> My understanding is that the design motivation was to be able to > re-fetch a REFR load module in case of detected physical damage > to a page. Either lost in a redesign, or never fully implemented.
It goes back at least as far as later versions of the 360/65 machine check handler. I'm not sure it was ever implemented. IBM made lots of noises about how good /65 MCH was going to be, but they only delivered a reasonable version a few months before the /165s arrived. I remember when we moved from 360/50s to /65s, we had a short course from IBM on the differences that might affect our (intensivly Assembler F) code - this was one of them. It was a particular concern because we used an overlay structure in a DOS/360 programme we'd written for a 360/25. Under DOS, overlay segment swaps are under programme control and we used the segment reload function to reinitialiase variables - with only 16KB available for 250,000 instructions we couldn'd afford reinitialiastion code. It was written in an OS-compatible way - all OS-dependent stuff was in two-version modules. We spent quite some time checking out REFR before we decided it didn't affect us. Mutually exclusive with overlay anyway, as was just about every other LE attribute. It did worry us for a few weeks - we didn't know just how often a /65 might meet an error that would be recovered for a REFR programme but not for an overlay programme. When we dumped the /25 we had a BIG party and then spent a couple of weeks dumping the overlay structure. It made sense at the time, but not a few months later. -- Phil Payne http://www.isham-research.co.uk +44 7833 654 800 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
