Expanding Port Bits of the Parallel Port

Expanding Port Bits of the Parallel Port For many complex applications, the 17 I/O bits that the parallel adapter offers may be insufficient. There are many ways to expand the I/O ports — the choice of a solution may depend on whether you’re using the parallel adapter in the standard form or the enhanced form. Although the amount of extra hardware required to add I/O ports to the parallel adapter remains more or less the same for the standard adapter and the enhanced adapter, the software overheads are slightly larger for the standard adapter expansion.