On Sat, Dec 8, 2018 at 7:24 PM Paul Anderson via cctalk <
cctalk at classiccmp.org> wrote:
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 at classiccmp.org>
wrote:
On Sat, Dec 8, 2018, 1:02 AM Josh Dersch via
cctalk <
cctalk at
classiccmp.org
wrote:
On Fri, Dec 7, 2018 at 9:58 PM Josh Dersch
<derschjo at 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