MiniMig with AGA

[billt]

It has to work in legacy mode of course as well, these new modes are no use unless we write a driver to support them.
/Mike

Wasn't there an old AGA driver for P96 or CGX? Even if it seemed silly back then, it may start making more sense now with this new AGA and potential addons in Minimig. OK, so maybe new modes aren't useful without drivers. So write a driver... I don't see that as a reason not to create new modes.

[tasmanian guy]

Wasn't there an old AGA driver for P96 or CGX? Even if it seemed silly back then, it may start making more sense now with this new AGA and potential addons in Minimig. OK, so maybe new modes aren't useful without drivers. So write a driver... I don't see that as a reason not to create new modes.

I believe in baby steps, minimig then came the arm processor add on.
 
If we can get minimig + AGA + more processing speed (along with being able to use a normal mouse and keyboard, with vga output that acts as a scan doubler) I am happy.
 
Leave all the other stuff for version 2, lets just get the hardware out there!

[xyzzy]

I'd like to see what happens when a team of demo coders get their hands on one.

[Hattig]

Plane mode is least efficient from a DRAM point of view. What I did with the ST is to burst read a chunk from each plane from the DRAM and hold it in a local RAM cache. I can then combine each plane how I like. The DRAM access is very efficient as it is reading 8 word burst access per plane. I wrote it to support 32 planes, and they all share one RAM block.

I didn't even know the ST had planar graphics modes. I thought it supported 16, 4 or 2 colours on screen, in a chunky format.

However planar graphics in conjunction with a fast (potentially full scanline, but actually only needs to be the optimal size of a DRAM burst access per plane) cache as you describe isn't so bad for outputting the graphics to a monitor.

[mikej]

I didn't even know the ST had planar graphics modes. I thought it supported 16, 4 or 2 colours on screen, in a chunky format.

However planar graphics in conjunction with a fast (potentially full scanline, but actually only needs to be the optimal size of a DRAM burst access per plane) cache as you describe isn't so bad for outputting the graphics to a monitor.

In the original machine the planes are interleaved in 16 bit words, so in 4 plane mode you get
     
 plane 0 |plane 1 |plane 2 |plane 3 |plane 0 | etc

but I wanted to expand this. Just messing around to play with the memory controller to be honest.
/MikeJ

[bbond007]

I believe in baby steps, minimig then came the arm processor add on.
 
If we can get minimig + AGA + more processing speed (along with being able to use a normal mouse and keyboard, with vga output that acts as a scan doubler) I am happy.
 
Leave all the other stuff for version 2, lets just get the hardware out there!

Interestingly enough, the current minimig 1.1 already runs optionally at A1200 speeds because it clocks the real 68K up to almost 40mhz. Should be interesting to see if the softcore cpu will be faster or slower...

Also should be interesting to see if the soft cpu is more or less compatible.

[logikstate]

@MikeJ

Will the cores be released as opensource when they are ready?

[warpdesign]

If youvare going to use a P96 driver, why not use a nice modern chip from ATI or Nvidia?

Who's going to write this driver ? Correct me if I'm wrong, but there's currently no Nvidia driver, and ATI drivers are closed source and PowerPC only (if you exclude Elbox hacks)...

[trekiej]

I was looking into planar graphics a while back and listening to MikeJ lets me know I am on the right track with an equation I was working on using. It seems that pixels are modified with a bit wise function. Each 16 bits are 16 pixels for the first plane, then second, etc.

[bbond007]

Who's going to write this driver ? Correct me if I'm wrong, but there's currently no Nvidia driver, and ATI drivers are closed source and PowerPC only (if you exclude Elbox hacks)...

Perhaps look at the UAE Picasso 96 driver. Maybe I'll write it.

[Linde]

Perhaps look at the UAE Picasso 96 driver. Maybe I'll write it.

Most likely, the P96 driver of UAE goes a long route through the system graphics API rather than poking at the graphics hardware directly, so I'm not so sure that that's a good source.

[bbond007]

Most likely, the P96 driver of UAE goes a long route through the system graphics API rather than poking at the graphics hardware directly, so I'm not so sure that that's a good source.

Still, that driver may be a good example of how to interface with P96.  The hardware side of things will be all new anyway.

[mikej]

@MikeJ

Will the cores be released as opensource when they are ready?

In general yes, I am a very keen on everything being open.

If there are any IP issues (I can only think of two, one being part of the ST chip set and the other part of my memory controller) I'll release that sub-module as obfuscated (scrambled) VHDL. In this way you can still recompile the chip and add new features to 99% of the code.

I intend all the code to be fully open from day one if possible, so I hope this will not be necessary.

The ARM code will also be available as are the schematics and a developer wrapper file for the FPGA which drives the various interfaces and has a standard interface to the different cores.

Best,
Mike

[Crom00]

Here is a shot of a possible case design done in SolidWorks. I don't have the exact locaton of the ports but when Iget my board I'll measure it. Paying homage to this projects Atart ST roots with the case design. If I have time I'll do a Commodore A500 style one. I have access to a RP machine so I'll print my own for sure.

[wawrzon]

@crom00:
not bad-
i always liked the st design despite never owned one. especially the gray plastic and that it had no external psu. the power cord sticking off its back, still a little better than amiga wedge cases, and ur design reflects it all. nicely unpretencious.

[Tension]

@crom00:
not bad-
i always liked the st design despite never owned one. especially the gray plastic and that it had no external psu. the power cord sticking off its back, still a little better than amiga wedge cases, and ur design reflects it all. nicely unpretencious.

Commodore got used to the C64 way of doing things.  They didnt see a problem with external PSUs.

At least the C64 &CD32 had a switch on the case.

They were cousins.