You might think that the Tanenbaum book would be narrowly focused on
Minix. It isn't -- it covers operating system concepts in general.
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.
On 10/23/2016 12:23 PM, Dave Wade wrote:
Ray,
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.
Dave
*From:*Simh [mailto:simh-boun...@trailing-edge.com] *On Behalf Of *Ray
Jewhurst
*Sent:* 23 October 2016 03:20
*To:* Johnny Billquist <b...@softjar.se>
*Cc:* simh@trailing-edge.com
*Subject:* Re: [Simh] RT-11 source
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.
Thanks
Ray
On Oct 22, 2016 9:11 PM, "Johnny Billquist" <b...@softjar.se
<mailto:b...@softjar.se>> wrote:
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.
Both those points are missed with any Unix-like OS, even if the
intention is good.
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.
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.
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.
Johnny
On 2016-10-23 02:45, Nelson H. F. Beebe wrote:
Ray Jewhurst <raywjewhu...@gmail.com
<mailto:raywjewhu...@gmail.com>> asks today for documented
operating system source code for the PDP-11. Besides the
Lions' Unix
v6 code, there is also Doug Comer's Xinu project about which
he wrote
several books. Current versions are targeted at x86 and ARM CPUs,
http://www.xinu.cs.purdue.edu/
but he still provides code for older systems (PDP-11, SPARC, VAX):
ftp://ftp.cs.purdue.edu/pub/comer/
There is more about him here, including links to his books Web
site:
https://en.wikipedia.org/wiki/Douglas_Comer
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--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: b...@softjar.se <mailto:b...@softjar.se> ||
Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
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