KC compact emulator!?

[GUNHED]

Hi there! 

Is there any KC compact emulator?

It seems the the KC compact sometimes shows different color on screen compared to the CPC - while using the same hardware color value.

On CPC: black, becomes on KCc: ice-brigth-blue   And sometimes it works 

Any ideas please???



The attached picture shall have black as border and background, but it doesn't work.

[Jean-Marie]

According to the wiki page, there are Java CPC desktop & Arnold.

[Benedikt]

Have you verified that the software sets a valid color value?
The KC compact uses an EPROM to translate the 5 bit value for the 27 CPC colors to 6 bit RGB.
I don't know whether that EPROM contains the "right" values for color indices 27 to 31.

[GUNHED]

Have you verified that the software sets a valid color value?
The KC compact uses an EPROM to translate the 5 bit value for the 27 CPC colors to 6 bit RGB.
I don't know whether that EPROM contains the "right" values for color indices 27 to 31.

Differences between CPC and KCc would be of great interest. The picture shows how it looks like on the CPC.

Strangely the OUTs to set colors work for other screens. Somewhere there is an interference... probably in the code before setting the colors... just don't have data about it. Therefore a KCc emulator would be great.

[GUNHED]

According to the wiki page, there are Java CPC desktop & Arnold.

Well, I need to check, but at least one of them seems to be a CPC in KCc mode anyway. But thanks for pointing me at them. 

[Prodatron]

The attached picture shall have black as border and background, but it doesn't work.

Maybe wrong Gate Array values, which lead to the same colours on an original CPC, but are different to the official ones?

Just have a look here ("Palette sorted by Firmware Colour Numbers"):
https://www.cpcwiki.eu/index.php/Gate_Array#Palette_sorted_by_Firmware_Colour_Numbers

All these not in brackets are the official ones. They should show exactly the same colour on the KC Compact. From my experience this works fine.
Can you check, if you use alternative values? Or maybe set bit5 (+32) by accident?

[arnoldemu]

I looked at FutureView I and II (correct ones to look at?) and I don't see anything with the code which would cause this problem.

What is the h/w configuration of the kc compact that shows this issue?

Also you say sometimes this happens on kc compact and sometimes not? Is there any way it shows more often?

[HAL6128]

Don't know if you are using Visual Studio Code for programming but there's a really cool plugin for installation available which not only let you program assembly but also go into debug and emulated mode for a CPC and KC compact.
Maybe it helps?

[Benedikt]

When I look at the KC compact's schematics, the only oddity I see in the palette circuitry is that the palette RAM is single-ported, which the system tries to mask by interrupting the clock signal to the RGB output latch whenever you write to the palette RAM.
I.e. you get repeated pixels on screen rather than much more annoying arbitrary snow artifacts.

The only two explanations I have for wrong colors are

• Wrong values in the color translation EPROM, e.g for undefined indices
• Flaky hardware

As far as emulators are concerned, I believe that Arnold might be quite accurate, because it has quite a few source files for KCc-specific hardware components.

[GUNHED]

Found a nice emulator here:

JKCEMU http://www.jens-mueller.org/jkcemu/

Will check if it is capable to reproduce the error with the simulated GA.