Zorro 3 Bus Speed

[zipper]

I think it was theoretically max 133 MB/s burst speed.

[Karlos]

... probably just slowed down the stopwatch for measuring the fps... The 28 MHz clock drives the chipset and the CIAs housing the system timers. If the CPU clock doesn't change (like it wouldn't in a 4000) it appears to run faster because of the time warp.

IIRC, it was Redrumloa.

I was curious about his claim and wrote a PPC based timer that would measure a delay using GetSysTimePPC(), which is independent of the EClock. It measured (from the PPC side) EClock based delays, after calibrating for context switch overhead and such and got him to test it. It definitely seemed that it introduced a "time dilation" effect in most 68K benchmarking tools - any operation taking constant time would require fewer EClock ticks as the system clock was slowed down. Since the software assumed the rate was unchanged, this caused a corresponding increase in the reported performance.

This doesn't discount his original claim that some things got faster, but it definitely casts a question over the quantitative results.

[Zac67]

WTF? 150 MB/sec Zorro3! Wiki is full of BS!

The 150 MB/s (burst) figure comes directly from Dave Haynie. It assumes a 'perfect' implementation which Super Buster is far from.

Getting to or somewhere near this speed in any present Amiga won't be possible. The '030 bus of the motherboard and the memory bottleneck will definitely prevent it from reaching anything far beyond 20 MB/s. Many existing Z3 cards may also become problematic when raising the bus speed significantly. You can't even blame the developers - there simply is no platform to test them against.

[wawrzon]

No, not at all. Probably it'd be wise to stick at the current speed for compatibility reasons.

My intention in talking about PCI/e was that once you pick up this task you should do the job thoroughly - without adding too much complexity, PCI soft cores are around.

Step 1: You could redo the Buster, maybe speeding it up a bit, but most of all removing the bugs.

Step 2: Integrating a PCI port opens the door for replacing the daughterboard with one carrying any mix of Z3, PCI or PCIe slots, connected to the Buster PCB by a ribbon cable. Better PCI performance without messing with Z3.

Step 3: The daughterboard has yet another connector for hooking up an accelerator board directly to the PCI world. Except for the Bvision port danbeaver mentioned all other solutions require the - fast - accelerator to go over the - slow - motherboard bus to reach a - fast - PCI busboard. Obvious where the bottleneck sits.
At the same time the '030-to-PCI bridge we built into Buster starts to work the other way around, interfacing the accelerator to the motherboard, removing some complexity from accelerator design.

Step 4: Why use an expensive and hard-to-get 68060 CPU? Better take a cheap, fast and cool(!) ARM CPU with integrated PCIe and 68k emulation in firmware. You won't see a difference except that it's faster. The 5V adaption problem has already been solved with the Buster replacement.

i agree in full. actually what we are talking about is a complete new pci busboard along with z3 slots for compatibility. this board might plug into buster socket, as i assume if we remove booster as it is now we remove the bottleneck. or perhaps is there any other good place to hook up? i mean, a socket or connector most of amiga boards provide, not just some of them or some of accel cards. also an arm accel with 68k emu is what i am advocating since ever, even if x86 might currently still be better choice because of jit.