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Real display and sound specs?
http://minimig.net/viewtopic.php?f=4&t=510
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Author:  NorthWay [ Sun Aug 05, 2012 8:27 pm ]
Post subject:  Real display and sound specs?

I own a C-One myself (seeing Minimig fire up and play Battle Squadron was a rush like I hadn't expected at all), but no matter how much I have searched the net I can't really find any hard data on what the video and audio can do.

Sound: KHz? Bits?
Video: Resolutions? Colourbits?

I was hoping to pick up some Verilog by messing with the sources. Doubling up sound to 16 bits or 56KHz sounded (badoom-tisch!) like something small enough to try?

Author:  MMrobinsonb5 [ Sun Aug 05, 2012 11:24 pm ]
Post subject:  Re: Real display and sound specs?

NorthWay wrote:
I own a C-One myself (seeing Minimig fire up and play Battle Squadron was a rush like I hadn't expected at all), but no matter how much I have searched the net I can't really find any hard data on what the video and audio can do.


The C-one schematics will probably tell you more than anything else: http://c64upgra.de/c-one/

Quote:
Sound: KHz? Bits?


At a quick glance, it has an lc78835m DAC - so check out the specs for that?

Quote:
Video: Resolutions? Colourbits?


Video looks like a simple R2R ladder, with 16-bit (5-6-5) colour depth. The rest will be implemented in the core itself, so the maximum possible resolution depends mainly on available RAM bandwidth.

Quote:
I was hoping to pick up some Verilog by messing with the sources. Doubling up sound to 16 bits or 56KHz sounded (badoom-tisch!) like something small enough to try?


Nice ideas - the only complication with those is that sound on the Amiga requires DMA, so making a change that doubles the amount of data required is trickier than it sounds!

What might be a better first project is maybe to add a new custom chip register that does something simple like maybe double a value written to it, then progress from there. Maybe create a "hardware assist" for something that's normally very slow on the 68K processor, such as calculating a Mandelbrot set? Or JPEG or MP3 decoding.

Either way, you'll need to write some software to go along with it - but you should at least be able to see your tinkering having some effect with something as simple as peeking and poking in AMOSPro.

Another thing that could make a nice project - though I don't know enough enough about the C1 - would be to expose the SID chip registers to the Minimig core (Assuming it hasn't already been done. Again, custom software would be needed, though.)

Author:  NorthWay [ Mon Aug 06, 2012 1:05 am ]
Post subject:  Re: Real display and sound specs?

MMrobinsonb5 wrote:
lc78835m DAC

Thanks. Looks like a good one.
MMrobinsonb5 wrote:
Nice ideas - the only complication with those is that sound on the Amiga requires DMA, so making a change that doubles the amount of data required is trickier than it sounds!

I was thinking of something simpler: Bundling channels (l+l and r+r) for double frequency or depth. I'm sitting pretty waiting for some AGA version to show up that has more bandwidth "integrated" to get more fancy than that.

Author:  MMrobinsonb5 [ Mon Aug 06, 2012 8:02 am ]
Post subject:  Re: Real display and sound specs?

NorthWay wrote:
I was thinking of something simpler: Bundling channels (l+l and r+r) for double frequency or depth.


Ah - I see, in which case, yes, that should be a pretty good starting point :)

Author:  boing4000 [ Mon Aug 06, 2012 6:20 pm ]
Post subject:  Re: Real display and sound specs?

NorthWay wrote:
I was thinking of something simpler: Bundling channels (l+l and r+r) for double frequency or depth. I'm sitting pretty waiting for some AGA version to show up that has more bandwidth "integrated" to get more fancy than that.

At least the real MinimigV1 board already provide a higher chipram data bandwidth at Turbo mode of 7.1MB/s via CPU.
In Normal mode the chipram transfer speed is back to normal 3.5MB/s as in real Amiga.

This feature can be implemented in other portings too, its called "fast chip / fastchip".
It is recommended to make this fearure switchable for compatibility reasons.

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