Minimig Discussion Forum

Discussing the Open Source FPGA Amiga Project
It is currently Sun Aug 20, 2017 11:30 am

All times are UTC




Post new topic Reply to topic  [ 5 posts ] 
Author Message
 Post subject: Real display and sound specs?
PostPosted: Sun Aug 05, 2012 8:27 pm 
Offline

Joined: Tue Dec 02, 2008 9:42 am
Posts: 42
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?


Top
 Profile  
 
 Post subject: Re: Real display and sound specs?
PostPosted: Sun Aug 05, 2012 11:24 pm 
Offline

Joined: Tue Dec 13, 2011 7:48 pm
Posts: 341
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.)

_________________
~ Amiga 4000/030 ~ Amiga 1200 030/50MHz ~ Turbo Chameleon 64 ~ Altera DE1 with Minimig core ~
Details of my projects: http://retroramblings.net


Top
 Profile  
 
 Post subject: Re: Real display and sound specs?
PostPosted: Mon Aug 06, 2012 1:05 am 
Offline

Joined: Tue Dec 02, 2008 9:42 am
Posts: 42
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.


Top
 Profile  
 
 Post subject: Re: Real display and sound specs?
PostPosted: Mon Aug 06, 2012 8:02 am 
Offline

Joined: Tue Dec 13, 2011 7:48 pm
Posts: 341
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 :)

_________________
~ Amiga 4000/030 ~ Amiga 1200 030/50MHz ~ Turbo Chameleon 64 ~ Altera DE1 with Minimig core ~
Details of my projects: http://retroramblings.net


Top
 Profile  
 
 Post subject: Re: Real display and sound specs?
PostPosted: Mon Aug 06, 2012 6:20 pm 
Offline

Joined: Mon Dec 01, 2008 9:58 pm
Posts: 1568
Location: .de
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.

_________________
_____________________________
JMP $00000BED ; will guru-meditation until next morning


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
Translated by Xaphos © 2007, 2008, 2009 phpBB.fr