PDT$READW -- Read
Data from Pseudoterminal and Wait
Reads data from the pseudoterminal. The PTD$READW routine
completes synchronously; that is, it returns to the caller after
the data has been read.
For asynchronous completion, use the PTD$READ routine. The
PTD$READ routine is identical to the PTD$READW routine in every
way except that PTD$READ returns to the caller without waiting for
the data to be read.