Section 4104 6:30p - 9:35p Fri Bus 259
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.
No class meeting April 18.
Have a good spring break. See you April 25. (4/11)
Birth of the internet - at
UCLA's Boelter Hall room
3420. Here, of optional and casual interest (but hey! it's
interesting!) is a BBC
radio interview about it (first 9 minutes). (4/9)
survey - whose purpose is to help us improve the
computer science department.
The survey is available through Friday, April 11 at midnight. Please
take the survey if you care to. (4/5)
Spring break - coming up.
There will be no class meeting April 18. (4/4)
Upcoming topic - will be processes
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
sharing - a way to allow multiple interactive
processes to share a computer's CPU pioneered by Fernando
Corbato at MIT. (4/4)
Grades - updated, at the
link entitled "Grade information," at left, including the
"disassembly" and "figure 1.4, prob 1.1"
volunteers sought by L.A.
Hacks, for big confab at UCLA in 2 weeks. (4/2)
Waste time in class - see
in-class exercise link, lower right, 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. (3/28)
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). (3/28)
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
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 April 4.
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
Grades - published, at the
link entitled "Grade information," at left, including the in-class
3+2 exercise. (3/21)
Students dropped - Fotso,
Huang Jie, Joseph Lee, Mathes, Smith, Toll
This is reversible. If you remain in the class and wish to stay
enrolled please see me and I can give you a code to reinstate
Grades - published at link
entitled "Grade information" (3/14)
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.)
No class meeting this Friday 3/7
- see you next Friday 3/14. For your general information here's the
Homework - please
do the assignment found in the "Homework" column of
section 2 of the course outline. (2/28)
Textbook - I unexpectedly
received from the publisher a new (eighth) edition. It shows up on
the author's website (link at left for "7th edition" now
takes us to the 8th) but not yet on amazon apparently, so it
must be very new. We will stick officially with the 7th edition for
this class. (2/26)
(under active construction) -
with approximate weekly topic coverage corresponded to related
readings, homework assignments, and in-class slides I will use.
Please follow this outline week to week for assignments and reading
I want you to do (2/26)
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).
Homework - please
read chapter 1 of the textbook
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 next week. 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. (2/22)
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 (2/22)
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. (2/22)
Textbook - Operating Systems: Internals and Design Principles,
sixth edition, William Stallings, Pearson Prentice Hall. It
appears to be offered in an
online format. (2/22)
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 is
available for your use. (There are 2 students with the last name Lee. To
avoid duplication your account names are therefore leejacky and
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.