If you can find a copy of "8088 Assembler Language Programming: The IBM PC"
by Willen and Krantz, 2nd ed. pub. by Sams, there is a discussion of the
game control adapter, monostable multivibrators, and conversion to other
uses, as well as an assembler program. If you need greater accuracy, there
is no reason you couldn't modify the approach to suit your needs.