One screen/three modes
1986 program by Petrel Informatique.
The two BASIC files are Listed in the video.
https://www.youtube.com/watch?v=Bfx_cCeZyfI (https://www.youtube.com/watch?v=Bfx_cCeZyfI)
Links:
https://www.cpc-power.com/index.php?page=detail&num=16687 (https://www.cpc-power.com/index.php?page=detail&num=16687)
https://cpcrulez.fr/info-petrel.htm (https://cpcrulez.fr/info-petrel.htm)
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.
*magic*!
Well, it'd have looked like it to my eyes back in '86...
Same here
Pretty clever !
I imagine the answer to how this was done is in the .BIN file but the way the effect is achieved is beyond me.
Can anyone explain?
It uses the fast interrupt of the CPC: when synchronized with the CRTC refresh rate @50Hz, it occurs 6 times per screen refresh (fast interrupt is performed every 1/300th second) so that you can define area and change mode very quickly at the line you want.
Quote from: Kris on 06:51, 11 June 21so that you can define area and change mode very quickly at the line you want.
The |3mode command is probably doing this. The (imho) clever part is the |Defmo command. I haven't checked the BIN but from the BASIC program, I would expects, that this command tells Basic which Mode is selected, then the program is drawing in an area which is set to this Mode. This makes sure that drawing graphics or text it doesn't create garbage on screen.