Readme.Ultrix

This update now includes two multi-volume ULTRIX-11 RL02 images.
Also, I have updated the RT11 image which contains Multi-User Basic (MUBAS.SAV and MUBASX.SAV)
The RL01/02 code has been updated to allow for multi-volume images. The drive type is now
extracted from the image filename on the SDCard.
To create multi-volume images requires SIMH to build formatted RL01/02 images:
Create a working volume of your favourite OS in Simh eg Use RT11_V5_MUBasic.RL01 for a test.
Set the CPU to an 11/34  'set cpu 11/34'
Attach the working volume to rl0  'att rl0 RT11_V5_MUBasic.RL01' (Simh will set device to RL01)
Set the Simh volume type to RL01 'set rl1 rl01'
Create a new blank volume. 'att rl1 blank.dsk' (Overwrite last track ... Y) 
Boot the OS. 'boot rl0'
At the RT11 '.' prompt type 'init dl1:'
If you are a hardened RT11/Simh user, attach other volumes and copy stuff to DL1:
Exit from Simh '^e' and then 'bye'
Check the file size of blank.dsk. it should be 5243392 bytes.
Next I suggest you use HxD (https://mh-nexus.de/en/downloads.php?product=HxD20)
In the tool->file tools is a concatenate option. Add your working volume and then blank.dsk and create another disk image.
Make sure the final disk image has a .RL01 extension.
Copy this to the SDCard and power up the M5PDP11.
Telnet to the M5PDP11 console port. 'telnet m5pdp11 2000'
Tap select until you find the disk image you have just created and click Boot
You should now be able to use DL1: as well as DL0: with RT11.

Ultrix: All of the above applies to the Ultrix-V3.rl02 and Ultrix-V2-Full.rl02 images in that they contain 2 RL02 volumes.
These are concatenated RL02 volumes each of which is size:10486272.
The Ultrix-V2-Full.rl02 version is the last of the 18 bit compatible Unices and needs 2 RL02s! The important fact about this distro
is to type ^D (ctrl-d) at the first # prompt. This will start multi-user mode and you can connect
a second terminal via 'telnet m5pdp11' (port 23). Login as root ... no password required. In this version vi works. You can
login as user:niss1 pass:user01 to find a tiny c test programme and edit it with vi. Man xxx works as well, have coffee while
waiting for the listing. Even under SIMH this is slow!!!!
Ultrix-V3.rl02: I would say that this distro is more of interest than utility ... it is not quite BSD.
vi will not run as the app space is only 64K (no I/D split for the emulated PDP11). Nonetheless, it
clearly demonstrates that not much has changed at the Unix console since it arrived 40 years ago!
Finally, this closes the gap between the low end operating systems and the next step which is BSD 2.x and beyond.
If you wish to get BSD running on the ESP32 have a look at https://github.com/Spritetm/esppdp
or https://github.com/Isysxp/esppdp (for use with the latest ESP-IDF). This is a SIMH port to the ESP32.

Sept 2024

I have now updated the app to 22 bit addressing with a non split I/D space and a KT24 unibus map. This allows for sufficient memory
to run vi under Ultrix 3.1. An RL02 image can be found in the images directory (Ultrix_V3_UX24.rl02). As above, this is pretty close
to BSD 2.9. This is the last version of Ultrix that will run on a PDP11 (not sure if 3.2 ever existed). Versions above
this eg 4.x, need a VAX to run. The install tape can be found at: http://www.bitsavers.org/bits/DEC/pdp11/magtapes/ultrix-11/
It is also relevant to note that BSD 2.9 will now run on this app as it supports non-split I/D mapping. However, the available
tapes contain the entire source tree which is uploaded to the /usr mounted device. This requires at least 30-40 Mbyte
of disk space. Obviously it would be possible to extract some key directories onto a second RL02 and stay within the 10 Mbyte limit.
However running BSD 2.9 and above really requires a network interface. Jeroen Domburg (spritetm) has implemented this for the ESP32
wifi with an interface to a simh DEQNA device which is really cool. This works really well with the BSD 2.11 image he has built for
the esppdp app. So for anything beyond Ultrix 3.1, I would really recommmend a look at this app as it can run OSs other than
BSD 2.11 that may be built under simh. The next step would then be a VAX implementation for the ESP32!!!!!