What is PAL and NTSC?
In different countries there are different kinds of TV-sets and monitors.
Some have a broader picture and some have a more quadratic format.
These formats are called Videonorms, of which PAL and NTSC are the
most important ones.
PAL is used almost all over Europe, and also Australia. France uses
SECAM, but SECAM is very similar to PAL.
NTSC is used in the USA, Canada and Asia.
Why is that important for my C64 programs?
C64 programs accesses the monitor directly. When displaying any
grafical output, the C64 has to provide all the data to monitor
before the monitor displays it. That means that the c64-program has
to adopt to the speed of the monitor.
One frame of a NTSC-monitor is build up quicker than a PAL-frame,
which means that the c64 has basically less time on NTSC. To make up
for this, Commodore has made the NTSC-C64 a bit faster than the
PAL one, but besides this calling for other problems, the NTSC-c64
still has to struggle harder than the PAL one.
This is why many PAL-programs can hardly or not at all be adopted
to NTSC, they require more time to operate.
NTSC-programs mostly run on PAL-
mashines - many do flicker, though.