17 Oct
2013
17 Oct
'13
6:17 a.m.
On Oct 17, 2013, at 12:43 AM, Ethan Dicks <ethan.dicks at gmail.com> wrote:
I seem to recall that the CQD-220 will operate in an 18-bit
backplane. I could be misremembering. I can't think of why
it wouldn't, as long as the driver doesn't try to give it
any addresses over 56KB.
The CQD-220 (and most other QBUS SCSI cards) should work fine
with the CPU, but bear in mind that an MSCP bootstrap isn't
as easy to find (it's on late revisions of the KDF11-Bx ROM,
possibly elsewhere) and it's NOT the sort of thing you want to
toggle in yourself because MSCP is pretty complex (for a boot
protocol, anyway). Fortunately, I know at least the CQD-220
has a bootstrap built in which you can make available at 173000
(the standard boot vector) and one alternate location (memory
says 171000, but that could be misremembered as well). You can
also boot from the utility menu, but that requires manual
intervention at boot time, so I assume you'd rather avoid that.
A Zip drive makes a great drive for RSX-11M. 100 MB is actually
pretty big for that. I don't know if I'd do a Jaz drive for it,
but part of that is that I've had TERRIBLE luck with Jaz media
(from the '90s on) while Zip disks have been rock solid for me.
Stick with Zip 100 drives and media, and you should be good; the
later 250/750 drives and media suffered from poor quality
control and don't seem to last nearly as long.
The manual (http://www.vt100.net/docs/vt520-rm/ek-vt520-rm.pdf)
doesn't say much about that. There's a "graphics mode", which
looks like it's just VT100-style line characters, but it does
specifically mention that it doesn't do Tex 40xx graphics, and
I don't see the ReGIS escape codes anywhere in the manual.
- Dave
Perhaps someone here who has done it could comment,
but I'd
want to check the current draw against what the VT103 PSU
can provide. You might be able to get away with a KDJ-11 board
of some kind. With more memory, those other operating
systems become viable. 2BSD wants at least 1MB, ISTR,
but 4MB would be grand (if the PSU could handle it). TSX-11
probably runs in 256MB or less, but it's been years and I"m
not sure what the requrements are. Older versions of RSX-11
run in 256KB. A hard disk of some kind becomes
your next sticking point. You'll have to power the disk
externally, but even an RLV12 and a an RL02 or two
is a huge step up from dual RX02 (I made my living for
a year in the late 1980s with an 11/23 and a single RL01
running RT-11 v5.x, so you don't need 400MB to do
interesting things - even 10MB or 30MB is a lot).
I've definitely run 2.9BSD in less than 1MB, but as you said
elsewhere, 2.11 needs a lot more and requires split I/D.
Older RSX-11M will run in at least as little as 56KB (not
sure if 4.6 will or not, but it definitely runs fine on 256KB).
RSX-11M+ requires at least 512KB.
What would be
the suggested hard drive options ? Will CQD-22 SCSI work on
the existing CPU ? Will it work with a larger CPU with an upgraded bus
within the VT103 ?
I think both of those are true. I haven't tried running a Q22 disk
interface in a Q18 backplane, so I I'd
like to consider some sort of SCSI->ATA->flash
solution for low power and put it inside the VT103 for a self contained
approach. The mounts are not standard, otherwise ZIP drives or JAZ drives
in place of the DECtape IIs would offer immense storage and easy switchover
to other 11 OSes.
A SCSI interface and a ZIP or JAZ drive should be fine, for as
long as your media lasts. One thing to watch for is your operating system of
choice must
support MSCP disk to use a SCSI controller. This means RT-11 v5
not v4, AFAIK, but others on this list probably know detailed
specifics off the top of their head. 2.9BSD does not support
MSCP (but can be patched) and 2.11BSD does not support
processors that don't have split I&D (like your CPU or the KDF-11
in an 11/23 - you have to move up to a KDJ-11 to run 2.11BSD
on a Qbus box)
The CQD-220 manual actually has a table of supported operating
systems in the front or back, which gives a pretty decent idea
of which ones should work. I run mine with RSX-11M 4.6 just
fine.
Unrelated,
anyone know if the VT525 does Regis graphics ?
Unknown (I don't have anything that new), but I thought it did.