DSTB1 exxos first tests & experimental firmware.

Discussion and support for the DSTB1 & DFB1 boosters by BadWolf..
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Re: DSTB1 exxos first tests & experimental firmware.

Post by Badwolf »

exxos wrote: Thu May 05, 2022 2:07 pm Just a sanity check here that TOS206 does actually run from alt-ram without any crazy-ass patching ? as I was sure that PP's program which loads TOS into alt-ram did a lot of crazy patching to get it to work ?

But in this particular case I don't think there is any point in ROM running in alt-ram. The physical ROM can be accessed at 16Mhz anyway.
There's a few things here.

* Firstly, you're still running normal ROM. Don't play with AltROM.PRG until you're happy with AltRAM.PRG. AltROM.PRG is just a cool hack.

* Next, with AltROM.PRG (which we're not using), TOS isn't running from system RAM anyway.

As far as it's concerned it's running from memory at 0xE00000, just as normal. No patching required. That we allow it to be written to as well is besides the point -- we could elect not to and it would be utterly indistingishable from an external ROM chip (like yours on the ST536).

With AltROM.PRG, it's not that the system sees 4MB ST-RAM and 8MB of AltRAM and the OS is running from a reserved block within that allocation. The system only has 4MB ST-RAM and 7MB AltRAM.

You follow?

BW


PS The next evolution of AltROM, once you're happy with AltRAM, is to load the ROM image from disc instead of from phsyical ROM. This would allow you to do away with decoding logic altogether... :signhere:
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
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Re: DSTB1 exxos first tests & experimental firmware.

Post by exxos »

@Badwolf altram.prg seems fine currently. passes RAM tests.

IMG_0547.JPG
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Currently I am trying to work out why the blitter is unhappy.
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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Re: DSTB1 exxos first tests & experimental firmware.

Post by Badwolf »

exxos wrote: Thu May 05, 2022 2:41 pm @Badwolf altram.prg seems fine currently. passes RAM tests.
Cool.

So this is 'stock' (CPU on top) or slave mode? (I'm so confused -- I thought we'd gone back to stock and were looking at floppy issues on the other thread!)
Currently I am trying to work out why the blitter is unhappy.
Blitter is not allowed access to AltRAM in the stock firmware. What I believe the main problem to be is that timing (pin to pin latency) is marginal on the SDRAM controller and one more logic gate in the chain pushes it over the edge.

The key is combining altram_access_int with altram_access_ext in the SDRAM controller's .ACCESS() input.

BW
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
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FrontBench The Frontier: Elite 2 intro as a benchmark
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Re: DSTB1 exxos first tests & experimental firmware.

Post by exxos »

Badwolf wrote: Thu May 05, 2022 2:48 pm So this is 'stock' (CPU on top) or slave mode? (I'm so confused -- I thought we'd gone back to stock and were looking at floppy issues on the other thread!)
I have "shelved" the H5 setup (slave mode) for now. I am working with the "CPU in booster" now.. But I wasn't having much luck with your firmware.. Hence coming back here for the "experimental" firmware. Basically my hacked up firmware , in trying to sort the blitter out etc.
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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 ~
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Re: DSTB1 exxos first tests & experimental firmware.

Post by exxos »

Badwolf wrote: Thu May 05, 2022 2:48 pm The key is combining altram_access_int with altram_access_ext in the SDRAM controller's .ACCESS() input.
That has actually got stripped out kinda now..

Code: Select all

wire altram_access_int = (AS & AS_INT) | ENABLE | ( A[23:22] != 2'b01 && A[23:22] != 2'b10 ) ; //& rom_access
//wire altram_access_ext = AS | ENABLE | ( A[23:22] != 2'b01 && A[23:22] != 2'b10 );

//wire [3:0] REWRITE_A2320 = rom_access ? A[23:20] : 4'hB;

//& altram_access_ext
nouveau_sdram sdram(
	.CLK(RAMCLK),
	.CLK8(CLK8),
	.RST(RST),
	
	.ACCESS( altram_access_int  ) ,
	etc
I will add it back in on my next test...

Code: Select all

wire altram_access_int =  AS_INT | ENABLE | ( A[23:22] != 2'b01 && A[23:22] != 2'b10 ) ; //& rom_access
wire altram_access_ext = AS | ENABLE | ( A[23:22] != 2'b01 && A[23:22] != 2'b10 );

//wire [3:0] REWRITE_A2320 = rom_access ? A[23:20] : 4'hB;

//
nouveau_sdram sdram(
	.CLK(RAMCLK),
	.CLK8(CLK8),
	.RST(RST),
	
	.ACCESS( altram_access_int & altram_access_ext ) ,
Blitter still fine.. but I have changed other stuff as well..
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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Re: DSTB1 exxos first tests & experimental firmware.

Post by exxos »

This is working with blitter now...

IMG_0548.JPG
IMG_0548.JPG (237.36 KiB) Viewed 1540 times

Just doing a RAM test for a bit to make sure I did not break that :lol:
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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 ~
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Re: DSTB1 exxos first tests & experimental firmware.

Post by Badwolf »

exxos wrote: Thu May 05, 2022 3:17 pm This is working with blitter now...
Cool. But you thought you were here before, as well.

I refer the hon. gentleman to the reply I gave some days ago:-

https://www.exxosforum.co.uk/forum/viewt ... =30#p84015

Although, seriously, if you can get it to work reliably, that'd be a big upgrade.

BW

EDIT:

In case it's been lost in the mists of time, blitter *ALMOST* worked for me with that extra & term. However MiNT failed and certain combinations of menus showed artefacts, so it wasn't good enough to ship.
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
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FrontBench The Frontier: Elite 2 intro as a benchmark
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Re: DSTB1 exxos first tests & experimental firmware.

Post by exxos »

Badwolf wrote: Thu May 05, 2022 3:25 pm Cool. But you thought you were here before, as well.
.........
In case it's been lost in the mists of time, blitter *ALMOST* worked for me with that extra & term. However MiNT failed and certain combinations of menus showed artefacts, so it wasn't good enough to ship.
I had some intermittent RAM issues before.

I will send you my jed.. seems to work fine here with the quick tests I've done so far. But I don't have anything set up like MiNT which hammers the alt-ram.
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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 ~
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Re: DSTB1 exxos first tests & experimental firmware.

Post by exxos »

It ran GB6 fine, YAARTTT fine, load FB and :fire: :fire: :fire:

IMG_0549.JPG
IMG_0549.JPG (64.64 KiB) Viewed 1526 times


@Badwolf You don't think the clock switching is adding random timing glitches into the RAM logic do you ? 8Mhz we know isn't happy. So if a slower CPU causes problems, maybe if there are timing discrepancies in the clock that could throw it out as well.
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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Re: DSTB1 exxos first tests & experimental firmware.

Post by Badwolf »

exxos wrote: Thu May 05, 2022 3:46 pm It ran GB6 fine, YAARTTT fine, load FB and :fire: :fire: :fire:

@Badwolf You don't think the clock switching is adding random timing glitches into the RAM logic do you ? 8Mhz we know isn't happy. So if a slower CPU causes problems, maybe if there are timing discrepancies in the clock that could throw it out as well.
I couldn't rule it out, but the way the controller has been coded from the ground up is to be (relatively) clock agnostic. It's meant to react in the shortest time to stimulus and only assert DTACK when it's ready, holding the output for as long as AS remains low. The switching, if anything, should give it more time.

There are, however, a LOT of terms in the equations governing the SDRAM. I honestly just think this is one too many. The line probably isn't stable in time and the state machine gets out of whack. For you, it's FB that shits out, for me it's MiNT.

Try removing the altram_ext term from the .ACCESS() line again, and I bet the problem goes away.

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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