TT VME Bus Fix - Does it really make it faster?

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Atarian Computing
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Joined: Tue Aug 22, 2017 4:27 am

TT VME Bus Fix - Does it really make it faster?

Post by Atarian Computing »

From my blog: http://www.atariancomputing.com/blog/tt ... keitfaster

So I decided to attempt the VME Bus Fix as per Atari's rework procedure. The fix saves 1 clock cycle per transfer so it just might be faster. Before I did that, I took screenshots of two benchmarks:
IMG_0161.JPG
IMG_0161.JPG (2.58 MiB) Viewed 4736 times
IMG_0163.JPG
IMG_0163.JPG (4.39 MiB) Viewed 4736 times
I have a 2MB Mach 64. Only NVDI 5.03 and Idek's Nova drivers are loaded. Reference is the exact same setup and system sans Mach64. The Mach64 @ 1280x1024x256 colors is pretty much as fast as TT High. That says a lot. The ET4000 is faaar behind.

Here is the same setup after the VME Bus Fix. First result is vs the first screenshot above. The rest are with the same TT High reference.
IMG_0198.JPG
IMG_0198.JPG (3.51 MiB) Viewed 4736 times
IMG_0199.JPG
IMG_0199.JPG (3.62 MiB) Viewed 4736 times
IMG_0200.JPG
IMG_0200.JPG (3.43 MiB) Viewed 4736 times
So the results are pretty conclusive and somewhat expected. Wasn't expecting huge differences but discernable gains. Average results are not affected that much but looking at single tests the gains are 1-3% faster. This is with gfx card. I don't know how it saturates the VME bus. Which is why I tried 16bit color as well. I haven't installed Lightning yet, I wonder what speed differences we would see with USB file transfer.
Steve
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Re: TT VME Bus Fix - Does it really make it faster?

Post by Steve »

Very interesting. I have a 2mb Mach64 as well, so I might run a comparison bench.
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Cyprian
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Location: Poland

Re: TT VME Bus Fix - Does it really make it faster?

Post by Cyprian »

what is that "VME Bus Fix"?
Lynx I / Mega ST 1 / 7800 / Portfolio / Lynx II / Jaguar / TT030 / Mega STe / 800 XL / 1040 STe / Falcon030 / 65 XE / 520 STm / SM124 / SC1435
DDD HDD / AT Speed C16 / TF536 / SDrive / PAK68/3 / Lynx Multi Card / LDW Super 2000 / XCA12 / SkunkBoard / CosmosEx / SatanDisk / UltraSatan / USB Floppy Drive Emulator / Eiffel / SIO2PC / Crazy Dots / PAM Net
http://260ste.atari.org
Atarian Computing
Posts: 444
Joined: Tue Aug 22, 2017 4:27 am

Re: TT VME Bus Fix - Does it really make it faster?

Post by Atarian Computing »

Cyprian wrote: Sun Jul 22, 2018 11:40 am what is that "VME Bus Fix"?
It is an Atari issued rework procedure, one of several over the years to keep older TTs up to date as newer revisions had them incorporated in the motherboard.

Here is Atari's guide: http://dev-docs.exxosforum.co.uk/TT030_Board_Rework.pdf
Here is my visual guide for REV.C: https://www.exxosforum.co.uk/forum/viewt ... f=31&t=887
and REV.D: https://www.exxosforum.co.uk/forum/viewt ... f=31&t=902
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Cyprian
Posts: 386
Joined: Fri Dec 22, 2017 9:16 am
Location: Poland

Re: TT VME Bus Fix - Does it really make it faster?

Post by Cyprian »

ok thanks
Lynx I / Mega ST 1 / 7800 / Portfolio / Lynx II / Jaguar / TT030 / Mega STe / 800 XL / 1040 STe / Falcon030 / 65 XE / 520 STm / SM124 / SC1435
DDD HDD / AT Speed C16 / TF536 / SDrive / PAK68/3 / Lynx Multi Card / LDW Super 2000 / XCA12 / SkunkBoard / CosmosEx / SatanDisk / UltraSatan / USB Floppy Drive Emulator / Eiffel / SIO2PC / Crazy Dots / PAM Net
http://260ste.atari.org
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