PAL-SECAM CONVERSIONS
PAL
1. The number of scan lines, and therefore the frame time
increases from NTSC to PAL according to the following
table:
NTSC PAL
scan micro scan micro
lines seconds lines seconds
VBLANK 40 2548 48 3085
KERNAL 192 12228 228 14656
OVERSCAN 30 1910 36 2314
FRAME 262 16686 312 20055
2. Sounds will drop a little in pitch (frequency) because
of a slower crystal clock. Some sounds may need the
AUDF0/AUDF1 touched up.
3. PAL operates at 50 Hz compared to NTSC 60Hz, a 17%
reduction. If game play speed is based on frames per
second, it will slow down by 17%. This can be disastrous
for most skill/action carts. If the NTSC version is
designed with 2 byte fractional addition techniques (or
anything not based on frames per second) to move objects,
then PAL conversion can be as simple as changing the
fraction tables, avoiding major surgery on the program.