Making an RT-11 TU58 Image

J Blaser oldcpu2 at
Fri Dec 5 15:12:37 CST 2008

On Thu, 04 Dec 2008 20:27:59 Tobias Russell said:

 > I've just managed to get a TU58 emulator compiled up
 > and running under Linux and confirmed its working by
 > booting Will Kranz's XXDP images
 > (

I use Will's emulator under MSDOS and works great for
me too!  With my first PDP-11, this was the only means
I had for backing up a handful of RL02 disk carts...

 > I'd now like to get an RT-11 TU58 image so I can run
 > a boot into a real operating system on my disk-less
 > -11s. Whats the best way to go about making a suitable
 > image?
 > I have a working RT11 v5 setup under SIMH. Is it
 > possible to make a suitable image via this? One
 > thought is to make a RX01 boot image and but with a
 > TU58 boot block and then use this on the emulator.

Yes, it's quite easy.  You can build an RX image, or
as hinted at above, you can create an entire RL02-sized
image and use it with the TU58 driver (DD).  It turns
out that RT11's DD driver only cares about size of the
media when it *writes*, but it can read any properly
initialized media of any size.

As you suggest, using SIMH, mount up a blank 'disk' of
whatever variety you want (RX01 would be fine, but a
little small for working with RT11 easily, I'd suggest
an RL01 or RL02), and initialize it, copy over the
files you want, and just as you say, do a COPY/BOOT
with the TU58 driver (DD), such as:


to put the TU58 driver in the boot block of a RL0x.

At this point you'll need to physically cable your
Linux box running the TU58 emulator and the PDP-11
with a simple null-modem cable.

When you fire up the PDP-11 hardware, you'll have to
enter the TU58 bootstrap (which Will gives in his
emulator documentation).  At that point you should be
home free.  It won't be fast, but it will certainly
function fine.

If you do create a non-TU58-sized virtual disk image,
you'll want to again refer to Will's docs where he
gives you a patch to the DD.SYS driver, setting the
number of blocks allowed.  This will allow you to read
and write to a larger (than standard TU58) disk image.

Good luck!

- Jared

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