On Saturday, June 23, 2018 at 12:41 PM, Robert Armstrong wrote: > > Mark Pizzolato <m...@infocomm.com> wrote: > >Heisenberg effects mean that the problem is never seen > > Yep, the uncertainty principle applies to software as well... > > I'm just curious - do we (well, I don't, but somebody) have source listings > for > the KA655 EPROM? Supposedly one of the other hex numbers in the "?53 2 0A > FF 00 0000" message identifies the exact subtest that's failing. It might be > interesting to know that.
The listings we have are for a close, but not precise, version that the ROM is built from. Without regard to precise listings, the listings don't actually have a mapping of the test numbers (and sub test numbers) to specific tests. The assignment of tests is magically built by small macros that briefly define PSECTs that each tests contributes a little content towards. There must be some nice tool that can decode the resulting collection of test numbers and map them back to particular tests. Maybe a special interpretation of data in the link map might help get there, but how it is done isn't particularly obvious. ROM debugging is a very tedious process. You poke around in the ROM binary and disassemble a section. Then you locate particular instruction Sequences in the listing. Or you do the opposite (start from the listing and look for instruction patterns in the ROM). You then put simh breakpoints in some ROM locations that you want to stop at. The presence of breakpoints adds to Heisenberg variances since simh breakpoints are implemented by checking instruction fetch addresses rather than modifying the target code to insert actual breakpoint instructions (which are architecturally meaningful within the VAX simulation). For most things Heisenberg doesn't come into play, but timing calibration stuff is the exception. Anyway, this problem is benign enough, and the lack of solid debug data has it sitting there unsolved. - Mark _______________________________________________ Simh mailing list Simh@trailing-edge.com http://mailman.trailing-edge.com/mailman/listinfo/simh