TerribleFire accelerator for the QL accelerator card

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Dave
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Re: TerribleFire accelerator for the QL accelerator card

Postby Dave » Tue Dec 12, 2017 4:09 pm

XorA wrote:TerribleFire is basically the equivalent of an SGC.

Tetroid already said he was looking at a new version of SGC.

Dave Park also looked at something similar to the TerribleFire not based on the SGC design.

This stuff is easier on the Amiga because its OS is already aware of expansion buses with detectable hardware and the OS was always 32bit so it doesn't trip over with address assumptions.


Indeed we did.

If you're going to the expense of doing that, well, there's so many better things you could do. Having a 32-bit CPU that, whenever it has an access to video or the IO area has to do it as four separate 1-byte accesses, meanwhile the video capability is almost zero. As in, imagine every QL clone ever, and it only has the QL native display modes. That take up half the memory timing.

680X0 CPUs are very cheap and some are quite overclockable. The rest of the machine? That's where the dev bucks need to go.

It's such an intractible problem, Peter solved it by replacing the entire system with a FPGA. Even then, (screen depth*resolution) can have a heavy impact on performance, because of the way the QL is organized. If there was a way to put 128K or 256K of dual port VRAM on it, the change would be transformative. An instant doubling in speed, all the time, in modes 4 and 8, and up to 15x in higher modes.

And all this has to be done while maintaining compatibility.


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Re: TerribleFire accelerator for the QL accelerator card

Postby Zarchos » Tue Dec 12, 2017 4:25 pm

OK thanks.
Slightly but surely I understand more about the complexity of accelerator boards as far as the QL is concerned.


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Peter
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Re: TerribleFire accelerator for the QL accelerator card

Postby Peter » Tue Dec 12, 2017 10:28 pm

Dave wrote:It's such an intractible problem, Peter solved it by replacing the entire system with a FPGA. Even then, (screen depth*resolution) can have a heavy impact on performance, because of the way the QL is organized. If there was a way to put 128K or 256K of dual port VRAM on it, the change would be transformative.


With only 128K or 256K, even a single ported SDRAM approach seems acceptable, in case of the Q68 with 16 bit wide databus, corresponding to 4.7% or 9.4% speed loss.

But what colour depth and resolution would you choose with such small amount of VRAM?


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Peter
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Re: TerribleFire accelerator for the QL accelerator card

Postby Peter » Tue Dec 12, 2017 10:55 pm

thorsinclair wrote:The evolution of GC and SGC was the Aurora. What you may could aim to do is an Aurora plus?

Even standard Aurora available would be nice to have.

While I find the idea of an Aurora+ with SGC+ fun (I'd buy it, but not develop myself) it comes quite close to an integrated system like the Q68.

So care should be taken to give it some unique features. Just having a QL extension bus connector between CPU/RAM side and mainboard does not make it worthwile. Maybe support for the original keyboard and microdrives, or easy mounting in the QL case.


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Re: TerribleFire accelerator for the QL accelerator card

Postby Dave » Wed Dec 13, 2017 6:26 am

Q68+ with a real '030 CPU would be fun and only about $5 more in parts than the Q68.


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Peter
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Re: TerribleFire accelerator for the QL accelerator card

Postby Peter » Wed Dec 13, 2017 8:49 am

It is technically possible to re-use the existing Q68 PCB as baseboard for a different CPU, which is added by a card on the extension bus. Due to the pincount limitation, the bus would have to be redefined to a fast synchronous multiplexed bus where 32 bit address and 32 bit data are split into two 16 bit cycles each. If that imaginary CPU card gets its own memory, the SDRAM on the baseboard could be used for graphics only, eliminating the speed reduction in highcolour/highres. I was keeping this option in mind, just in case I'm not able to fully debug the Q68 CPU logic. In my case, it would have been a 68EC060, not a 68030.

I don't think $5 is realistic, even if you define a different solution than the one mentioned above. You'd still want an FPGA for video and peripherals, so you can't save much there. Also you'd need much more pins on the FPGA to attach it to the 68030 - leading toward a BGA case and a complex PCB which are expensive and difficult for hobbyist prototyping. (Zarchos: Sorry for abusing your thread ;) )


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Re: TerribleFire accelerator for the QL accelerator card

Postby Derek_Stewart » Wed Dec 13, 2017 9:04 am

Peter wrote:
thorsinclair wrote:The evolution of GC and SGC was the Aurora. What you may could aim to do is an Aurora plus?

Even standard Aurora available would be nice to have.

While I find the idea of an Aurora+ with SGC+ fun (I'd buy it, but not develop myself) it comes quite close to an integrated system like the Q68.

So care should be taken to give it some unique features. Just having a QL extension bus connector between CPU/RAM side and mainboard does not make it worthwile. Maybe support for the original keyboard and microdrives, or easy mounting in the QL case.


Hi,

I was going to make some more Aurora boards and build them into a QL case, with a Schon style keyboard.

But the lack of SGC was a little limiting.

I may go back to this when the Q68 demand has been satisfied.


Regards,

Derek
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Peter
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Re: TerribleFire accelerator for the QL accelerator card

Postby Peter » Wed Dec 13, 2017 10:10 am

Dave, by the way, it is likely that just adding cache to the Q68 would result in higher average performance than even a good 68030 system.

This is because the 68030 needs minimum 2 cycles for a primitive instruction, while the Q68 needs only one (if run from cache or fast RAM). Also, for example, the 68030 needs 28 cycles for a word-size multiplication, while the Q68 needs one cycle. Most QL code is still 68000-only, so the 68030 could not gain much from the advanced instructions.

You can also see that from the fact that even with "slow" RAM the Q68 is already somewhat faster than the SuperGoldCard, which is quite a good 32 bit 68020 design.


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Zarchos
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Re: TerribleFire accelerator for the QL accelerator card

Postby Zarchos » Wed Dec 13, 2017 3:47 pm

Peter wrote:Dave, by the way, it is likely that just adding cache to the Q68 would result in higher average performance than even a good 68030 system.

This is because the 68030 needs minimum 2 cycles for a primitive instruction, while the Q68 needs only one (if run from cache or fast RAM). Also, for example, the 68030 needs 28 cycles for a word-size multiplication, while the Q68 needs one cycle. Most QL code is still 68000-only, so the 68030 could not gain much from the advanced instructions.

You can also see that from the fact that even with "slow" RAM the Q68 is already somewhat faster than the SuperGoldCard, which is quite a good 32 bit 68020 design.


1 cycle for multiplication ?
How come ?
That is amazing ! A-M-A-Z-I-N-G TRUELY !!!!!!!!!!!!!!!!!!!
Do you imagine what it means for 3D ?
Even for 2D, it opens huge possibilities for physics and things like realtime beta spline calculations and so on ... that is a HUGE advantage. H-U-G-E. Holy cow !
What about division ? Is it just as fabulous ?
Yes I know anyway division is multiplication by inverse, and we have enough memory with the Q68 to have huge and precise table, but in case the division is also as fast, I'd like to know.

Are there other marvels in the Q68, Peter ?
Please, do not keep that hidden : all great features must be detailed.


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tofro
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Re: TerribleFire accelerator for the QL accelerator card

Postby tofro » Wed Dec 13, 2017 4:06 pm

thorsinclair wrote:The evolution of GC and SGC was the Aurora.


Hmm, no - not really.

The Aurora was the evolution of the graphics and I/O part of the original QL motherboard, without CPU and memory. Aurora can't live without either a GC or SGC as CPU/memory board and is basically a "combined Super-I/O and Graphics Card for GC or SGC".

Tobias



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