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What came after the 486?

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Re: What came after the 486?

#131

Post by Tuna-Fish »

dspillett wrote: post #51
rasz wrote: post #14

Earlier quoted context omitted.

Things started progressing so fast in mid nineties that brand new top of the line computer was being matched in performance by low end offerings 2 years later. Lasted up to late 2000. December 1998 $85 Celeron 300A handily beating June 97 $594 Pentium 233 MMX, not to mention overclocked one matching 1998 $621-824 Pentium 2s. January 2002 $120 Duron 1300/Celeron 1300 beating 2000 $1000 Athlon 1000/Pentium 3 1000-1133…

> December 1998 $85 Celeron 300A handily beating June 97 $594 Pentium 233 MMX, not to mention overclocked one matching 1998 $621-824 Pentium 2s. Ah, I remember the days of Intel's fabs doing “too good” a job and many more chips passing tests for faster use being produced than expected. To fulfil orders for the slower chips some of these better batches were marked down and sold as slower units, so if you were lucky yo…

It wasn't just that. Mendocino wasn't a low bin, it was an entirely separate die from Pentium II. At the time, Pentium II used a 512kB off-die L2 cache, running at half cpu clock. To save on costs, Celeron 300A moved to a 128kB L2, which was integrated on the CPU die, and which ran at full cpu clock.

And it turns out that for a lot of software, a smaller but faster L2 was actually better than the bigger one. And because there were no fast products that used the Mendocino die, even the fastest of them were sold as Celerons. 300A was particularly nice because very nearly all of them could run at 450, and 100MHz FSB motherboards were widely available to pair with the fixed 4.5 multiplier of the CPU.

Re: What came after the 486?

#132

Post by p_l »

phire wrote: post #61
twoodfin wrote: post #33

Earlier quoted context omitted.

Itanium was bonkers in lots of ways—very cool in others. But this market segmentation idea just seems absolutely insane to me in a way I’ve never had anyone satisfactorily explain. It requires Intel to voluntarily destroy the commodity economics that put their CPUs on a rocket ship to domination. It’s as if they actually bought into the RISC FUD from the 1990’s that x86 was unscalable, exactly when it was taking its…

> It’s as if they actually bought into the RISC FUD from the 1990’s that x86 was unscalable, exactly when it was taking its biggest leaps. That's exactly what was happening. Though it helps to realise that this argument was taking place inside Intel around 1997. The Pentium II is only just hitting the market, it wasn't exactly obvious that x86 was right in the middle making its biggest leaps. RISC was absolutely domi…

Honestly what broke Itanium the most was the extreme market segmentation that made Itanium very expensive with no path to mass use.

Resulting in claim like "it's pretty good DSP, but hilariously overpriced".

Re: What came after the 486?

#135

Post by ghssds »

nobleach wrote: post #55

I was a poor kid building computers in the mid to late 90's. I tried everything I could NOT to use a true Pentium. My first build (coming from an upgraded Compaq 386DX) was an AMD 486 "DX4". I had a Diamond Stealth PCI VGA card and 16mb of DRAM. After that I tried a 233Mhz Cyrix 6x86. That chip was garbage. I had to run some software pentium emulation to get Cubase to run. I went 300Mhz Celeron after that. That was m…

"poor"

Re: What came after the 486?

#136

Post by phire »

squater wrote: post #17
chasil wrote: post #16

Earlier quoted context omitted.

If I am correct, the Pentium Pro was the first "out of order" design. It specialized in 32-bit code, and did not handle 16-bit code very well. The original Pentium I believe introduced a second pipeline that required a compiler to optimize for it to achieve maximum performance. AMD actually made successful CPUs based on Berkeley RISC, similar to SPARC (they used register windows). The AMD K5 had this RISC CPU at its…

Small correction, Pentium Pro was the first OoO microprocessor from Intel. Others like IBM POWER1 came earlier

I'm really not sure if POWER1 and PowerPC 603 should be counted as OoO or not.

It's certainly not the same kind of OoO. They had register renaming¹, But only enough storage for a few renamed registers. And they didn't have any kind of scheduler.

The lack of a scheduler meant execution units still executed all instructions in program order. The only way you could get out-of-order execution is when instructions went down different pipelines. A floating point instruction could finish execution before a previous integer instruction even started, but you could never execute two floating point instructions Out-of-Order. Or two memory instructions, or two integer instructions.

While the Pentium Pro had a full scheduler. Any instruction within the 40 μop reorder buffer could theoretically execute in any order, depending on when their dependencies were available.

Even on the later PowerPCs (like the 604) that could reorder instructions within an execution unit, the scheduling was still very limited. There was only a two entry reservation station in front of each execution unit, and it would pick whichever one was ready (and oldest). One entry could hold a blocked instruction for quite a while many later instructions passed it through the second entry.

And this two-entry reservation station scheme didn't even seem to work. The laster PowerPC 750 (aka G3) and 7400 (aka G4) went back to singe entry reservation stations on every execution unit except for the load-store units (which stuck with two entries).

It's not until the PowerPC 970 (aka G5) that we see a PowerPC design with substantial reordering capabilities.

¹ well on the PowerPC 603, only the FPU had register naming, but the POWER1 and all later PowerPCs had integer register renaming

Re: What came after the 486?

#137

Post by doubled112 »

geocrasher wrote: post #93

My first PC was a 286/12 with an AMD chip in it. I well remember the 486SX/2-66's and how terrible they were. I liked to say that Compaq put the "sorry" in Presario. In the late 90's, between around 96 and 98, I made good money building AMD 486 DX/4 133's. Those things were blindingly fast for the price. As I recall there was even a 150MHz variant. Still, my favorite CPU of all time remains the AMD K6/2-450. It wasn'…

I had a K6/2 back in the day. There was a Pentium 4 machine and then a refurbed HP desktop with a Phenom II X4 in it. I used that until I (perhaps finally) built a machine with a Ryzen 1700x.

I'm not sure where or why I have so many AM4 machines around, but my kids are still playing games fine on machines with a 1st and 2nd gen Ryzen in them.

I just upgraded another to a Ryzen 5 5500. I plan to get a few more years out of it.

The bang for my buck has been pretty high. I don't believe CPUs go obsolete immediately like they used to.

Re: What came after the 486?

#139

Post by hulitu »

AdamN wrote: post #43
twoodfin wrote: post #33

Earlier quoted context omitted.

Itanium was bonkers in lots of ways—very cool in others. But this market segmentation idea just seems absolutely insane to me in a way I’ve never had anyone satisfactorily explain. It requires Intel to voluntarily destroy the commodity economics that put their CPUs on a rocket ship to domination. It’s as if they actually bought into the RISC FUD from the 1990’s that x86 was unscalable, exactly when it was taking its…

They were trying to compete with Sun and IBM in the server space (SPARC and Power) and thought that they needed a totally pro architecture (which Itanium was). The baggage of 32-bit x86 would have just slowed it all down. However having an x86-64 would have confused customers in the middle. Think back then it was all about massive databases - that was where the big money was and x86 wasn't really setup for the top en…

> and thought that they needed a totally pro architecture (which Itanium was).

Was it though ? They made a new CPU from scratch, promissing to replace Alpha, PA-RISC and MIPS, but the first release was a flop.

The only "win" of Itanium that I see, is that it eliminated some competitors in low and medium end server market: MIPS and PA-RISC, with SPARC being on life support.

Re: What came after the 486?

#140

Post by hulitu »

daniel_iversen wrote: post #49
montroser wrote: post #44

I remember those Cyrix chips well. We had a little shop where we would assemble boxes to spec. And hey, a 486 is a 486, we reasoned. They were cheap, ran cool, and just about as fast as the others.

Me too, and I recall the Cyrix "Pentium-like" chips were cheaper and faster than Intel's actual Pentium chips! [1] [1] https://liam-on-linux.livejournal.com/49259.html

Cyrix 686 166 PR200 was flying in Linux.
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