Section 4109 6:45p - 9:50p Fri Bus 263
will be used extensively to communicate with you.
Announcements, grade reports, and assignments will be posted here.
Please access the website from any SMC computer lab. Alternatively,
it can be viewed from an internet-connected browser anywhere. You
are responsible for awareness of the information posted here
Dropped from the class (this
Grades - refreshed today,
at the link entitled "Grade information" at left. (4/10)
Students to drop from the class
- these students appear to be inactive. I would like to drop them.
If you are one of these students, and want to stay in the class,
please tell me not to drop you and I won't.
Spring break - coming up.
There will be no class meeting April 17. (4/3)
Upcoming topic - will be processes
- after we do Chapter 2
read - textbook chapters we will cover on the topic of
processes. Those are chapters 3 and 9 (process scheduling).
anticipate - assgt 9, to be done later, after I have demonstrated how to do it in
Grades - refreshed today,
at the link entitled "Grade information" at left. All work
of which I am aware is included. Some of the recent assignments
turned in late received a grade penalty. (4/3)
sharing - a way to allow multiple interactive
processes to share a computer's CPU pioneered by Fernando
Corbato at MIT. (4/4)
this survey please - whose purpose is to improve the
computer science department. (4/2)
Grades - have been updated,
at the link entitled "Grade information" at left. (3/27)
do the reading in the Reading column of section 4 of the course outline.
do the assignments found in the "Homework" column of
sections 4 and 5.
Caching assignment due on
paper in class 3/27. did not have time to cover caching in
class on 3/20, plan to do it next class on 3/27, due in class 4/3
Some helpful explanation - here is how to correspond or reconcile
the vocabulary in the textbook problem, and that at the end of my
related writeup. There are 3 terms involved. What he calls Tm,
I call Tslow.
What he calls Tc,
I call Tfast.
What he calls "effective access time, I call Tave.
There is no difference between what he and I are talking about, it's
the same situation. The first term is talking about the native
access time of one type of manufactured physical memory, and the
second term about that of another. The second one is superior, does
its job (moving data in and out) faster, costs more no doubt.
Engineers buy that to make their caches. They buy the first, slower
kind to make their RAM memory modules (regular memory) that you
stick into the slots on your motherboard. The third term, on the
other hand, is a little different in that it isn't talking about the
native access time of anything. Rather, it's talking about the
access time that would be experienced in actually using the
computer. That doesn't match the native access time of either of the
2 memory types that the computer contains, since the computer uses a
blend of both so that the experienced access time will fall
somewhere in between their native times. Better than the slow one,
not as good as the fast one. But in doing the problem just recognize
= = Tslow
= = Tfast
effective access time = = Tave
sputnik down again,
Grades - have been published,
at the link entitled "Grade information" at left. (3/21)
Waste time in class - see
in-class exercise link, section 5 of course outline, entitled "waste time"
How interrupts save time - my
in-class example put some numbers on the textbook's figure 1.5, "Program Flow of Control
without and with Interrupts." I assigned time units to the
various portions of the program shown in the Figure, both the 5
numbered ones and the I/O Command. Then I calculated the elapsed
time from the start of the program till the time it finishes. I did
that twice, once where interrupts are not used (Figure's left panel
(a) ) and once where they are used (Figure's center panel (b) ). I
assigned/posited the following amounts of time:
1 - takes 6 units
2 - takes 20 units
3 - takes 18 units
4 - takes 4 units
5 - takes 4 units
I/O command - takes 8 units
If that were the case, I reached the conclusion that the program
as a whole would take 76 time units to complete if all phases ran
consecutively (i.e., without interrupts) in the order shown in the
Figure, versus only 60 time units if some phases ran concurrently
(i.e., with interrupts). A similar question appears on an upcoming test.
The question is to perform the
identical analysis/calculation, but with different input numbers
supplied. Be sure you can do this problem, and you'll be able to do
its companion problem on the test. (3/20)
of a stack - to keep track of where to return after a
function call. Shown in the gdb debugger (same one used
by ddd debugger you used). (3/20)
System calls - here's a cheat
sheet listing the approximately 200 system functions that user
programs can call, for various services. Here is some further
Grades - published, at the
link entitled "Grade information," at left. (3/20)
sputnik is back up - please
make sure you 1) are able and 2) know how to log into it (see 2/23
"Accounts created" posting, and the undated "A Remote Unix system account is available for your
use" and "Using ssh" postings below). Please upload
your binary math homework. (3/13)
do the reading in the Reading column of section 3 of the course outline.
do the assignment found in the "Homework" column of
Some helpful explanation about textbook's problem 1.1 at the end of
the chapter. It is very similar to the one in the book in Figure
1.4 (and the matching assembly language in-class exercise we did).
The difference is, he wants to get/put numbers from/to some
devices, instead of memory. So, he gives you 2 new instructions (to
go with the 3 you already know) in his hypothetical machine
language, for the purpose of shuttling data back and forth to
devices. The instructions require id's of some kind for
devices (just as memory locations require addresses, which serve as their
id's). The author doesn't provide id's for the devices, but you can
do so. You can make up your own id format and system. A good choice
for this academic exercise might be 3-digit numbers such as 001 for
device 1, 002 for device 2, and so on. Then, putting together the
drawing I ask for is a matter of showing the devices and their
contained values, and constructing a drawing pretty much the same as
the one in Figure 1.4.)
- there are 2 assignments in section 3 homework column.
Please perform the first, "some assembly language," on
sputnik by the end of the day Sunday 3/22. It leaves the result on
sputnik. Please do the second, "make a variation..." on
paper and submit it in class Friday 3/20. (3/19)
Web site change - I have
removed the "assignment" links in the right-hand column. They
were mostly duplicative of equivalent links in the course outline. Those that
were not, I migrated into the course outline or eliminated. So the course
outline is the centralized, official home of links to homework and other resources.
The current homework, about arithmetic in binary and hexadecimal number
systems, has a link in the homework column of the 2nd section of the
course outline. Please find it, and future homework links, there.
No class meeting tonight - with
apology for the late notice, our class will not be held tonight
March 6. The computer science department holds a "faculty flex
day" for which all the department's classes are canceled for
the day. If you are in contact with any classmates please tell them,
in case they may not check email or this web site. I'm sorry for any
inconvenience, ask you to have a good evening, and look forward to
seeing you next Friday March 13. (3/6)
Bootable flash drives for you
- containing a copy of linux similar to that on our classroom
laptops, is available for copying to your USB drive. Optionally, if
you are interested, bring an 8GB or bigger flash drive to class and
we can copy onto it an image of the USB drive I have prepared. It
seems to boot on several computers-- probably therefore yours. It's
persistent. It contains the utilities and configuration I think
useful for teaching. I have not road tested it on any scale but with
you as my guinea pigs, it's an offer. It is not required, and I
won't formally support things that may not work. No promises. But if
you are interested come to class with a flash drive and I think you
will leave with a linux environment in which to play. (2/27)
Due date for "Second homework"
below will depend on when we get sputnik remote server access
restored. I will keep you posted. Meantime go ahead and work out the
binary and hexadecimal problems in the assignment. (2/27)
Accounts created - per the
link below entitled "Remote Unix system account". Please
do the homwork item (under the link "First homework"
below) that asks you to perform an initial login. (2/23)
with approximate weekly topic coverage corresponded to related
readings, homework assignments, and in-class slides I will use.
Please follow this outline as we move through the topics, for assignments and reading
I want you to do (2/20)
The answer is ... (read the lights), what is the
question? Let's understand what these
pictures show. The device shows adding 6 and 5 to produce 11.
Here are "6
and 5". And here is "11".
Listen to this
video from the 7:30 timing mark to the end, describing addition
with switches to input addends, lights to output sums, and a 74xx
Texas Instruments chip to hold the "wiring" that does the
74xx chip in 1962? No such thing. My classmate then made a science
project that did the same thing as in the above video: switches to
input addends, lights to output sums. But how did he make the math
happen? He built the same functional circuitry as contained in 74xx
chips, from basic discrete circuit components ( resistors,
capacitors, inductors, diodes, transistors ). The
circuits he wired up are as shown here in the several kinds of
"logic gates" (scroll down to the circuit diagrams) and
further described here.
Here is another discrete
component enthsiast/purist's page. (2/20)
Second homework - please
do the assignment found in the "Homework" column of
section 2 of the course outline. anticipate
March 6 due date (2/20)
First homework - please
read chapter 1 of the textbook. Slowly. Twice.
read the 7 links about binary and other number systems,
below left, under the heading "Number bases" in the
"Foundation Concepts" section.
read - write-up at link entitled "Remote Unix
access with ssh" at left, and then:
log in - to your remote unix account. Please see section here
entitled "Remote Unix system account for you". I will see
your login history and record a minor grade credit for your having
logged in. Log in by this Friday 2/27. After
logging in, get out by running the "exit" command.
listen - to
about operating systems
(skip the part from the 6:00 minute mark to the 39:00 minute
mark). It spans a lot of topics that we'll encounter
in coming weeks, in a broad summary touching on all the items on the
OS's job description list (the ones in paragraph titiled
"Jobs" below). You
won't understand some of it, and I considered not asking you to
listen to it on the grounds that it bites off more than you can
chew. But that's what the coming weeks are for. Listen to it now.
Then, it would be interesting if you did so again after the course
to see if I taught you anything.
anticipate, from assignment 1.5, the book's problem 1.1 at
the end of Chapter 1, by reviewing the instruction execution example
in Figure 1-4 of the textbook and associated discussion. (2/20)
First personal computer - Altair
(click photo to enlarge, note
switches and lights on front panel)
PCBSD installation - time permitting I hope to demonstrate
the installation of an operating system on a laptop in class. I'll
use PCBSD. See this related
YouTube video and PCBSD's
Virtual machines - on class laptops (screenshot).
Jobs for which operating
systems have responsibility:
Slides we're viewing -
"Ch1 Computer Overview" - about interrupts, caching,
"OS Installation" - about partitions, MBR, boot
process, filesystems etc (2/20)
Listed homework assignments at right - will not
necessarily all be assigned.
So don't go off and try to do them all on that erroneous assumption.
They will be assigned selectively and explicitly. (2/20)
[those homework links at right have been removed (3/5) ]
Textbook - Operating Systems: Internals and Design Principles,
sixth edition, William Stallings, Pearson Prentice Hall. It
appears to be offered in an
online format. (2/20)
concepts you should be(come) familiar with as
background/prerequisite for this class:
Data structures (lists, stacks)
Binary and hexadecimal number representation
Compiling/linking/loading (symbols, address fixups)
Processor instruction sets
System architectures (bus, data lines, interrupt lines)
Use of ssh
Use of ftp/sftp
using class laptops
A Remote Unix system
available for your use.
Using ssh (secure shell). ssh is an important tool you will use
for interacting with remote computers. For that you will need an ssh
client. There are a number of ssh
Running linux at home.