Granlunds FrankenSTein

[agranlund]

Managed to spend a little time to work on the new blitter board.
The Blitter works, and so does TOS decoding.

IDE appears to work but I really wont trust it until I tested it more.
Embarrassingly it appears that I forgot to rotate the IDE header as I moved it to the left side of the board :oops:

Hopefully I'll get a chance to start looking at getting the graphics card hooked up to it this weekend.

_20201113_233909.JPG

[agranlund]

First sign of life!


The firmware still needs a bit of work - I suspect the garbage comes from ignoring the RDY signal
Shifter/Gfxcard output is selectable from software and is using the GPO pin.

It's not going to win any beauty awards that's for sure! :lol:

et4000.JPG

That cable was not fun to make...

A very special thank you to @frank.lukas for invaluable information found on the atari-home forums!

[PhilC]

Looks good @agranlund time to scrounge some 16 bit ISA sockets then?

[agranlund]

Looks good @agranlund time to scrounge some 16 bit ISA sockets then?

The case wont be able to close with an ISA connector there, at least not with my card.
Height is at a premium where it goes under the keyboard and I had to modify both the gfxcard and the keyboard to make room.
Maybe if you found an even smaller gfxcard?

Making a new ET4000 graphicscard directly on the blitterboard itself would reduce the footprint quite a bit.
I'm not really looking at providing a product or even a user friendly solution for hooking up ET4000's internally in any machine though, I just wanted to see if I could somehow fit one in mine :)
But I'm happy to share schematics and information about the modifications I'm doing to my machine in case some of them are useful to anyone else.

For the ET4000, a far more user friendly solution is to just buy the VOFA adapter from Frank Lukas, make an opening in the case for the cables, and leave the gfxcard outside of the machine :)

[PhilC]

That looks about the going size for an et4000

[agranlund]

The firmware still needs a bit of work - I suspect the garbage comes from ignoring the RDY signal

Respecting the RDY signal did indeed do the trick. No more garbage pixels! :dualthumbup:
That ATF1504 is running out of space though so I'm going to have to swap it for a 1508.

Next up: write some kind of TSR that automatically switches to shifter output and ST-Low when launching games and demos, and then restores the state as it comes back to desktop.

[Steve]

@agranlund Could you explain this automatic internal/external graphics switching in more detail please? Is this something that could be added to the NOVA system provided by Frank Lukas? Cheers

[agranlund]

@agranlund Could you explain this automatic internal/external graphics switching in more detail please? Is this something that could be added to the NOVA system provided by Frank Lukas? Cheers

Sure!
On the hardware level it is just a 2-in-1-out VGA switcher IC. I'm using a TS5V522.
The ET4000 and Shifter are connected to this IC and I'm using the spare GPO signal to select which one of these should output to the VGA port.
In my case I also have a UBE-switch clone circuit between the shifter and the TS5V22.

To toggle the output I simply set GPO to either 1 or 0.
(It's bit 6 of YM register 14)

DSC_0811.JPG

I haven't given any thoughts to how you would accomplish this without the mods I already did (remove RF module, make custom board, modify case). I suppose you could probably cut the traces between shifter and monitor port and insert a similar type of circuit between?

Right now I just have a tiny executable in my auto folder that toggles the VGA switch to output the ET4000 after the gfxcard driver has been loaded.


For the next step, to automatically enable ST-Low and shifter when launching a game, I can't give any details yet since I don't actually know until I've done it :)

The route I'm going to explore is something like this:

- Have a textfile where I can list folders and/or exes that should trigger the autoswitch (I have all my games on F: so in my particular case that textfile would only need a single entry of "F:" to make all programs launched from my game drive trigger the autoswitch)
- Make a TSR that overrides whatever I need to override in TOS to intercept program starts (I'm assuming it's going to be pexec)

The overridden program launch would behave somewhat like this:
- If the program that is being started is not in a folder or subfolder to an entry in that textfile then do nothing and let TOS do it's thing as usual, else:
- Set GPO so shifter is being outputted
- And then the tricky part...
Now we'll need to get rid of the bios overrides that the gfxcard driver has installed and replace them with normal shifter ones.
SetScreen, Getrez, Setpalette, Setcolor, Logbase, Physbase etc are the obvious ones but I'm sure there's going to be more. Probably some LineA stuff also.
- Now jump to the original TOS program launch so the game can start
- At program exit, restore GPO to what it was before. Also restore our bios overrides we installed in that tricky part above.

Or something like that.. we'll see when we get there I suppose :)

[stephen_usher]

Or copy the gfx overrides, set up your own to a redirector shim which calls the appropriate one depending upon which output is in operation.

[Steve]

@agranlund

Are you some kind of genius?