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<p>You might think that the Tanenbaum book would be narrowly focused
on Minix. It isn't -- it covers operating system concepts in
general.</p>
<p>I recommend the book more than the OS. Minix is written to be an
understandable classroom example. It does things that a serious OS
probably would optimize better. For example a generic hardware
interrupt handler adds a device specific interrupt handler to the
process queue that is scheduled as a high priority process by the
process scheduler. Unibus interrupts on a 780 weren't that bad.<br>
</p>
<br>
<div class="moz-cite-prefix">On 10/23/2016 12:23 PM, Dave Wade
wrote:<br>
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">Ray,<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">
I really suggest that you look at the Tanenbaum book. It
goes into each component of an operating system and explains
the structures that it uses and how the parts fit together.
Looking at the code often does not explain this. Even were
there are comments the usually don’t explain how things
mesh, which is all important.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">Dave<o:p></o:p></span></p>
<p class="MsoNormal"><a moz-do-not-send="true"
name="_MailEndCompose"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></a></p>
<span style="mso-bookmark:_MailEndCompose"></span>
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<p class="MsoNormal"><b><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif"
lang="EN-US">From:</span></b><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif"
lang="EN-US"> Simh
[<a class="moz-txt-link-freetext" href="mailto:simh-bounces@trailing-edge.com">mailto:simh-bounces@trailing-edge.com</a>] <b>On Behalf
Of </b>Ray Jewhurst<br>
<b>Sent:</b> 23 October 2016 03:20<br>
<b>To:</b> Johnny Billquist <a class="moz-txt-link-rfc2396E" href="mailto:bqt@softjar.se"><bqt@softjar.se></a><br>
<b>Cc:</b> <a class="moz-txt-link-abbreviated" href="mailto:simh@trailing-edge.com">simh@trailing-edge.com</a><br>
<b>Subject:</b> Re: [Simh] RT-11 source<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p>Thank you Johnny. I may ruffle some feathers, but I hate
C. I am mildly autistic and the way my mind works I
actually prefer assembly over high level languages. I would
really like a blueprint to see what I am doing. Is there
commented code for DOS/BATCH? Or even CAPS-11. I would like
love to see a fully commented kernel to see what I am up
against. <o:p></o:p></p>
<p>Thanks <br>
Ray <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Oct 22, 2016 9:11 PM, "Johnny
Billquist" <<a moz-do-not-send="true"
href="mailto:bqt@softjar.se">bqt@softjar.se</a>>
wrote:<o:p></o:p></p>
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<p class="MsoNormal">While we're at it then... Ray asked
for RT-11, since he felt that it was smaller and
simpler than most other operating systems available,
and also because he felt more comfortable with
assembler than some other language.<br>
<br>
Both those points are missed with any Unix-like OS,
even if the intention is good.<br>
<br>
I could just as well offer up RSX, since it actually
comes with source where the comments are still in
place, and it's actually written in assembler for the
most part as well. However, it is a much more complex
system than RT-11, and in some ways probably more
complex than Unix as well. So I don't think it might
be a good choice if you just want to understand how an
OS works.<br>
<br>
In fact, I would probably suggest Ray start with just
writing some code to do some simple things without
looking at existing code. The first thing needed would
be to just have something that can load programs from
a device, and run them. This will require some simple
device driver, some simple file system, and a simple
command line interpreter. Then you can go on an expand
from there. You'll soon realize things you want to
abstract away, and deal with in a somewhat coherent
way.<br>
I wouldn't bother with interrupt system, MMU, or any
more fancy stuff to start with. A plain 64K PDP-11,
with the program loader just located in one end, and
then go from there. Do system calls through TRAP, EMT
or some other instruction, and then have a vector
installed. If the user program overwrites that, tough
luck.<span style="color:#888888"><br>
<br>
Johnny</span><o:p></o:p></p>
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<br>
On 2016-10-23 02:45, Nelson H. F. Beebe wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Ray
Jewhurst <<a moz-do-not-send="true"
href="mailto:raywjewhurst@gmail.com"
target="_blank">raywjewhurst@gmail.com</a>>
asks today for documented<br>
operating system source code for the PDP-11.
Besides the Lions' Unix<br>
v6 code, there is also Doug Comer's Xinu project
about which he wrote<br>
several books. Current versions are targeted at
x86 and ARM CPUs,<br>
<br>
<a moz-do-not-send="true"
href="http://www.xinu.cs.purdue.edu/"
target="_blank">http://www.xinu.cs.purdue.edu/</a><br>
<br>
but he still provides code for older systems
(PDP-11, SPARC, VAX):<br>
<br>
<a moz-do-not-send="true"
href="ftp://ftp.cs.purdue.edu/pub/comer/"
target="_blank">ftp://ftp.cs.purdue.edu/pub/comer/</a><br>
<br>
There is more about him here, including links to
his books Web site:<br>
<br>
<a moz-do-not-send="true"
href="https://en.wikipedia.org/wiki/Douglas_Comer"
target="_blank">https://en.wikipedia.org/wiki/Douglas_Comer</a><br>
<br>
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-<br>
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<p class="MsoNormal"><o:p> </o:p></p>
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<div>
<p class="MsoNormal">-- <br>
Johnny Billquist || "I'm on a bus<br>
|| on a
psychedelic trip<br>
email: <a moz-do-not-send="true"
href="mailto:bqt@softjar.se" target="_blank">bqt@softjar.se</a>
|| Reading murder books<br>
pdp is alive! || tryin' to stay
hip" - B. Idol<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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