DFB1r4 design discussion thread

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JezC
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Re: DFB1r4 design discussion thread

Post by JezC »

exxos wrote: Fri Oct 08, 2021 10:48 am I found the same with farnell :( but I will have them in my store at some point anyway. I bulk buy things these days. I've got the 84pins in my store, but they are not 3M but don't think I had any problems with them.
Ah, ok...I will wait for those to be added to the store & select some other goodies as well/at the same time.
:thumbup: :thanksblue:
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Badwolf
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Re: DFB1r4 design discussion thread

Post by Badwolf »

JezC wrote: Fri Oct 08, 2021 11:56 am Ah, ok...I will wait for those to be added to the store & select some other goodies as well/at the same time.
:thumbup: :thanksblue:
https://www.exxosforum.co.uk/atari/store2/#0225

I can confirm these are indeed 84s and definitely not 68s, oh no.

IMG_4769.jpeg
IMG_4769.jpeg (145.67 KiB) Viewed 2001 times

:lol:

BW
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
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exxos
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Re: DFB1r4 design discussion thread

Post by exxos »

Badwolf wrote: Fri Oct 08, 2021 12:25 pm I can confirm these are indeed 84s and definitely not 68s, oh no.
Yeah we know :lol: :chairsmack: I don't think 3M even manufacture brown sockets.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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Badwolf
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Re: DFB1r4 design discussion thread

Post by Badwolf »

Quick update on what's been going on with the rev 4:

I spent a couple of weeks chasing my tail on SDRAM issues. I thought I'd got it to a state where it was working and beautifully stable on a couple of occasions then woke up in the morning and it would randomly crash out, or I'd do *one particular* thing and find an error.

Then I got to a point where it would work with the HDL fitter in 'speed optimised' mode, but not in 'dentisty optimised' mode. I didn't think that was sustainable.

So I've lumped the SDRAM onto the back burner and decided to look at getting eveything else working properly in density mode, then I'll return with perhaps a ground-up SDRAM controller.

So I'm back to looking at the DSP and why it's only ever worked on one particular card.

I'm seeing the same problem with this card that I had on the last one which is I can *read* the registers well, but can't write to them. I had one interesting discovery that the 'dspdump.tos' program (I do not remember from where I aquired it) read gibberish whereas my own probes read correctly. This suggested some difference in timing, or on what preceeded the DSP call had an effect.

Gating DTACKx to the clock fixed that, but *still* couldn't write. This very much leads me to think timing is absolutely the key to DSP access, which I can't quite understand from looking at the GAL equations and DSP documentation, but fair enough.

So I'm going to do some experimentation with a Terriblefire style clock derivation module to see if I can pre-empt the motherboard clock a fraction.

Anyway, what a PITA this hardware business is!

BW
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
Steve
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Re: DFB1r4 design discussion thread

Post by Steve »

@Badwolf It must be a little frustrating knowing that previously in the past with older accelerators ~(ct60,63,e) these problems were worked out and understood, but never documented? (question mark because I don't know, also when people have re-produced the ct60e, ie; willy, would that mean he would understand these issues you're facing?)
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Badwolf
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Re: DFB1r4 design discussion thread

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Steve wrote: Tue Oct 19, 2021 12:02 pm @Badwolf It must be a little frustrating knowing that previously in the past with older accelerators ~(ct60,63,e) these problems were worked out and understood, but never documented? (question mark because I don't know, also when people have re-produced the ct60e, ie; willy, would that mean he would understand these issues you're facing?)
Possibly encountered and fixed. Possibly never occurred because of fundamentally different design principles or good fortune (r3 had the good fortune that it just worked, for example). The SDRAM issue is almost certainly because I clock switch. If, for example, the CT2 didn't clock switch but was fully asynchronous it would probably never have had my particular method of failure.

I'm just trying to get a baseline configuration that works in the important areas and can be tweaked over time. Then I'll just publish what I have, state where the limits currently are and perhaps someone else building one will be able to improve on speed or compatibility or whatever in the firmware.

I think FPU can be left as optional if I can't make it work, but no-one wants a Falcon booster that can't use the DSP! Equally, If the SDRAM has to run at 10MB/s rather than the 24MB/s I've had it up to, sobeit. We know it can be improved down the line.

The basics, though, are an arseache! :roll:

BW
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
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exxos
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Re: DFB1r4 design discussion thread

Post by exxos »

Badwolf wrote: Tue Oct 19, 2021 12:54 pm The basics, though, are an arseache! :roll:
Indeed they are! then on that monumental day when you have it all working perfectly, someone else tries it in their machine, and it does not boot up or even tried to. Then you have to go back to square one and start all over again! :lol: :hide:
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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Badwolf
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Re: DFB1r4 design discussion thread

Post by Badwolf »

exxos wrote: Tue Oct 19, 2021 1:02 pm
Badwolf wrote: Tue Oct 19, 2021 12:54 pm The basics, though, are an arseache! :roll:
Indeed they are! then on that monumental day when you have it all working perfectly, someone else tries it in their machine, and it does not boot up or even tried to. Then you have to go back to square one and start all over again! :lol: :hide:
Ha! But that's where the most cunning part of my plan comes to my rescue: if it's working for me and I'm not trying to make money off it, it'll be left as an exercise for the reader. ;)

BW
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
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JezC
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Re: DFB1r4 design discussion thread

Post by JezC »

Badwolf wrote: Tue Oct 19, 2021 3:11 pm Ha! But that's where the most cunning part of my plan comes to my rescue: if it's working for me and I'm not trying to make money off it, it'll be left as an exercise for the reader. ;)

BW
Hmm, maybe the experiences of @terriblefire suggest that others might not fall in line with your expectations! :lol: :roll:

I'd be game to try it on my Falcon at some point & see if/how well it works on a relatively stock example (RAM is upped to 14MB but it's not had many other upgrades performed...just a few of the many & varied "fixes"...) ;)
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Badwolf
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Re: DFB1r4 design discussion thread

Post by Badwolf »

JezC wrote: Tue Oct 19, 2021 3:24 pm Hmm, maybe the experiences of @terriblefire suggest that others might not fall in line with your expectations! :lol: :roll:
Aha. the difference there is that Stephen's demonstrably the best person to fix HDL issues with the TF range. I have no qualms in admitting I'm not! :D
I'd be game to try it on my Falcon at some point & see if/how well it works on a relatively stock example (RAM is upped to 14MB but it's not had many other upgrades performed...just a few of the many & varied "fixes"...) ;)
Whereabouts are you & do you have a PGA 030 & a few 30-50MHz oscilaltors kicking around? I could send you the final iteration of the rev3b for testing if you fancy. It needs the PSU to be unseated in a clever measure to stop you hanging on to it too long :lol:

Would only really be a go/no-go, though, as there's no more dev going on on that firmware but it would be nice to get a feeler for the level of specificity of these boards to my Falcon.

BW
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
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