Skeezics Boondoggle<p>Time to cast a wider net, but I'm not a fan of the "throw 58 hashtags at it to see what sticks" shotgun approach, so I'll just ask the handful of <a href="https://oldbytes.space/tags/PERQ" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>PERQ</span></a> nuts still around to look to their left, look to their right, and point out the person who might have the PNX sources or documentation I seek. (If it's neither of them, maybe it's YOU! Go get that dusty old box of 8" floppies from the back of that shelf and bust out the Catweasel.)</p><p>Because surely someone, somewhere, remembers SERC, the 1980s, Chilton, RAL, ICL Dalkieth, PNX, etc. -- and squirreled away some docs, or diskettes, or even a whole PERQ with *some* information about the "C-Codes" instruction set and virtual C machine architecture of PNX. NMOC? Bletchley Park? Beuller? Anyone? There can't possibly still be concerns about throwing a copy of the sources over the transom 40 years on for research and preservation.</p><p>In the meantime, reverse engineering the kernel's microcode debugger is arduous and painstaking. Here's where we're at after a floppy or hard disk boot: both halt in a similar manner, somewhere at or before attempting to tekload the updated Z80 firmware. I'll get there, eventually, through sheer doggedness. But PNX kernel hackers of yore, lurking in <a href="https://oldbytes.space/tags/vintagecomputing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>vintagecomputing</span></a>, long free of ICL's closed-source bloody-mindedness, chime in anytime. :-)</p>