RT-11 installation

From: Jerome H. Fine <jhfinexgs2_at_compsys.to>
Date: Thu Dec 2 09:49:49 2004

>David Betz wrote:

> Oops. I made a mistake in my original post. The command I typed to
> copy the distribution disk was:
> That's what the installation instructions say to do anyway.
> I've actually gotten a boot disk created now. It seems that the V4
> version of RT-11 I was originally using didn't really do the COPY/BOOT
> command correctly. I found another V4 boot disk and was able to use it
> to create a bootable V5 disk. I now have RT-11 V5 and the DECUS C
> compiler and linker all on one disk. This is something I could never
> do with my old PDT-11/150. It only had RX01 floppies and all that
> won't fit on a single density floppy. It's nice to have a bit more
> space with RX02 drives!

Jerome Fine replies:

Even though the CSR/VECTOR addresses of RX01 and RX02
drives are the same, they are VERY different programs
with regard to the device drivers, DX.SYS and DY.SYS,
respectively. Thus, an RX01 bootable floppy can't
boot in an RX02 drive and visa versa.

HOWEVER, although it is NOT possible to read an RX02
floppy (with double density data or 988 blocks on the
floppy) on an RX01 drive, it is possible and NORMAL
to read an RX01 floppy (with single density data or
494 blocks on the floppy) on an RX02 drive.

You probably understand this now, but other RT-11 users
may not.

In addition, the device driver for the PDT is again
different (as far as I understand) from the RX01 device
driver even though the media is the same (again as far as
I understand). NOTE that I have never used a PDT system.

As for more recent distributions of RT-11 up to V05.03
of RT-11, they are available at:

If you can manage to have a hard disk drive with
the PDP-11/23, that makes like even better. While
a SCSI host adapter is still expensive, SCSI drives
are not. An RQDXn controller is low in cost, but
decent compatible hard drives are hard to find.
Don't try to use an RD53 since they are no longer
reliable. RD52 drives are still OK, as are RD51
drives which are just 10 MByte Seagate ST-412 drives.

How you transfer them to your PDP-11/23 is a problem
I can't help you with. For myself, I use the MSCP
device driver, DU.SYS, which I have on both a PC
(under E11 with a Sony SMO S-501 and an Adaptec
AHA-2904AU) and the real DEC hardware (with a the
CQD-220/TM host adapter and the same SMO S-501).

In addition, DSD produced an RX03 compatible
floppy media which is able to use RX02 media
PLUS double sided RX02 compatible media. While
DEC never did correct the code in DY.MAC to allow
for double sided drives (it was present in V04.00
of RT-11), a DYX.SYS device driver is available
which handles RX03 media on the DSD which also
allows the use of memory beyond the 256 KByte
boundary via a bounce buffer. It is also possible
to re-wire a DSD drive so that single-sided media
are used rather than punching the extra holes in
the floppies when the user wants to use both sides
of the floppy. A DPDT switch allows the user to
select how the floppy is used.

If you have any RT-11 questions, please ask!

Sincerely yours,

Jerome Fine
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Received on Thu Dec 02 2004 - 09:49:49 GMT

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