I just observed that the BCC tool NeXTScreen may severely distort the run-time behavior:
program: PID motor regulation ver 0.89g ... 0.91g
PC: c2duo E6650 2*2.33 GHz 4GB RAM Win XP32 pro
same results at any (either) USB 2.0 port:
no polling, screen shot after program termination: approximates target quickly and smoothly
refresh rate 50ms: heavy perpetual jerking, no approximation at all
refresh rate 200ms: heavy initial jerking, approximation after a while
with another PC (Intel i7, 4*3.4 GHz, 4GB RAM Win XP32 home) everything is running fine at any polling speed.
is this normal?