As we discussed in the Interruptions section, Machine Checks are a kind of interrupt. In a sense, machine checks are generated by a failing hardware component in the hopes that enough of the hardware still functions well enough to process the interruption.

Since we will run MVS under the Hercules emulator, Hercules is what will provide the Operator Facilities. See the various HTML files distributed with Hercules itself, especially the Operating Procedure section of the hercinst.html page.

If you're using the Fish GUI on Windows, the Operator Facilities are available in a GUI rather than the normal linemode commands. I don't run the Fish GUI myself (since I run Hercules in Linux), so I can't really tell you where you need to look for the instructions; Fish maintains a webpage that probably has the answers, the URL should most likely be in the hercules-390 group's Links page on Yahoo!.

It's worthwhile to glance through this quite short chapter, just so you have an idea of what Hercules commands you might want to use to perform some of these operator facility operations.

The S/370 I/O model is somewhat different than most other hardware designs, and generally speaking offers high levels of performance on real hardware.

In terms of a S/370 hardware education, you can really say you "know" the S/370 until you've done I/O yourself. This tutorial will most likely not go that far.

We listed the Appendices when we introduced POPs. They contain some interesting things, including Appendix A which contains some instruction use examples. The POPs explanation of an individual instruction should always refer to an example when there is one. Furthermore, Appendix A contains a Number Representation section that beginning assembler programmers should carefully examine. Just about everything else in the Appendices are reference material.