Falcon without CPU but with Afterburner?

[ragnar76]

Hi there,

a couple of years ago i wrote about a Falcon with a dead cpu (https://www.atari-forum.com/viewtopic.p ... 55#p356555). Now i got my hands on an Afterburner040 and i wonder: it is is necessary to disable the old cpu, so is it possible to desolder the old cpu and run the falcon with the afterburner only?

You can find images of the cpu here:
https://theragnarbay.org/wp-content/upl ... 0_pads.jpg
https://theragnarbay.org/wp-content/upl ... 0_pins.jpg

bye
Bernd

[joska]

Yes, you can remove the old CPU if you have an Afterburner installed.

[acsi]

Hi Bernd,

My Falcon with Afterburner had pins 16 and 17 of the CPU lifted. I think from memory they need or should be grounded with a 1Mohm resister as well?

[joska]

One of the pins must be grounded to stop the CPU from accessing the bus. Not a problem if the CPU is removed.

[ragnar76]

@acsi yes, the install guide in the german atari wiki says it so too (http://wiki.newtosworld.de/Afterburner040) but a bit further it says:

Hinweis: Es kann sein das die CPU zwingend entfernt werden muß. Da manche CPUs auf Interrupte reagieren und so Probleme auf dem Bus erzeugen.

In english:

Note: It may be necessary to remove the CPU. Because some CPUs react to interrupts and cause problems on the bus.

So, i'm very confident it will work after removing the 68030 cpu and cleaning the pads. Now i have to find the software/drivers

[Rustynutt]

The photos of your "dead" cpu looks like it's either has an Eagle Sonic, Mighty Sonic or Afterburner installed before.
Do as you please, think I'd try to grind back a bit on the CPU pin that is to be grounded in an Afterburner installation before pulling the entire CPU up.

Also, look for the Afterburner Cook Book.
I have a copy of my Afterburner boot drive on CD when you get to that point. It's got a MiNT setup, NOVA Drivers, ect.

[joska]

My archive of the Afterburner mailing list is available here, you might find some useful tips there. Btw Rustynutt, it looks like the very last post on this mailing list was from you

[ragnar76]

@rustynutt
yes, the guy who sold it to me said it was running with a Afterburner but he wanted it switchable to go back to normal 030 mode for games and demos. somehow he destroyed the cpu then.

However, here at home, i dont have the equipment to desolder the cpu (and i'm not allowed to by the law of my wife ). will do this next weekend in out local hoackerspace. wish me luck!

@joska
Funny. There is a Thomas O. Kruse in your ml. He brought me to linux at that time

[Rustynutt]

Time machine, and funny part is I've not progressed

Correct me if mistaken, as long as the AB drivers are not enabled, the Falcon does run off the 030, even with the pins lifted?
Unfortunately can't boot mine now to verify, maybe Jo Even could chime in on that. Be a shame to yank the cpu if not necessary

I've never been a gamer, seems every question asked about new hardware is " dose it run mule?"

Honestly can't think of anything, other than possibly a game, the AB is incompatible with.

[sety]

However, here at home, i dont have the equipment to desolder the cpu (and i'm not allowed to by the law of my wife ). will do this next weekend in out local hoackerspace. wish me luck!

You can just get some ChipQuik and a small cheap vacuum pencil and then you can remove it with a regular soldering iron. You may want a bit of braid. The ChipQuik kit comes with everything else you need (flux etc)

[joska]

Correct me if mistaken, as long as the AB drivers are not enabled, the Falcon does run off the 030, even with the pins lifted?

It does not. The 030 is completely disabled, only the 040 is used.

[Rustynutt]

So without the drivers, it boots more or less in what Doug calls the "030" mode?
Once installed properly, they are so damn reliable and compatible, don't have the foggiest other than wish I'd never taken mine apart and sold the Falcon Rack. But that was a monster. That board is currently having a few of the IC's socketed where pins had to be lifted for the keyboard and midi clocks with the Nemesis installation. Not much more to go now, just find the time.
I'm not sure at this point if it's nostalgia or what. Having at CT60 and SV should be the cats meow, just never find time to really use it I guess.

[Rustynutt]

Was never good with an iron, and more than 20 years on, surely haven't gotten better.

[Rustynutt]

JoEven, AIRC, the CPU pin that's grounded is the lifted. Can that ground be ran to another less fragile connection?

[joska]

So without the drivers, it boots more or less in what Doug calls the "030" mode?

IIRC when the 040 starts up all caches are disabled, but I don't know anything else about this. FastRAM is not in use either, and the CPLD's are "NOP-ing" (I believe) the 030 MMU instructions in TOS so everything runs just fine, but slow.

JoEven, AIRC, the CPU pin that's grounded is the lifted. Can that ground be ran to another less fragile connection?

Short answer: No.
Long answer: With enough additional logic you can probably do it like the CT60 and not touch the 030 at all.

[ragnar76]

Piece of cake! With our SMD Rework Station, the CPU was almost falling down right away but i didnt find my vacuum pen so i had to bend the pins "slightly". The fun part was to test the pads for shortages using needle probes. Took me nearly 2 hrs. to test all the pads.

However. I havent tested the falcon so far. I've forgotten my VGA-Adapter at home

[sety]

Nice! You will need to tie BG low to get it to work without the CPU, (at least that's what I had to do with a CT60 with 68030 removed. I don't know much about AB) I managed to pick it up off U68 and just soldered a wire to the tinned perimeter thing where the shielding goes.

IMG_2677.JPG

[ragnar76]

I am curious! What is BG?. I can test the Falcon and if it's not stable I can ground BG.

[sety]

Oh, bus grant. Falcons are weird machines... It's what makes them so much fun to work on.

Combel will not allow anything on the expansion to take control of the bus unless it gets permission. If you tie BG low then combel will ignore anything other than the CPU on the expansion port.

[ragnar76]

Okay, i've build my test-setup last night, added the psu, the afterburner, a keyboard and my trackball and powered it on (for safetiness the fire extinguisher )

EqbnbIqXIAIjjmw.jpeg

and.... Nothing!

After a while i've noticed "Out ouf sync" on the display. After changing the display to a multisync i get this screen

EqbxRRGXUAEickR.jpeg

Anyone knows by chance (or Crystal ball) what could have gone wrong? What testpoints can i check with a regular multimeter? I do have access to an oscilloscope but i dont know how to use it

[mpattonm]

Did you replace&reset NVRAM? I can see it missing on one of the pictures.

[ragnar76]

You mean the image above? It's an image from sety, my U64 (the Blitter) is populated

[sety]

Anyone knows by chance (or Crystal ball) what could have gone wrong? What testpoints can i check with a regular multimeter? I do have access to an oscilloscope but i dont know how to use it

If you can get that scope going it'll be really handy, as you'll be able to see what the clocks are doing, and if everything's toggling the way it should etc. If you post a picture of the front of the scope we'll be able to guide you through using it. They might look a bit overwhelming but they're actually very easy to use.

[ragnar76]

It's a Rigol DS1054Z

[Rustynutt]

You'll be ready for one of these in the future too