[K12OSN] i586, i686? how do I tell? (off topic)

"Terrell Prudé, Jr." microman at cmosnetworks.com
Fri Dec 24 21:19:29 UTC 2004

No problem.  Here's your cross-reference, with a little bit of history.

80386 ---> i386 (of course)
80486 ---> i486 (of course)
Pentium   ---> 80586, or i586
Pentium Pro ---> 80686 (i686)
Pentium II ---> 80686
Pentium III ---> 80686
Pentium 4 ---> "80786" ("i786")

Thus, your mobile Pentium III is an 80686 chip.

So, what the heck is going on here?


Here's the deal:  back in the 8086 days (the first really popular 16-bit 
microprocessor), Intel found that they needed more capacity to produce 
their 8088 CPU, because IBM had selected the 8088 chip for its new IBM 
Personal Computer, model 5150.  The 8088 is simply an 8086 with an 8-bit 
data bus vs. the 8086's 16-bit data bus.  Demand for 8086 and 
(especially) 8088 chips shot through the roof, as most of us 30 years 
old and up might remember.  A little outfit called AMD was thus 
contracted to make 8086 chips for Intel.  But AMD wasn't content to 
simply be a chip foundry; they wanted to make the chip better and have 
their commission go up.  :-)  So, they started improving the chip design 
and made faster versions of the 8086.  Compaq primarily used the 8086 in 
their Deskpro line.

This continued with the (short-lived) 80186, but it really became 
evident when the PC AT, with the new 6MHz 80286, came out.  AMD somehow 
wrangled intellectual property rights to sell their own versions of this 
chip!  You very soon saw AMD 80286's of 8MHz, 10MHz, 12, 16, and even 
20MHz.  Intel just couldn't keep up; their fastest 80286 ran at 12MHz.  
AMD was making a killing, but Intel had a trump card...

...the 80*3*86!  Yes, the mighty 16MHz, fully 32-bit, Intel 80386DX, 
released in 1986 and appearing first in the Compaq Deskpro 386 that same 
year, was to be the AMD '286 killer, and the '386DX is the chip on which 
ALL future Intel designs are based, up to and including today's Pentium 
4.  Yes, that's how forward-thinking Intel was with this design.  
But...AMD quickly came out with a 20MHz version of the same chip!  Then 
the MHz wars began in earnest.  Intel's fastest was the 386-33, but 
AMD's was the 386-40.   But again, Intel had a trump card...

...you guessed it, the 80486DX, which debuted at 20MHz and, before 
clock-doubling, ran at a max speed of 50MHz.  Well, AMD didn't quit, and 
the MHz war continued, which is why the clock-doubling/tripling bit was 
used in the 80486DX2-66 and DX4-100 (should really have been called 
"DX3-100" since the clock was tripled, not quadrupled) came to be.  But 
again, AMD adapted and came out with an 80486DX4-133, later called the 
5x86-P75.  AMD was constantly nailing Intel with better, faster chips.  
It was during this period that you saw the "Intel Inside" 
(dun-ding-dun-deeng!) campaign begin.

Intel decided it was trump-card time again, this time with the 80586.  
However, Intel had a small marketing problem.  As we've seen, AMD kept 
coming out with chips of the same designation, just faster, so Intel 
tried to trademark the name "80586" so that couldn't happen anymore.  
Intel found that, in the United States, you can't trademark a number.  
Uh-oh, what's Chipzilla to do?  The name "Pentium" was therefore chosen 
to indicate "fifth generation x86" technology.  As you know, the name 
Pentium was an enormous marketing success, and after Intel fixed the 
infamous "F0 0F" bug in that chip, they just took off here, both because 
of marketing and the fact that there was nothing that AMD or Cyrix at 
the time had that could touch the Pentium.  Oh, and it supported dual- 
and quad-processor configurations, too, which pleased Microsoft because 
of Windows NT.  Intel was VERY HAPPY.

But then Cyrix came out with their 6x86, a chip that you could call a 
hybrid of '586 and '686 technology; it ran hot, but it would beat the 
socks off of a Pentium.  Intel came out with their "true" 80686 chip 
just shortly before then, but they correctly recognized the massive 
brand recognition of the name Pentium and wanted to capitalize on that 
momentum.  Thus, instead of "Hexium", Intel dubbed their 80686 chip the 
"Pentium Pro" and targeted it at the high-end workstation market (see, 
it was a very expensive chip to make).  Problem:  The Pentium Pro was 
optimized for 32-bit software at the expense of 16-bit software, thus 
the Pentium (and also the Cyrix 6x86) would run 16-bit DOS/Windows 
faster than the P-Pro, but with 32-bit software like Windows NT or 
GNU/Linux, the P-Pro just annihilated everything else, even the Cyrix 
when in floating-point mode.  See, Intel actually believed Microsoft 
when the latter said that everyone would be on 32-bit software because 
of "Chicago", later officially named Windows 95, which we all know was 
delayed by two full years.  But even when it finally came out, Windows 
95 had so much 16-bit code in it that the Pentium Pro suffered in 
WinBench tests against the Pentium, and nobody ran benchmarks on Windows 
NT.  See, (almost) nobody had NT at home on their 4 and 8MB home 
computers, and GNU/Linux was still very, very rough then for non-alphageeks.

Thus, Intel robbed from the 32-bit performance to put back some 16-bit 
performance on its "consumer" grade edition of the P-Pro, which Intel 
dubbed the "Pentium II", still capitalizing on the "Pentium" brand's 
momentum.  Yes, the Pentium II is simply a somewhat de-tuned, slightly 
crippled Pentium Pro, and thus an 80686.  The Pentium III is simply a 
Pentium II on a smaller die, and with that nefarious Processor Serial 
Number nonsense included.

Just to show you how strong the Pentium brand recognition is, note the 
following.  Most of us remember when AMD introduced their terrific 
Athlon (their version of an 80786 chip), which promptly commenced to 
consistently kick the Pentium III's butt.  The Duron, which is only an 
Athlon with less L2 cache, laid equal waste to Intel's Celeron and even 
the Pentium III in some cases.  Intel was getting killed even in their 
holiest of holies, the MHz wars, plus, the '786 Athlon was and is better 
*per MHz* than Intel's '686 Pentium III (until the Tualatin version, in 
which Intel finally caught up--Tualatin PIII's are very good).  AMD 
actually beat Intel to 1GHz, thus calling for another trump card by 

...the 80786, dubbed the "Pentium 4", which debuted at 1.4GHz (1.3GHz 
for laptop versions).  That name is, as you can guess by now, entirely 
for marketing reasons; it really should be called the "Septium" or 
"Heptium" or some such, and it was never referred to publicly as an 
80786, hence the quotes in my cross-reference.  In this chip, Intel 
again robbed Peter to pay Paul, in this case "Peter" being "performance 
per MHz", and "Paul" being "MHz".  That's why Intel was able to ramp up 
the clock speed so quickly, because they detuned their chip, for exactly 
that purpose.  It was all about marketing, marketing, marketing; AMD's 
1.4GHz Athlon would just kill a 1.4GHz Pentium 4, but when the P4 got to 
1.8 MHz, then things would even out, thus AMD's "P-rating" system like 
"2400+" for their 2GHz chip.  Those not heavy into the computer industry 
buy MHz/GHz, because it's what they know.  Intel definitely won the 
battle that time.

Note, though, that Intel's again playing catch-up, this time 64-bit 
catch-up, to the "80886" from AMD, originally called the K8, and now 
better known as the Opteron and Athlon64.  Ain't competition great?  :-)


aaa at pacifier.com wrote:

>Thanks Terry,
>I see Mobile Intel Pentium III CPU -m 1200MHz.
>What I don't know is if this is an i386, i486 etc...
>Is there a cross reference somewhere?
>>Just cat /proc/cpuinfo, and you'll get what you want.  Example from my
>>multimedia thick client:
>>microman at multimedia:~$ cat /proc/cpuinfo | more
>>processor       : 0
>>vendor_id       : AuthenticAMD
>>cpu family      : 6
>>model           : 8
>>model name      : AMD Athlon(tm) XP 2400+
>>stepping        : 1
>>cpu MHz         : 2004.545
>>cache size      : 256 KB
>>fdiv_bug        : no
>>hlt_bug         : no
>>f00f_bug        : no
>>coma_bug        : no
>>fpu             : yes
>>fpu_exception   : yes
>>cpuid level     : 1
>>wp              : yes
>>flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
>>mca cmov
>>pat pse36 mmx fxsr sse syscall mmxext 3dnowext 3dnow
>>bogomips        : 3997.69
>>microman at multimedia:~$
>>BTW, yes, I think AMD rocks.  :-)
>>aaa at pacifier.com wrote:
>>>How do I tell which processor class is installed in my computer?
>>>Some RPM's   are set up for certain class of processor and I don't know
>>>which one to choose!
>>>Any cross reference tables out there?
>>>Duane Wilson

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