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Question about rasters and emu's

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Devilmarkus:
Hi together,
as I downloaded the new "Star Sabre 128k", I noticed, that the rasters in MODE 2 menu have been in-correct.

So I looked at JavaCPC's Z80 emulation, especially for the extra CPC-timings.

I changed a byte there from 1 to 0, and the rasters are shown correctly now.

I also made an own raster-image in MODE 1 which uses about 8 Colours.

The result is shown perfectly on a real CPC 6128 and in JavaCPC.

ALL (ALL!!!) other emulators like WinAPE, WinCPC, Caprice, CPCE95, Arnold, PCCPC etc.... cannot show this image properly.

Now my suggestion:
I think, some docs for the Z80 are not 100% exactly.

So for all Emu-coders:
Please check Z80 emulation.


This is the perfect result of my screen. 1-1 like on a real CPC.
Other emus have colour-distortions or disturbing stripes in the screen!

http://cpc-live.com/raster.dsk please check this DSK I made.
RUN"DISC" and you will see the screen.

I hope this helps to make other emulators more accurate.

If Richard reads this:
I changed in 'byte[] CPC_EXTRA_TIME' the last byte from 1 to 0.

--- Code: ---  protected static final byte[] CPC_TIME_EXTRA = {
      1, 1, 2, 5, 1, 2, 1, 1, 2, 2, 2, 0, 0, 5, 0
  }

--- End code ---
jemu.system.cpc.z80.java

Cheers,
Markus

Executioner:

--- Quote from: CPC-Live on 21:05, 08 March 09 ---If Richard reads this:
I changed in 'byte[] CPC_EXTRA_TIME' the last byte from 1 to 0.

--- Code: ---  protected static final byte[] CPC_TIME_EXTRA = {
      1, 1, 2, 5, 1, 2, 1, 1, 2, 2, 2, 0, 0, 5, 0
  }

--- End code ---

--- End quote ---

The value you changed is the Z80 interrupt acknowledge time which is added to the interrupt time on most instructions. Without this, the interrupt timing is wrong. The DSK image works on WinAPE with CRTC Type 3 (ASIC). What type of real CPC did you test it on?

Devilmarkus:
I tested it on my CPC 6128 (CRTC 1)

BTW.: With this change, also other programs work better now.
For example: the 'Camembert meeting' demo works not perfect, but is visible and playing.

'Star Sabre 128k' also has correct colour rasters now.

Devilmarkus:
Here's a screenshot of my CTM-644 with my CPC 6128 running:

Click the picture to enlarge

Gryzor:
Rather impressive :)

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