OverDRIVING the DOS Compatible Macintosh Performa
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- เผยแพร่เมื่อ 21 ก.ค. 2024
- In case you were wondering how big the difference are between the Cyrix DX2 vs the Intel DX4 Overdrive on Apples DOS compatible 68k Mac from 1995, you now have the answer!
Chapters:
00:00 Intro
00:55 About the benchmarks
01:22 Getting the baselines
05:30 Installing the DX4 Overdrive CPU
06:02 System Information
06:34 3DBench
06:50 PC Player Benchmark
07:06 DOOM
08:11 Quake
08:33 Descent
Music used in this video
Blue Intermission by Congus Bongus [ / congus-bongus ]
Fugent by Lupus Note [www.epidemicsound.com/track/c...]
#RetroComputing #MARCHintosh #Benchmarks - แนวปฏิบัติและการใช้ชีวิต
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Interesting, never heard of this 'DOS Compatible' Performa model. I had a Performa 600 back in the day, played a lot of SC2K on that! Nice video 🙂
Once had a PC back in the day with a Cyrix DX2/66 and it was clocked at 80Mhz.
Love this video, excellent experiment :) Actually been wondering this for years ;)
My first built PC was a dx4 100. What a blast from the past. Great video.
One of my PowerPC Holy Grails is to obtain an one of the Orange Micro Pentium DOS compatibility Cards. I've been very curious about the performance since I was a kid.
Would love to get my hands on one of those too! Seems like complete unobtanium tho :(
Great video again, thanks for the awesome content!
Descent
I thought someone would have already given an answer as to why the speed difference varied so much, and in some cases didn't seem to be an improvement, but nobody has that I can see, so here goes.
In that generation of CPU, there was a concept called the FSB or Front Side Bus. This is how the CPU communicated with the rest of the system, and all other things being equal, a faster FSB means it can communicate with the rest of the system faster.
The other concept relevant here is the clock multiplier. This is basically how much faster then the FSB the CPU operates internally, and THIS is where the clock speed is derived from.
This is where the 2 in DX2 and the 4 in DX4 come from.
The DX2 chips (both of them) run on a 33MHz FSB and have a x2 multiplier. So 33MHz externally to the rest of the system, doubled to 66MHz within the chip.
The DX4 chip runs on a 25MHz FSB and has a x4 multiplier, so quadrupled to 100MHz.
Importantly, the CPU needs to go through the FSB to interface with ANYTHING external to the CPU itself. That includes reading and writing to RAM, the gfx card, the HDD, literally everything.
The only time the extra speed of the DX4 100 can stretch it's legs, so to speak, is when that clock speed is more important then how fast it can communicate with the rest of the board.
For this reason, a DX2 running at 80Mhz will absolutely wipe the floor with a DX4 at 100MHz in most cases, as in that case the DX2 is running on a 40MHz FSB. I'm not sure what CPU options are available for the DOS card, but yes, in some cases, the effective speed of a DX4 100 will be SLOWER than a DX2 66.
But it really does depend on the application, how much cache there is inside the CPU, etc.
There is so much more to it than the clock speed the chip is rated at.
In the video, both chips are using the same bus speed : 33Mhz.
Curious as to see if you could run Windows 95 (or maybe something further on) on this machine with the upgraded CPU. I think it'd be neat to see.
I believe Apple officially supported Windows 95 with these DOS cards. But It’d be interesting to see if it’s possible to get Win 98 to run too!
Some Cyrix chips had a slightly faster instruction pipeline than their Intel counterparts, and lots of times were faster WINGUI Office machines, there were even GUI accelerated video cards that worked better with Cyrix chips but would fall behind in floating point intensive software.
Hey, I've been thinking about your channel recently. Noticed you haven't uploaded in 6 months. I hope you're doing well. Thanks for the high quality content.
All is good, but I've had a lot on my plate this summer, so unfortunately the channel ended up being a bit neglected :/ It's not dead yet though, and new content will arrive soon-ish!
Cheers, and thanks for reaching out!
Yes!
I think LGR did a video on this Performa (or a similar one) and I recall he mentioned that performance was worse than a PC using the same cpu so I think it has something to do with the pds slot and/or having to share graphics.
Yeah, especially the VGA chip is probably a big bottleneck in these tests.
Any cache on the pc side.
I don't think that the main bottleneck is the CPU itself, maybe it's the interface to the MAC and/or the graphics chip
Yeah, the graphics are definitely a likely suspect!
I thought the Intel Pentium Overdrive was the fastest CPU that would fit a 486 Socket.
The Pentium overdrive is a cut down P54 core in a 486 socket compatible package.
Can you try this?
For sure! I’ll try it if I ever get my hands on one.
@@OddObsolete If you use an interposer board, you can fit an AMD 5x86, but I tried it in my Performa 630 and it wouldn't boot sadly. Also, it was physically difficult to fit in the stack of interposer, CPU and heatsink. I'm not sure if I would have had more luck with another variant of the 5x86 or another interposer board that let me set the cache between write through / write back... or if it would never work.
Why would an AMD 5x86 5V upgrade Module not work?
I have no idea. Is that like the AMD equivalent of the Pentium overdrive?
@@OddObsolete It's closer to the DX4 OverDrive but clocks up to 133MHz. The 5x86 would definitely be faster than the DX4 but they're 3.45v native, so they're not drop-ins; you need the special 5v-compatible versions, which are QFP chips mounted to a PGA adapter with a built-in VRM. The Kingston Turbochip and Evergreen 586 are essentially the same thing.
@@fsfs555 @john_ace I've tried and it didn't work in my Performa 630 - I suspect it was due to the cache settings. I can't remember if my interposer (for adjusting the voltage) didn't have any jumpers for cache, I think it didn't, plus there are no comprehensive BIOS settings on the DOS card.
@@OddObsolete Its more like an improved 486 variant, but with high clockspeeds and some extras. You can get them with a 16k cache, and ones that support write through and write back. If you want to do this, learn from my mistakes, and the best one to get to ensure it fits inside the Performa would be one of the QFP package chips already soldered onto an interposer board and sold as a single thing. I bought the standard socketed CPU and a separate interposer and it didn't... really fit properly.
Please, don't make that intro to loud. I cannot play every time with the volume buttons. It's annoying.
Thanks for the feedback, I'll look over the levels!
@@OddObsolete lol to be more specific about the feedback, music was much louder than your voice, and your voice volume was very low. Thats what was wrong.