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Author Topic: Classic Bus overclocking?  (Read 988 times)

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Offline QuikSanzTopic starter

Classic Bus overclocking?
« on: September 29, 2016, 10:36:20 PM »
I'm curious, Can a ZII bus be doubled if if not using a Toaster. What may be the pitfalls of this. There must be some way to increase bandwidth to give lets say a Vampire better performance. A graphics card could benefit.

Chris
 

Offline Oldsmobile_Mike

Re: Classic Bus overclocking?
« Reply #1 on: September 29, 2016, 11:08:27 PM »
Quote from: QuikSanz;814612
I'm curious, Can a ZII bus be doubled if if not using a Toaster. What may be the pitfalls of this. There must be some way to increase bandwidth to give lets say a Vampire better performance. A graphics card could benefit.

Chris

Vampire sits in the CPU slot on an A2000, or in the CPU socket if you can cram it underneath the drive sled.  It doesn't use a Zorro II slot.

Don't know about overclocking the bus, I think you're hitting limitations on the old Buster chip in the A2K (as well as probably numerous other components); it never had any revisions or updates like the A3K/A4K Buster chip did for improved performance.  :(

See pic of Vampire installed in A2000 that I copied off Google+ a few days ago:
« Last Edit: September 29, 2016, 11:11:56 PM by Oldsmobile_Mike »
Amiga 500: 2MB Chip|16MB Fast|30MHz 68030+68882|3.9|Indivision ECS|GVP A500HD+|Mechware card reader + 8GB CF|Cocolino|SCSI DVD-RAM
Amiga 2000: 2MB Chip|136MB Fast|50MHz 68060|3.9|Indivision ECS + GVP Spectrum|Mechware card reader + 8GB CF|AD516|X-Surf 100|RapidRoad|Cocolino|SCSI CD-RW
 Amiga videos and other misc. stuff at https://www.youtube.com/CompTechMike/videos
 

Offline QuikSanzTopic starter

Re: Classic Bus overclocking?
« Reply #2 on: September 29, 2016, 11:21:15 PM »
I was thinking the rest of the chips may not handle this but this could reduce the "bottleneck" if it can be done.
 

Offline Oldsmobile_Mike

Re: Classic Bus overclocking?
« Reply #3 on: September 29, 2016, 11:27:21 PM »
Quote from: QuikSanz;814615
I was thinking the rest of the chips may not handle this but this could reduce the "bottleneck" if it can be done.

Pretty sure you'd get better performance using the onboard video of the Vampire board than any Zorro II graphics card.  Zorro II slots are still useful for legacy SCSI boards/peripherals, sound cards, networking, etc., though.  ;)
Amiga 500: 2MB Chip|16MB Fast|30MHz 68030+68882|3.9|Indivision ECS|GVP A500HD+|Mechware card reader + 8GB CF|Cocolino|SCSI DVD-RAM
Amiga 2000: 2MB Chip|136MB Fast|50MHz 68060|3.9|Indivision ECS + GVP Spectrum|Mechware card reader + 8GB CF|AD516|X-Surf 100|RapidRoad|Cocolino|SCSI CD-RW
 Amiga videos and other misc. stuff at https://www.youtube.com/CompTechMike/videos
 

Offline QuikSanzTopic starter

Re: Classic Bus overclocking?
« Reply #4 on: September 29, 2016, 11:54:08 PM »
Quote from: Oldsmobile_Mike;814617
Pretty sure you'd get better performance using the onboard video of the Vampire board than any Zorro II graphics card.  Zorro II slots are still useful for legacy SCSI boards/peripherals, sound cards, networking, etc., though.  ;)


If you have A USB card, sound card and net card in it the bus is waiting sometimes. forget the graphics card.
 

Offline Gulliver

Re: Classic Bus overclocking?
« Reply #5 on: September 30, 2016, 02:33:35 AM »
Yes, the bus can be overclocked but then you would face a few incompatibilities with some Zorro II cards that rely on this old timing.

Just to name a few examples:

-The Elbox Winner Zorro IV busboard (a Zorro II busboard) had a fast Zorro II mode  on some slots. The CyberVision 64/3D cards that were manufactured by DCE (not Phase 5) can take advantage of this feature and also the famous Deneb USB+flash rom card.

-The MacroSystem´s DraCo has five Zorro II slots that operate at twice the speed of the traditional Amiga Zorro II slots and can make use of most of the Zorro II cards that were made.

So yes, it can be done.
« Last Edit: September 30, 2016, 02:36:50 AM by Gulliver »
 

Offline psxphill

Re: Classic Bus overclocking?
« Reply #6 on: September 30, 2016, 07:22:19 AM »
Quote from: Gulliver;814629
-The MacroSystem´s DraCo has five Zorro II slots that operate at twice the speed of the traditional Amiga Zorro II slots and can make use of most of the Zorro II cards that were made.

So yes, it can be done.


Running zorro 2 at double the speed would involve doubling the speed of dma as well, which would also include fast ram on the cpu bus. By the time the double speed clock has spread that far round the A2000, you're running the risk of having to do something special to make it avoid hitting the cia/agnus/paula etc. You may hit problems with buster or the way the motherboard is designed. The former could be solved by creating a new buster chip, the later would require something like an "a2000 reloaded".

The draco just proves that you won't have too many problems with the cards.
 

Offline utri007

Re: Classic Bus overclocking?
« Reply #7 on: September 30, 2016, 08:52:37 AM »
This is interesting.

Would it be possible to oveclock zorro bus without affecting amiga's mobo / custom chips?

Overclocking zorro bus would have 1:1 effect for a speed of rtg graphics. 3.5mb speed of zorro II is major bottleneck. Drago's zorro is not 2x faster. Speed is about a 4.5mb tells google.
ACube Sam 440ep Flex 800mhz, 1gb ram and 240gb hd and OS4.1FE
A1200 Micronic tower, OS3.9, Apollo 060 66mhz, xPert Merlin, Delfina Lite and Micronic Scandy, 500Gb hd, 66mb ram, DVD-burner and WLAN.
A1200 desktop, OS3.9, Blizzard 060 66mhz, 66mb ram, Ide Fix Express with 160Gb HD and WLAN
A500 OS2.1, GVP+HD8 with 4mb ram, 1mb chip ram and 4gb HD
Commodore CDTV KS3.1, 1mb chip, 4mb fast ram and IDE HD
 

Offline CPG

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Re: Classic Bus overclocking?
« Reply #8 on: September 30, 2016, 11:58:13 AM »
FWIW, there's some Zorro-II hacks for A3000/4000 super busters:

http://www.amibay.com/showthread.php?18537-SuperBuster-Zorro2-Speedup-Mod
 

Offline Gulliver

Re: Classic Bus overclocking?
« Reply #9 on: September 30, 2016, 12:55:54 PM »
Quote from: utri007;814635
Drago's zorro is not 2x faster. Speed is about a 4.5mb tells google.


You should not always believe what Google tells you.
I have two DraCos at home and Zorro II slots can be run twice as fast. Of course this depends on the particular card you are using, because the card itself may be the bottleneck. :)
 

Offline QuikSanzTopic starter

Re: Classic Bus overclocking?
« Reply #10 on: September 30, 2016, 08:34:57 PM »
Hmm, Would be interesting to have a switch to toggle the speed and check it out for software and card compatibility. If some things are picky you could leave it as a turbo button.
 

Offline SpeedGeek

Re: Classic Bus overclocking?
« Reply #11 on: October 01, 2016, 02:34:04 PM »
Quote from: CPG;814638
FWIW, there's some Zorro-II hacks for A3000/4000 super busters:

http://www.amibay.com/showthread.php?18537-SuperBuster-Zorro2-Speedup-Mod

The above hack was done to get Zorro-II performance back to normal because Super Buster is a downgrade for Zorro-II users.

BTW, there are very few Zorro-II cards which could support a 2x overclock and most will fail without some extra logic to add wait states to a Zorro-II cycle.
 

Offline psxphill

Re: Classic Bus overclocking?
« Reply #12 on: October 01, 2016, 10:16:47 PM »
Quote from: SpeedGeek;814701
BTW, there are very few Zorro-II cards which could support a 2x overclock and most will fail without some extra logic to add wait states to a Zorro-II cycle.


Did you ever look at running zorro-iii cycles on an a2000?
 

Offline SpeedGeek

Re: Classic Bus overclocking?
« Reply #13 on: October 03, 2016, 04:08:26 PM »
Quote from: psxphill;814724
Did you ever look at running zorro-iii cycles on an a2000?

No, the Zorro II bus is a 68000 protocol (24/16 bit) bus and Zorro III is a proprietary (32/32 bit) bus.

If you want to design a new GBA2000 mobo with a base 68030 CPU module then you could add Zorro III support but Commodore made the A3000 because it was cheaper than an upgraded A2500.
 

Offline Oldsmobile_Mike

Re: Classic Bus overclocking?
« Reply #14 on: October 03, 2016, 06:12:43 PM »
Quote from: SpeedGeek;814701
because Super Buster is a downgrade for Zorro-II users.

Out of idle curiosity, how is it a downgrade?  Is it because of all the DMA issues in the various revisions of the chip?
Amiga 500: 2MB Chip|16MB Fast|30MHz 68030+68882|3.9|Indivision ECS|GVP A500HD+|Mechware card reader + 8GB CF|Cocolino|SCSI DVD-RAM
Amiga 2000: 2MB Chip|136MB Fast|50MHz 68060|3.9|Indivision ECS + GVP Spectrum|Mechware card reader + 8GB CF|AD516|X-Surf 100|RapidRoad|Cocolino|SCSI CD-RW
 Amiga videos and other misc. stuff at https://www.youtube.com/CompTechMike/videos