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General Category => Emulators => Topic started by: Devilmarkus on 17:20, 24 June 09

Title: Question about CRTC register 1
Post by: Devilmarkus on 17:20, 24 June 09
Hi together,
while I was coding on JavaCPC's CRTC emulation, i found some problems with "Backtro" demo.
(http://cpc-live.com/backtro.png)

I checked every CRTC register and figured this out:
- Backtro demo sets Register 1 to &BD

So i tried this (out &bc00,1:out &bd00,&bd) on several emulators, and on my CPC 6128...

Result was totally different...

Winape, WinCPC, and Arnold show this result:
(http://cpc-live.com/winape1.png)

JavaCPC shown this result:
(http://cpc-live.com/javacpc1.png)

AND!!! my CPC 6128 looked like:
(http://cpc-live.com/realcpc.png)

After some help from Kevin, I fixed JavaCPC's register 1, too, so Backtro demo works now...
(http://cpc-live.com/backtro3.png)

Question is now:
Why do emulators show a different result here, than my CPC 6128? (CRTC 1)

I set the border to red to make it visible.
Title: Re: Question about CRTC register 1
Post by: Executioner on 05:43, 25 June 09
Quote from: CPC-Live on 17:20, 24 June 09
Question is now:
Why do emulators show a different result here, than my CPC 6128? (CRTC 1)

I set the border to red to make it visible.

Not sure, did you try this with different CRTC types?
Title: Re: Question about CRTC register 1
Post by: Devilmarkus on 10:34, 25 June 09
Quote from: Executioner on 05:43, 25 June 09
Not sure, did you try this with different CRTC types?

Yes, I tried this with all possible CRTC configurations in Arnold and WinApe.
It seems to be CRTC independent.

I also wanted to try this on my 464, but it also has CRTC 1.
Title: Re: Question about CRTC register 1
Post by: Gryzor on 10:25, 26 June 09
So what emu does it run on perfectly? Because I'm pretty sure I've ran this in the past...
Title: Re: Question about CRTC register 1
Post by: Executioner on 07:37, 30 June 09
Markus, how did you get the screenshot from your real CPC? Is it exactly as it appears?
Title: Re: Question about CRTC register 1
Post by: Devilmarkus on 09:27, 30 June 09
Quote from: Executioner on 07:37, 30 June 09
Markus, how did you get the screenshot from your real CPC? Is it exactly as it appears?

Sorry, the screenshot is not 100% pixel-exact! (I modified WinApe screenshot using graphic program)
But it shows, 'how' the screen looks like on CPC 6128.
Do you see different result on your CPC/CPC+?

BTW.: Once I wrote, that "Preview 3" (hitech) demo crashes on WinApe.
I can tell you, why this happens.
It crashes, when printer output is enabled.
(I had the same problem in JavaCPC, so I modified the port-range for printer output)

(http://cpc-live.com/hitech3.png)

To explain:
JavaCPC uses a function like this:
     if (Switches.Printer)
         if (((port & 0x1000) == 0) && ((value & 0x80) != 0)){


To make sure, that this port is not reached by some funny applications, I made this:
     if (Switches.Printer)
         if (port > 0xef30 && port < 0xef3f)
         if (((port & 0x1000) == 0) && ((value & 0x80) != 0)){


Not the niciest method, but it works  ;D
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