I assume as you are talking about PL/1 you have an IBM Mainframe application to be tested.
For Interactive Screen testing:
Tools that allow "green screen" testing through the use of an emulator will work these options include:
Mercury QTP and Winrunner (with the right add-ins)
Compuware QA Hiperstation
There will be other vendors that also provide these abilities.
I have not failed. I've just found 10,000 ways that won't work" --Thomas Edison