17 Sep
2021
17 Sep
'21
9:32 p.m.
FYI: The KS11 MMU for the 11/20 was built by CSS and was not on the
product list as it were. To my knowledge, no hardware or prints of it
survive. I've been told it was much more similar to the MMU in the KA10
than the scheme eventually done for the 11/45/55/70 and the 11/40 class
systems - but I think Noel has done more investigation than I have. So if
others have more info, please chime in.
As Warner points out the oldest code base we have is Fifth Edition. I'm
not sure if the KS11 code is still there. I did not think so. I thought
it ran on 11/40 and 11/45.
The V1 work was for a PDP-7 and is before the first 11/20 was secured. The
point is that I think there is a hole in the the SW we have.
As for RK03 vs. RK05 -- *I think I can help a little*. RK02/RK03 used an
RK-11C. I'm fairly sure that the RK05, used the RK11-D controller. The
'72 peripherals' handbook describes the former and the '76 the later. But
if you believe the handbook, both supported 203 cylinders and 2.45M
bytes/disk with 512 byte sectors. The difference seems to have been in
drive performance.
On Fri, Sep 17, 2021 at 10:34 AM Warner Losh <imp(a)bsdimp.com> wrote:
On Fri, Sep 17, 2021 at 8:10 AM Roland via TUHS <tuhs(a)minnie.tuhs.org>
wrote:
Hello Unix fanatics,
I have a PDP11/20 and I would love to run an early Unix version on it.
I've been working on the hardware for a while and I'm getting more and more
of the pieces back online again. The configuration will be two RK05 hard
disks, TU56H tape, PC11 paper tape reader/puncher and a RX01 floppy drive.
Unfortunately I don't have a MMU or paging option. But it seems that the
earliest versions of Unix do not need the extra memory.
Does anyone have RK05 disk images for these early Unix versions? That
would be a great help. Otherwise it would be great to have some input about
how to create a bootable Unix pack for this machine.
V5 is the earliest Unix we have contemporary images from. We have
fragments from everything else earlier, including files scavenged/recovered
from early DECtapes and some code recovered from kernel listings from a
Unix course that was put together by Bell Labs...
The Unix 1972 project that some TUHS members did. I think it's in the TUHS
distribution archive, but also on github. I think Warren Toomey's repo is
the canonical one https://github.com/DoctorWkt/unix-jun72 but
https://github.com/c3x04/Unix-1st-Edition-jun72 has a couple of newer
fixes for a docker file to contain the simh simulator. I'm unsure what
hardware that's supported, though. The machine file suggests:
rk03/rk11 177400 disk RK
dc11 174000 tty? (not supp?)
tc11/tu56 177340 dec tape DTn (not showing up in simh?)
rf11/rs11 177460 fixed head disk RF
kw11-l 177546 clock CLK
pc11 177550 paper tape PTR/PTP
asr-33 177560 tty? TTI, TTO
which has an RK03, not sure how close that is to an RK05, so some tweaks
may be needed.
Warner
A bit about the hardware restoring is on the
vcfed forum:
https://www.vcfed.org/forum/forum/genres/dec/78961-rk05-disk-drive-versions
https://www.vcfed.org/forum/forum/genres/dec/80723-pdp11-20-restoring
Booting RT11 from RK05
https://youtu.be/k0tiUcRBPQA
TU56H tape drive back online
https://youtu.be/_ZJK3QP9gRA
Thanks in advance!
Roland Huisman