On Sat, Dec 8, 2018 at 7:24 PM Paul Anderson via cctalk < cctalk@classiccmp.org> wrote:
> Are you using the same pack for the 8 and the 11 > I connected the drive I normally use with my 11/40 to the 8/e for testing to help narrow down where the fault was. I used a 16-sector pack in all cases. - Josh > > On Sat, Dec 8, 2018 at 8:54 AM Bill Degnan via cctalk < > cctalk@classiccmp.org> > wrote: > > > On Sat, Dec 8, 2018, 1:02 AM Josh Dersch via cctalk < > cctalk@classiccmp.org > > wrote: > > > > > On Fri, Dec 7, 2018 at 9:58 PM Josh Dersch <dersc...@gmail.com> wrote: > > > > > > > Hi all -- > > > > > > > > Finally got all the parts together (and my act together) to actually > > get > > > > an RK05 lashed up to my PDP-8/e -- only took a decade or so :). I > > fixed > > > a > > > > few problems with the RK05 and it appears to be behaving very nicely. > > > > > > > > The RK8E controller is mostly working properly but fails > interestingly > > > > when running the formatter, and during the exerciser -- on cylinder > 128 > > > and > > > > 192 and very infrequently on cylinder 64 it will get a cylinder > > mismatch > > > > when doing the seek. When running the formatter during the > > verification > > > > pass, on cyls 64 and 128 if I retry the read it'll continue without > > > issues, > > > > but it's never successful on a retry on cylinder 192. I tried > hooking > > it > > > > to the RK05 in my 11/40 and it exhibits the same behavior, so I'm > > > guessing > > > > the drive isn't at fault. And the error is consistent across packs > (of > > > > which I have only two). > > > > > > > > Apart from that fault the drive and controller seem to work fine -- I > > > > wrote out an OS/8 pack with Adventure on it (or at least the first > 191 > > > > cylinders of it) and it works without issue. > > > > > > > > Reading the RK8E service docs and schematics, the cylinder address > > > compare > > > > is done by reusing the CRC buffer, so I suspect the issue is in or > > around > > > > there -- the big problem is that debugging it is rather painful since > > > that > > > > logic is in the middle board of a three board set, with jumper blocks > > on > > > > top -- so bringing it out on an extender isn't an option. I'm > curious > > if > > > > anyone's seen this issue or is so very familiar with the logic that > the > > > > fault is obvious. > > > > > > > > I suspected the 7496 shift register at E14 which takes in the > cylinder > > > > address to be compared w/the header on disk, and I went ahead and > > > replaced > > > > it in the hopes that I'd get lucky, but no go. > > > > > > > > Anyone have any advice? > > > > > > > > Thanks, > > > > Josh > > > > > > > > > > > I'll add that during the format/verification the drive seeks properly > > (i.e. > > > it's not missing a step or overstepping), which I've confirmed by > > watching > > > the thing walk through the tracks with the cover off. > > > > > > - Josh > > > > > > > Partitions as rka0 / rka1? > > B > > > > > > > >
