Zap 't' Balls intro by Elmar Krieger

[ComSoft6128]

Intro to the Austrian Zap 't' Balls game which was released in 1993.

Unlike many demo text scrolls which consist of endless greetings to other coders this one has an interesting story to
tell - I would also suggest reading the informative interview at norecess.cpcscene.net below for more background.

Please note that when viewed on the 6128 the main scroll is quite
smooth but due to a hardware issue appears less so in this video.


https://www.youtube.com/watch?v=EwMLeoCdB_c

Interview with Elmar Krieger:

http://norecess.cpcscene.net/interview-elmsoft.html

Other Links:

https://www.cpc-power.com/index.php?page=detail&num=8455

https://www.cpc-power.com/index.php?page=detail&num=1322

https://www.cpc-power.com/index.php?page=staff&lenom=Elmar%20KRIEGER

https://cpcrulez.fr/info-static.htm

https://cpcrulez.fr/auteur-dr_felix.htm

https://cpcrulez.fr/auteur-elmsoft.htm

http://www.cpcwiki.eu/index.php/Zap't'Balls

http://www.cpcgamereviews.com/z/index.html

Not emulated - original hardware and software.

Please note that  the aspect ratio for this YouTube video is 16:9 but the CPC monitor
has an aspect ratio of 4:3 so you may wish to adjust your viewing device accordingly.

[vasilisk]

This is one of the few games that the colors in the intro are different, when you connect cpc to tv. In my sony trinitron the colors are like your video. In CTM644, the colors are the correct ones.

[ComSoft6128]

Yes @vasilisk there is definite colour shift with some demos when using the OSSC.
For 100% faithful reproduction it has to be the original monitor with the 6128 Plus/Scart combination coming second.
Most slideshows (but not all) are fine so I'm assuming that demos alter a setting or settings in the CRTC causing this
- maybe one of the hardware guys would like to comment?

[SyX]

Please note that when viewed on the 6128 the main scroll is quite
smooth but due to a hardware issue appears less so in this video.

Of course, you need a CRT display for being able to see the smooth scroll; but other funny thing is that you are capturing more screen space than a CRT can display, specially in the left and right borders (although up and down too); in those extra columns, you can see things that are not visible in a CRT display.

This is one of the few games that the colors in the intro are different, when you connect cpc to tv. In my sony trinitron the colors are like your video. In CTM644, the colors are the correct ones.

With respect to the different colours, this is a fun effect of those CRTs that are PAL and NTSC compatible, the PAL standard requires that during the back porch (the timing between the hblank finish and the start of the new scanline) the video signal is black (or blacker than black, but the CPC black is enough blackest).

In exclusive PAL tvs, the tv hardware generate that signal automatically, but in those multisystems tvs, that automatic black is not forced by the tv hardware. Then if you use the CRTC for making a shorter HBlank period and you set the border colour to a different one than black; the colour signal will get confused during the next scanline and you will get very different colours, some guys say that those new colours are random or not predictable... I will not say that because in the TV where my CPC was connected the colour pattern was very predictable.

I discovered this fx by accident during the last days of 2010, when I was trying to support rasters with pixel accuracy in CPC and CPC+ machines using the same code path. I had to read the boring PAL standard documentation for understand why this strange thing was happening. A few months later, I was speaking with some french guy, maybe Grimm, I don't remember now; the idea was showing this FX during the first Reset Party (there was another fun graphics FXs in that party, as the multiscreen picture from Sylvestre), but in the last moment it was impossible to go for me; but the guys there made a simply example in basic for showing those new colours in the CPC.

[vasilisk]

I dont know if this is a fun effect. But surely in the eye, it doesnt look nice. 

[SyX]

Hehehe, but everything is ugly until you make something fun with that fx.
This was the result of this fx during the Reset party:

[vasilisk]

ok. but why only in the intro? any special code there? Rest of the game, and main menu is ok.

[SyX]

ok. but why only in the intro? any special code there? Rest of the game, and main menu is ok.

Yes, I explained in my first post, using other words: during the intro, the screen is in overscan with columns outside of the cpc visible screen and the colours in the scanlines of those columns outside of the display are not black during the back porch time.

What happens in that moment is unspecified in the PAL standard specification; and by chance in TVs with support for NTSC/PAL destroys the colour generation, in the way that you will see new colours that doesn't exist in the cpc palette.
If I can and remember this night, I will upload other photos from my old examples where you see how the colours degrade in certain ways and in function of the colours used during the back porch time.

[Shining]

Something about Zap't'Balls I was always wondering about:


I bougth the Game very early, when it was released and cause I was a GT65 owner, my 6128 was nearly always connected to an old Colour-TV using scart. When I watched the intros "ZAP'T'BALLS - THE GAME MENUE" multiscroll, each of these scrollers showed a colour fading effect which I've never seen before and after that. As far as I know, such "effect" is not possible on classic cpc so I think, this had to do something with my TV back then. BUT I vaguely remeber, that I read an interview with Elmar back then, where he mentioned an effect in the intro which only works on real TV using scart and not on ctm644.


I still own a "modern" crtc tv and there the intro does not show this "effect".

[vasilisk]

Just for the record. What is the tv model?

[ComSoft6128]

https://www.lg.com/uk/monitors/lg-22MT49DF

[vasilisk]

https://www.lg.com/uk/monitors/lg-22MT49DF

Thanks. Although I was asking, @Shining  .
I forgot to mention him

[ComSoft6128]

Cool, but you made me remember something that I'll be posting in the hardware section in a moment