Instead of this test:
cmp.b #50,VBlankFrequency(a6)
You could write a few lines of C:
#include <stdio.h>
#include <exec/execbase.h>
#include <proto/exec.h>
int main(int argn, char** argv)
{
printf("VBlankFrequency is %u Hz\n", (unsigned)SysBase->VBlankFrequency);
return 0;
}
This will just print out the frequency, it won't do anything else. You should probably do it via GfxBase if using 2.x or higher.
Pretty sure that can be trimmed down if you use dos.library print rather than C stdio.