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Today, we've decided to revisit some of the worst CPUs ever built. To make it on to this list, a CPU needed to be fundamentally broken, as opposed to simply being poorly positioned or slower than expected. The annals of history are already stuffed with mediocre products that didn't quite meet expectations but weren't truly bad.
Note: Plenty of people will bring up the Pentium FDIV bug here, but the reason we didn't include it is simple: Despite being an enormous marketing failure for Intel and a huge expense, the actual bug was tiny. It impacted no one who wasn't already doing scientific computing and the scale and scope of the problem in technical terms was never estimated to be much of anything. The incident is recalled today more for the disastrous way Intel handled it than for any overarching problem in the Pentium micro-architecture.
We also include a few dishonourable mentions. These chips may not be the worst of the worst, but they ran into serious problems or failed to address key market segments. With that, here's our list of the worst CPUs ever made.
- Intel Itanium
- Intel Pentium 4 (Prescott)
- AMD Bulldozer
- Cyrix 6×86
- Cyrix MediaGX
- Texas Instruments TMS9900
Which CPUs make up your list of Worst CPUs Ever Made?
(Score: 2, Interesting) by anubi on Friday April 24 2020, @01:25AM (2 children)
Marty, I really appreciated you running this story. Like you, I learned a lot about other people's live experience with things I had read of but had never been there or done that.
During the heyday, I designed a 68000 based CPU board to replace a TI9900 design that was having parts availability issues. I briefly ( like in the order of seconds ) considered an 80286, but there was no way I was going to saddle our programmer with programming it in assembler! Ours ran wire bonders in realtime...we had to know exactly what that machine was doing and exactly how long it takes to do it. I was at the intersection of code, control systems, and inertial physics. Even the slightest variations in timing resulted in multiresonant chaos in the machinery that resulted in rejected product. It was either perfect, or it was not. And there was no way we were gonna ship anything less than perfect to our customer. A lot of small companies have that mindset.
These days, I like to use many AVR chips ( Arduino clones ) running simultaneously and Parallax Propellers to do realtime control. And still program in assembler. I still need very fine control over timing and interrupts once time critical sequences are launched. I get so damned picky over timing I even have all the processor cores clocked off the same physical crystal....to eliminate phasing artifacts and the resultant moire type artifacts they produce.
I did not like that 286. I found it too damm awkward to program in assembler and I hate keeping track of segmentation registers with a purple passion.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 2) by martyb on Tuesday April 28 2020, @01:41PM (1 child)
Glad you liked the story; thanks so much for the kind words!
You seem to have much more "close to the metal" experience than I. Oh, I'd worked a bunch with assembler way back when, but I prefer coding on top of an OS with all the conveniences their abstractions provided.
Wit is intellect, dancing.
(Score: 1) by anubi on Wednesday April 29 2020, @09:34AM
Thanks! It's an honor and privilege to exchange war stories with others in the trenches.
It takes all types. Building something like SoylentNews to me is a black art. I have my plate full with just microcontrollers. Now, those, I can play with until I know know them and their interfacing to the real world end-to-end. But get beyond C++, and I'm quickly lost. The languages seem simple enough - but it's all those little details that have me wasting way too much time barking up the wrong tree.
Thanks for all the work I've seen you putting into running these forums. For many of us, it's our main link to the other soldiers in other trenches. Fighting ignorance. Trying to build a solid public foundation to store our accumulated knowledge in.
When all is said and done, what we keep is what we share...our humanity, love, art, and science. All else rots back to the oblivion from which it came.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]