include c:\cxpl\codes;               \intrinsic 'code' declarations
int N, I, T0, Time;
[for N:= 1, 3 do
    [T0:= GetTime;
    for I:= 1 to 100 do
        [while port($3DA) & $08 do [];  \wait for vertical retrace to go away
        repeat until port($3DA) & $08;  \wait for vertical retrace signal
        ];
    Time:= GetTime - T0;
    IntOut(0, Time);  Text(0, " microseconds for 100 samples = ");
    RlOut(0, 100.0e6/float(Time));  Text(0, "Hz");  CrLf(0);
    ];
]