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| Author | I was reading a debate of 68040 vs 486 (Read 47224 times) | ||||||||||||||||||||||||||||||||||||||||||||||||||
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ShinobiKenobi
256 MB  Posts: 362 System 7 fan 
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on: February 19, 2025, 22:15
And this post caught my eye (modern browser needed) Do any of you have a Quadra 800 AND a 950 in order to do a comparison? I always thought that higher model numbers meant an improved Mac, but maybe not? Anyway, it's an interesting discussion. Why would they make a newer model with a lower model number? |
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68040
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512 MB Posts: 950 68k - thy kingdom come, thy will be done !
Reply #1 on: February 20, 2025, 01:21
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When Intel first introduced the i386 they found that many corporate customers resented the need to throw away their old chip sets in favor of Intel's new line and so they brought out the i386SX. That CPU was basically a crippled 386, in that it allowed for the use of older, already established and thus cheaper chip sets (the microchips required to work alongside the CPU to handle the "minor" task of controlling peripherals). Back in them days designing a motherboard was a huge investment, specially for smaller manufacturers, as CAD hadn't really taken off yet and there were still an awful lot of manual steps involved. So once you had a successful design, you tried to keep it as long as possible, even at the expense of performance. For the last thing you wanted was to sell to your end customers an expensive CPU, embedded into a flawed motherboard. Also, it was the height of the PC wars and specially customers of scale (administrative headquarters, franchise chains and the like) began penny pinching when buying new PCs. IBM had fleeced a lot of their customers with overpriced 80286 machines and Big Blue was about to find out, that that nasty trick only worked once. People wanted choices so Intel decided to give it to them. They later repeated this feat with the i486SX. Likewise in the Server world Intel brought out a whole variety of CPUs, for the "big guns". The Xeon line for example is designed for heavy client/server usage. But even there Intel discovered that not all customers wanted to pay the big bucks for the big FLOPs. So they ended up supplementing the Xeon collection with less powerful but more affordable versions. And that is how it usually goes: A chip manufacturer overestimates what the market is willing to pay and then has to adjust his line of (G/C)PUs accordingly. Last not least, long established lines of CPUs often got boosted with custom developed extensions (-> overclocking). Nowadays not many systems will allow you to do that. But back in them days of gore and glory, we used to inject our custom builds with enough cooling liquid to freeze an aircraft carrier for eternity.  Naturally once you upgraded to a new CPU your custom built no longer fit and you got thrown back to the speed the manufacturer intended you to run on,
Last Edit: February 20, 2025, 01:23 by 68040
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lauland
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512 MB Posts: 674 Symtes 7 Mewconer!
Reply #2 on: February 20, 2025, 04:17
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I'd not call the 386sx "crippled" but more a strategic stopgap move. It was a real 386, 32-bit inside, but with a 16 bit data bus...and less than 32-bit address bus. This allowed designs that would've used the 286 (fully 16-bit) to run 32-bit code. It was extremely popular for that reason. Apple did similar things with some things, hardware-wise, with many Performas like the 6200 series, the PowerBook 5300, etc, which forced their PowerPCs, which normally use a 64-bit data bus to run on a motherboard and use a chipset designed for 32-bits...to save money and time. (PowerPCs are 32-bit processors, but their data bus reads from their caches and memory 64-bits at a time). I believe the Quadra 900 (and 950?) came out BEFORE the others, and although larger and more slots, actually had less advanced features than the 700/800. I'd have to look up what exactly those are, but am on a very old mac right now so can't browse https... I didn't read the Google Group discussion...sorry TL;DR, but figure it is probably full of the usual "MINE IS FASTER THAN YOURS" and Intel vs Motorola religious arguments that were rampant back in the day...or RISC vs CISC...and these days ARM vs Intel. It's always extremely hard to separate the wheat from the chaff in these kinds of arguments because too many people have agendas, defending their purchases and/or favorite team, exactly like sports or religion. One thing it probably covers, if you're comparing '040's and 468's, is that the '040 runs internally at twice the speed of the clock crystal used, so should always be compared to the 486DX2, which did the same trick. This kind of thing became the norm and extremely few cpus these days don't multiply their external clock. Intel at the time would brand their chips at the internal speed, but Motorola didn't. So technically, those 25 mhz 040's run at 50 mhz. CORRECTION: Wanted to be sure I was right about the clock thing...turns out the full story is way more complicated. It looks like 040's may require an EXTERNAL clock at twice their normal rate, and halves it...mostly?!? So, a "25 mhz" chip requires a 50 mhz clock. Internally, from what I can find, most of the chip runs at the slower rate, but "some arithmetic" is done at the faster rate. ¯\_(ツ)_/¯
Last Edit: February 20, 2025, 05:22 by lauland
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ovalking
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128 MB Posts: 199
Reply #3 on: February 20, 2025, 15:21
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>Quadra 800 AND a 950 I didn't read the article, but have used both. Although these Macs were both 33MHz 68040s the 800 came out about a year later, was a slightly more modern design (internally and externally), and a fair bit cheaper. 9xx(x) series tended to be top of the range enormous towers. 8xx(x) series tended to be well specced normal size towers. Must check the old 800 still works some day soon...
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68040
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512 MB Posts: 950 68k - thy kingdom come, thy will be done !
Reply #4 on: February 20, 2025, 16:12
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@laulang - well, as an IT engineer and software designer I call a 32bit CPU with a 16bit data bus and a not-quite-there-yet address bus "crippled". I grant you that this "amputation" helped manufacturers sell countless 80286 designed motherboards that would have otherwise taken their well deserved trip to the recycling plant. And yes, it was popular for just that reason. But sugar laden coke was also more popular than unsweetened fruit juice. Didn't make it any healthier though. The 80386SX was a step backwards. It served the bottom line, but not technological progress.
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Bolkonskij
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Administrator 1024 MB  Posts: 2023
Reply #5 on: February 20, 2025, 16:32
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I have absolutely no clue about Intel processors and so better hush up on the technical stuff (though enjoy the discussion chaps!) but my thought reading was along the lines of "Given the prices of new hardware at the time, serving the bottom line was actually a very valid reason." A lot of business customers had probably a very focussed need for something (e.g. running a custom-tailored text processor) and didn't need raw power beyond what a 286 CPU could deliver. Seems like this was a smart move from a marketing perspective. Quote from: 68040 IBM had fleeced a lot of their customers with overpriced 80286 machines and Big Blue was about to find out, that that nasty trick only worked once. It's easy to forget how *blazing fast* progress was in those days. Every year was a big leap forward in processing power. Those overpriced machines had quickly become obsolete and if you think about it, it's crazy how much investment was needed by organizations to keep their IT hardware "current". Stuff that costed 10,000 $ once became "worthless" only 2-3 years down the road.
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cballero
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1024 MB Posts: 1176 System 7, today and forever
Reply #6 on: February 20, 2025, 17:26
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Quote from: Bolkonskij Those overpriced machines had quickly become obsolete and if you think about it, it's crazy how much investment was needed by organizations to keep their IT hardware "current". Stuff that costed 10,000 $ once became "worthless" only 2-3 years down the road.
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ShinobiKenobi
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256 MB Posts: 362 System 7 fan
Reply #7 on: February 22, 2025, 11:41
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I'm really curious if the 800 is actually faster, and how much faster it is compared to the 950? So that if I ever get rich I can get the faster one LOL
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lauland
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512 MB Posts: 674 Symtes 7 Mewconer!
Reply #8 on: February 22, 2025, 18:26
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Looking at articles like this one, and many others: https://lowendmac.com/1993/quadra-800/ (modern browse) I think it is confirmed that the 800 IS definitely "faster" than the 950, the question would only be "how much?". That article mentions memory interleaving, faster scsi, and accelerated internal video. I think side by side benchmarks of each of those sub-systems would show, and be fascinating, but I was unable to find one.
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MTT
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256 MB Posts: 394 SSW7 Oldtimer
Reply #9 on: February 23, 2025, 00:05
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I wouldn't know about the % speed increases talked about in that 1993 usenet scraping, but the Q800 would be the faster Mac of the two. Simply because the Q950 is based on the earlier Q900 form factor, it has the same architecture as the Q900 except for an upgraded '040 66MHz CPU, which is also the same as found in the Q800. The speed difference is down to the faster RAM that the Q800 has on board, which is 72 pin SIMMs @ min speed 60ns, opposed to the Q950's older and slower 30 pin SIMM RAM @ min speed 80ns. Another factor in speed differences here, is the interleaved RAM of the Q800 which gains an additional 10% speed increase over the non-interleaved RAM that the Q950 has on board. A more modern motherboard design and on board chipsets may also contribute to the Q800 speed increases, but I wouldn't know about that. Just guessing there as an additional possibility. Of interest, but not related to speed, is the number of 30 pin SIMMs you would need to get the Q950 up to it's maximum of 256MBs. These SIMMs need to be installed in sets of 4. To get up to that max, it would take 16 x 16MB 30 pin SIMMs, which in 2025+ might not be an easy task to procure. The Q950 must have been a solid workhorse back in the day, as it's production run lasted from May 1992 to Oct 1995, whereas the Q800 lasted only 1 year from Feb 1993 to Mar 1994. The introduction of Power Macs around that time would have signaled their EOL. Of the two models, if I was to choose one, it would be the Q800. Both are towers (which I like) but the Q800 takes up less of a footprint and would be easier to lug around, coming in at approx. 11Kgs as opposed to the Q950's approx. 17kgs. Plus the faster RAM and probably easier to source 72 pin SIMMs. The negatives here for me are the NUBUS and 1 PDS slots both share. Nothing wrong with either, but finding a decent video card for either of those slot types would be a task. On board video is 1MB for the Q950 and 512Kb for the Q800, so the Q950 is a bit better off here, but for me this is not something I could live with for long. It would all boil down to how specced up either were when finding one for sale somewhere. Info sources: Apple Spec Database and Newer Technology's GURU
Last Edit: February 23, 2025, 00:08 by MTT
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ShinobiKenobi
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256 MB Posts: 362 System 7 fan
Reply #10 on: February 23, 2025, 06:56
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Thanks for all the information! That's really interesting. I love to read all your expertise and experience.
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68040
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512 MB Posts: 950 68k - thy kingdom come, thy will be done !
Reply #11 on: February 23, 2025, 16:01
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You want to know more about this never ending battle between technical sanity and the money grabbing marketing department, read the memoirs of Dilbert vs. the pointy haired Boss.
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ShinobiKenobi
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256 MB Posts: 362 System 7 fan
Reply #12 on: February 24, 2025, 04:16
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Dilbert is awesome.
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