8 Dec
2018
8 Dec
'18
1:24 p.m.
Are you using the same pack for the 8 and the 11
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:
it
around
on
(i.e.
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
mismatch
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 > 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 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 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 > 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 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