For a dozen years now, I've either been a systems programmer, or managed other systems programmers. And I am ashamed, yes, ashamed to admit that I never bothered to learn EXCP. I always regarded EXCP as being in the class of solutions for which there is no known problem; the access methods take care of I/O for all IBM devices, so who cares about EXCP?

It turns out that EXCP is useful if you want to learn about HDA errors on your 3350-3370-3380 drives. EXCP is essential if you have non-IBM supported devices in the machine room (CDR and the Heath clock come to mind, if you aren't using BTAM to get to them).

These two sessions reviewed at a high-level those macros necessary to get EXCP rolling, and the formats and vagaries of the IBM channel command language.