486-style 32-bit memory addressing, and both claimed Pentium (i.e Intel 586) performance. The Cyrix 5x86 was more advanced than any 486, but less advanced than the Pentium or its AMD and Cyrix equivalents. It should really have been called a 4½86. A "5x86-100" sounded as fast as a Pentium-100 when in fact it was roughly equal to a Pentium 75. It certainly wasn't a 486, but it wasn't really a "586" either — a "586SX", maybe. The AMD 5x86 had less excuse: it was pure 486 technology all the way, and the only excuse for calling it a "5x86" was that it competed with the 100MHz Cyrix chip and the 75MHz Pentium on equal terms. And of course, as a "5x86-133" it sounded faster than either, which it wasn't.

Sold as:	But really a:	Comment:
Intel 486SX	486	"SX" had come to mean "16/32-bit hybrid", these were fully 32-bit
Cyrix 486SLC	486SX	An exact equivalent to the 386SX. Not much faster either.
Intel 486DX/4	486DX/3	The DX/2 was a clock-doubled 486; the DX/4 was not quad-clocked, only tripled
Cyrix 5x86	4½86 or 586SX	32/64-bit hybrid design, like the 16/32-bit 386SX
AMD 5x86	486DX/4 or 486DX/5	In the sense that the 100MHz clock-tripled 486 was clearly a "DX/3", these were a "DX/4". Or if you accept the tripled DX/4, then that makes these a "DX/5". Any way you look at it, clearly a 486.

Cyrix's M1 or 6x86, from December of 1995, also bent the rules but in a much more subtle way. It was more advanced than the Intel 586 (Pentium) but less advanced than the true sixth-generation chips which were to follow — "5½86" might have been fair. But it also introduced "PR rating" instead of MHz as a measure of speed-grade. It was fair to choose a name that implied superiority over the Pentium, and it was fair to call their 100MHz part a "PR-120" — but it wasn't fair to do both at the same time.

The 6x86MX was a sensible name for its successor (the M2), but halfway through its market life Cyrix introduced their MII — exactly the same chip but a brand-new name. There was only the flimsiest of technical excuses for this: its internal development name had originally been "M2". The reality was that the 6x86MX started life in competition with the Pentium MMX and "6x86MX" reflected this, but it's later versions were in competition with the Pentium II and the K6-2, so the marketing people judged "MII" more appropriate. In mitigation though, Cyrix never really tried to fool anyone that it was a new chip, and they did want to distinguish their product from the IBM 6x86MX.

AMD's K6-2 was another borderline case. It was unchanged from their K6 Classic except for the 3DNow extensions and the ability to run 100MHz bus speed. It was originally going to be called the "K6-3D" — a fair and accurate description — until AMD had a last minute change of heart. What's now known as the "K6-III" (in this original and more appropriate scheme) was going to be the "K6-2 3D".

Now we come to a more controversial example: the Celeron 266. Here the trickery wasn't in the name, it was in the number. Sure, it ran at 266MHz, but it performed like a Pentium MMX at 200MHz, or a 6x86MX at 150MHz (the PR-200) — passing this dog off as if it ran like any other 266MHz chip was a joke.

Sold as:	But really a:	Comment:
Cyrix 6x86	5½86 or M1	Not a full generation ahead of the Pentium.
Intel Celeron	Pentium-II SX	Billed as a 266, really about PR-200.
AMD K6-2	K6 3D or K6+	A borderline case.
Cyrix MII	6x86MX	New name, same old chip.
AMD K6-III	K6-2	Fair to give it a new name, but really should be K6-2.
Intel Pentium III	Pentium II SSE	New name, same even older chip
Pentium III "Coppermine"	Pentium-III	Improved design but only aluminium, not copper.
Pentium 4 2000	Pentium 4 PR1450	Huge clock speeds but very poor performance: should be PR rated.
Athlon XP 1800+	Athlon XP 1533	It was already the fastest CPU in the world — why make up the PR number?

Perhaps the most blatant example was Intel's original Pentium-III — a smoke and mirrors upgrade if ever there was one. It was really a "Pentium II with Streaming SIMD", not a new chip at all. Compare with the other two chips that introduced new multi-media instructions: the Pentium MMX and the K6-2. All three had extended instruction sets (which are of little value for non-games players, by the way). All three were manufactured on thinner wafers to reduce cost and increase clock speed. (But this is routine stuff: most chips have two or three process shrinks through their lifetime without a name change. The 6x86 and the Pentium Classic had about five each.) The Pentium MMX had twice as much cache and other detail changes and was about ten percent faster than a Pentium Classic at the same clock speed. The K6-2 had a faster bus speed and was also about ten percent faster than the K6 Classic — a rather weak claim to a new name, but arguable. But outside of the new instructions, the Pentium-III had nothing to justify its name. Oh, except a AU $420 million dollar TV campaign with the word "Internet" in it. (Yes, in case you don't remember, they really did try on the line that the P-III was "faster on the Internet". Astonishingly, many people believed it.)

Later on, the excellent new 2000 model Pentium-III was a substantially revised design, and would have deserved the Pentium-III name if they hadn't already used it. But the "Coppermine" name was misleading. It seems to have been a deliberate (and rather unethical) marketing decision — the part used aluminium conductors, just as all previous Pentiums had, and Intel were at least a year away from having copper technology up and running. The aim, presumably, was to preempt the inevitable wave of PR hype from AMD when that firm introduced copper technology in the new Dresden plant during mid-2000 — a year or more before Intel. (Copper is significantly faster, but it was very difficult to produce at that time.)

In the last year of the century came another: the "Cyrix III". Cyrix were bought out by National Semiconductor, remember, and the gutted remains were then sold at a bargain basement price to VIA. The Cyrix design team had been long since broken up and for design skills, VIA turned to IDT, buying that company too, and with it the WinChip design team. So the "Cyrix III", which debuted in a very low-key manner in mid-2000, was really a WinChip IV. It was a warmed-over IDT design, owned by VIA and manufactured by (of all people) National Semiconductor. The only thing that has anything to do with Cyrix was the name they screen printed on the top of the chip.

The name game continued, of course. Intel returned to their old Celeron philosophy when they introduced the Pentium 4. It was indeed a new chip, and the "Pentium 4 1400" did indeed run at 1400MHz — but it only performed at the same level as the old "inferior" Pentium-III 900. Similarly, the Pentium 4 1700 ran, as advertised, at 1700MHz, but could not out-perform the older, lower-clocked Pentium-III at 1200MHz, or an Athlon Thunderbird 1200 either.

AMD's response to this was to revive the old and rather unpopular PR rating. The Athlon XP family were introduced at 1333, 1400, 1466, and 1533MHz, but are sold as the 1500+, 1600+, 1700+ and 1800+. And this is truly bizarre, for the PR ratings did not accord with the equivalent clock speeds — they are very conservative. From the PR numbers, you would imagine that the Athlon XP 1700+ was roughly equal to a Pentium 4 1700. Not so! The 1466MHz Athlon XP 1700+ was equivalent to a Pentium 4 2100! (Or the newer and much improved 'Northwood' P4 at about 1900MHz.) Work that one out if you can. We can't make any sense of it.

Perhaps the most significant event in recent times has been the release of the Pentium M — Intel's specialist notebook CPU that, although they try not to mention it, is actually a souped-up Pentium-III. The Pentium M is an excellent performer: it uses very little power, easily beats Pentium 4 parts with much higher clockings, and (if you could get then as a desktop part at any sensible price) would be very interesting to match up against an Athlon XP. Intel's problem is that the firm has spent the last 10 years touting raw clockspeed as the be-all and end-all of performance, yet here is a CPU which performs brilliantly but has much lower raw clockspeed than its competition, and the boot is now on the other foot!

Both major manufacturers now seem to be committed to simply using arbitrary part numbers to describe individual parts, and are giving up quoting clockspeed numbers because they are so often meaningless. It is nice to see that even marketing departments can cotton on to the fundamental facts of life eventually.