NTSC2PAL

Discussion about ZX80 / ZX81 Software
Post Reply
User avatar
GCHarder
Posts: 266
Joined: Sat Dec 14, 2013 7:46 pm

NTSC2PAL

Post by GCHarder »

This little routine will run a NTSC system at PAL speed. It does this by
bypassing the ROM's Display-3 routine, which then allows us to change the
margin value from 31 to 55.

See enclosed text for more info.

Demo video...

https://youtu.be/ZsgqFKky3a0

Regards;

Greg
Attachments
Hardware sreen shots
Hardware sreen shots
NTSC2PAL.zip
Program and support files
(28.04 KiB) Downloaded 32 times
bola_dor
Posts: 187
Joined: Wed Oct 02, 2019 5:32 am

Re: NTSC2PAL

Post by bola_dor »

Impressive!!!
ZX80, CZ1000, CZ1500, CZ2000, CZ1000Plus, CZ Spectrum, Sinclair QL.
bola_dor
Posts: 187
Joined: Wed Oct 02, 2019 5:32 am

Re: NTSC2PAL

Post by bola_dor »

I know very little about MC but I guess you are enlarging the amount of the lines in the margin letting more time for the CPU per cycle but not diminishing the active lines in the screen correspondingly in order to keep the Vertical Sync timing. I don't know if that's would be an easy task but it would provide a fantastic way to control speed vs screen in practically any aplication..
Better than a turbo switch.. and keeping compatibility with display systems..
Do you think it is possible?
ZX80, CZ1000, CZ1500, CZ2000, CZ1000Plus, CZ Spectrum, Sinclair QL.
Post Reply