Here is a simple patch to make Tapper playable on machines faster than a 4.77 mhz XT.

With an HEX editor search for:
BA DA 03 EC A8 08 EC A8 08

and change to:
BA DA 03 EC A8 08 74 FB 90

Some animations and the bonus stage are not fixed, but the main stages run at the correct speed.

Interestingly the VSYNC routine was is the code, apparently in broke state:
mov dx,03DAh
in al,dx
test al,08h
in al,dx
test al,08h

that changes to:
mov dx,03DAh
novsync:
in al,dx
test al,08h
jnz novsync
nop