| Popis: |
The environment provided by the multiprogrammed options of Operating System 360 is not the most suitable for debugging. It is primarily a batch system, with a programmer's card deck disappearing into the card reader and reappearing at some future time on a printer. What happens in between is often impossible to discern; any attempt to monitor a program's execution (e.g., the setting of an address stop) is so complicated that it is nearly impossible. In this environment, debugging is difficult---at the conclusion of a program, the programmer either has successful execution or some indication of program error. If he planned ahead (and was lucky), his output will include not only an indication of the actual error, if one occurred, but trace information (either through OS TESTRAN facilities or his own printouts) to help him determine the problem. However, he is usually presented with a dump, containing a numerical reference to the completion-codes manual. More importantly, the dump represents the state of the system when OS decided it could not continue the program's execution; the user must discover why it went wrong by educated guesses and by "playing computer" with his program. The difficulty and sheer wastefulness of this procedure is extremely evident. For this purpose, an on-line symbolic debugger can be invaluable. |
