[comp.sys.3b1] XINU now available for 3B1

thad@btr.btr.com (06/13/91)

The following item just appeared in comp.archives.  Since I don't recall
having seen any prior mention of it here in comp.sys.3b1, I've reposted it.

Anyone know what this means?  Mt. Xinu sources for the 3B1???  (And, yes,
I know that ``Mt. Xinu'' is ``UNIX (tm)'' reversed end-for-end :-)

Thad Floryan [ thad@btr.com (OR) {decwrl, mips, fernwood}!btr!thad ]

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| From: eoneil@BBN.COM (Betty O'Neil)
| Newsgroups: comp.archives
| Subject: [comp.os.xinu] Xinu Vol. I for ATT7300 (3B1)
| Message-ID: <1991Jun12.213526.10816@ox.com>
| Date: 12 Jun 91 21:35:26 GMT
| Sender: emv@msen.com (Edward Vielmetti, MSEN)
| Reply-To: eoneil@BBN.COM (Betty O'Neil)
| Followup-To: comp.os.xinu
|
|
| A few weeks ago I wrote about about my port of Xinu Vol. I
| to ATT7300s, aka 3B1s or UNIX PCs.  Doug Comer answered the
| important question right away, saying it is fine to distribute
| it via anonymous ftp, so natually I had to then find time while
| giving finals, etc., to actually clean it up into presentable
| form.  I have now done that, and a README and a tar of the
| usual distribution tree is available in ~ftp/pub/xinu7300
| on host ftp.cs.umb.edu, currently at IP address 192.12.26.23.
| There is both the Xinu port and the software needed to run
| from the 7300's floppy disk to download and provide a debugging
| monitor for running/modifying Xinu.  The distributed Xinu sources
| themselves are as close to the original as possible.
| 
| These ATT7300 systems make great Xinu engines.  They come with
| at least 512K of memory, usually 1M, a MC68010, a simple paging
| system, and serial and parallel ports.  The hard disk burns
| out easily, but as long as the floppy still works to boot the
| standalone debugger/downloader you can run Xinu; the rest of
| the system seems quite sturdy.
| 
| --Betty O'Neil
| eoneil@cs.umb.edu, also eoneil@bbn.com
| 
| -- comp.archives file verification
| ftp.cs.umb.edu
| total 989
| -rw-r--r--  1 502          5050 Jun  4 20:56 README
| -rw-r--r--  1 502        993280 Jun  4 20:55 XINU.tar
| found xinu7300 ok
| ftp.cs.umb.edu:/pub/xinu7300/

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alex@umbc4.umbc.edu (Alex S. Crain) (06/13/91)

In article <3057@public.BTR.COM> thad@btr.btr.com writes:
>The following item just appeared in comp.archives.  Since I don't recall
>having seen any prior mention of it here in comp.sys.3b1, I've reposted it.
>
>Anyone know what this means?  Mt. Xinu sources for the 3B1???  (And, yes,
>I know that ``Mt. Xinu'' is ``UNIX (tm)'' reversed end-for-end :-)

	And to think that I seriously considered tossing my xinu books
recently, my my.

	The XINU referred too in the article is not Mt. XINU (commercial
MACH based BSD4.3 for assorted machines) but rather Douglas Comers XINU 
operating system. I haven't looked at XINU in some time, so this is all 
from memory.

	XINU is a multi tasking OS that was originally designed to be
downloaded onto a PDP-11 over a serial line. The idea is that you would
attach your PDP to a host, download XINU and a program image, type "go"
and watch it run. The image could then create more processes, talk to
a terminal, or whatever.

	XINU is multi tasking, but doesn't support virtual memory. Instead,
it works like mach threads, running different processes in the same address
space, allocating a piece of stack to each process. XINU handles the 
context switching and resource allocation (memory, semaphores, devices ...).

	This implementation is pretty minimal, sporting only a serial driver
and a line clock interface (to burp the context switch 60 times a second),
but the hooks are there for other drivers. XINU comes with a sample disk
driver, it shouldn't be too hard to swipe the disk driver code from the
diagnostics disk source.

	One of the most appealing things about XINU is the text written
by Dr. Comer for his OS class at Purdue, which describes, in detail, the
XINU design philosophy and details all the XINU procedures. Its well 
written and very complete.

	I may use XINU for a project that I've been working on, and I'd be
interested in hearing from anyone who does anything with the code. I 
recommend it strongly to anyone who wants to study operating systems, I'll
post an ISBN for the book when I dig up my copy.

	It would be a good thing if the code found a home in the archives.

-- 
#################################		           :alex.
#Disclaimer: Anyone who agrees  #                 Systems Programmer
#with me deserves what they get.#    University of Maryland Baltimore County
#################################	    alex@umbc3.umbc.edu