Add license and readme (Thanks Dennis!)

LICENSE

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+This work is licensed under the Creative Commons Attribution-NonCommercial
+4.0 International License. To view a copy of this license, visit
+http://creativecommons.org/licenses/by-nc/4.0/ or send a letter to
+Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.

README.md

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+# Prime 50-Series Emulator
+
+## What Is This?
+
+This is a software emulator for a minicomputer architecture sold
+by Prime Computer from the early 70s through about 1993.  Prime's
+initial business plan was to make systems compatible with the
+Honeywell x16 family, which had then-recently been discontinued.
+Prime extended the architecture heavily.
+
+## Emulator History
+
+Beginning in 2005, Jim Wilcoxson developed an emulator for Prime
+Computer's 50-Series architecture.  The emulator originally ran on
+the PowerPC architecture.  In late 2011, Jim ported it so it would
+run on x86.  This entailed solving endianness issues (The 50-Series
+is big-endian), as well as re-optimizing the code for performanceu
+without the host processor having a large set of general-purpose
+registers.
+
+## Emulator Documentation
+
+Coming soon, we swear!
+
+## Public Systems
+
+There are a set of emulators available for public use.  These may
+be accessed via `telnet` to the appropriate port on `em.prirun.com`.
+
+| PRIMOS Revision | Port |
+|-----------------|------|
+| 18.3.1          | 8007 |
+| 19.2            | 8001 |
+| 20.2.8          | 8002 |
+| 21.0.6          | 8003 |
+| 22.1.4          | 8004 |
+| 23.4.Y2K.R1     | 8005 |
+| 24.0.0.r15      | 8006 |
+
+For example, `telnet em.prirun.com 8001`.
+
+## Prime History
+
+Some information about the Prime company is available in the FAQ
+which was assembled by denizens of the comp.sys.prime usenet group
+and Info-Prime mailing list around the time Prime's 50-Series
+business unit ceased to exist.  A reformatted copy is available
+[here](https://sysovl.info/reference_prime_faq.html).
+
+## Prime Documentation
+
+A growing collection of Prime and related documentation is available
+at [sysovl.info](https://sysovl.info/reference_prime.html).
+
+## Getting PRIMOS
+
+Two versions of PRIMOS are available from Bitsavers:
+
+* [Rev 22.1.4](http://bitsavers.org/bits/Prime/primos_22.1.4.zip)
+* [Rev 19.?](http://bitsavers.org/bits/Prime/pps/03_log.tape_I=boot_II=iptpal.tap.gz)
+
+The Rev. 19 tape is a save from an installed system.