While I fine-tuned (okay, corrected) yesterday's report about the current lifespan for MPE date intrinsics, my associate technical editor Vladimir Volokh suggested we include HP's documentation page for HPCALENDAR. That's the intrinsic HP wrote for the 6.0 and 7.x releases of the 3000's OS, a new tool to solve an old problem. Alas, HPCALENDAR is fresher, but it's only callable in the 3000's Native Mode.
But poking into the online resources for MPE Intrinsics, I stumbled on HP's re-shelving of its 3000 docs. No longer available at the easy-to-recall docs.hp.com, these manuals are at HP's Business Support Center. And just about nowhere else within a 10-minute search across Google's search engine. (Bing did no better.) So where are the guidelines to intrinsics for MPE/iX?
The Intrinsics Manual for MPE/iX 7.x is a PDF file at MMM Support. Independents like that support company help the community in using HP's resources for 3000s these days. It used to be much simpler. In the 1990s the Interex user group ran a collection of well-written white papers by George Stachnik. We're lucky enough to have them with us today, cut loose from ownership and firewalls. One is devoted to the system's intrinsics.
Stachnik explains why intrinsics tap the inherent advantage of using an HP 3000.
When an application program calls an MPE/iX intrinsic, the intrinsic places itself in MPE/iX's "privileged mode." The concept of privileged mode is one of the key reasons for the HP 3000's legendary reputation for reliability. Experienced IT managers have learned to be very wary of application programs that access system internal data structures directly. They demand that MPE/iX place restrictions on HP 3000 applications, to prevent them from doing anything that could foul up the system. This is what led to the development of the intrinsics. Application programs running in user mode can interact with the operating system only by invoking intrinsics.
Even if your company has a migration in mind, or doesn't have an unlimited lifespan for the 3000, knowing how intrinsics work is an intrinsic part of learning 3000 fine-tuning that might be inside classic applications. Tools can help to hunt down intrinsics, but it helps to know what they do and what they're called. You can fine-tune your 3000 knowledge using Stachnik's papers and HP's Intrinsic documentation.