I'm going to show you the use of the
Michigan Terminal System, a large
computing system at the University of
Michigan Computing Center, using the IBM
model 36067. We will be using a standard
teletype, and we will be dialing in
through the ordinary University Centrex
Telephone System. This system can be used
by a telephone system anywhere in the
world, as long as we can dial directly
into the computer. These teletypes are not
wired in, but use the ordinary telephone
system. We start by pushing the originate
button, which turns on the teletype. Then
we will dial using the regular telephone
dial here. Now, there is a handset which
is available with every teletype system.
You can dial this number, if you like,
with the handset. Either one work, but as
soon as you are connected to the computer,
do not use the handset for any purpose at
all. Now, I'll push the originate button.
I can control the speaker volume with this
little knob, and so you can hear it. Now,
I will dial a number, 763-0300, or in a
Centrex system just 30300. And now, the
computer is coming in. And I will turn the
volume down. The response from the
computer is the identification of the
system. The who are you is the standard
teletype communication identification. And
the teletype itself answers with its own
built-in code number. In this case, the
teletype at the TV center. Now, I must,
sign on to the computer and identify
myself. The number sign at the beginning
of the line is the indication that the
Michigan Terminal System is waiting for me
to communicate something to it. The first
thing I must do is issue the sign on
command. All commands in the system starts
with a dollar sign. Now, the keyboard on
the teletype, is very much like the
keyboard of a typewriter, including a
shift key, for the characters on the top
of the key. We do not have upper and
lowercase letters, however. So, the shift
key is only used to get an additional set
of characters and in this case, the dollar
sign is the character above the number
four. Now, I will use the word Sign On,
which is the official command. Sign On.
There must be a space, at least one, after
every command. And now, I will give my own
personal computing center number, which
happens to be W010. Each user of this
system is issued a computing center
identification number, through his
instructor if he's a student, or through
the department for faculty. Now, this line
has been typed. It is being held by the
computer. But I can, if I see any errors
in it, do some editing and correcting. We
will see that later. I am satisfied with
this line and now I will give the end of
line character, which must be given after
every line and I will remind you each time
that I am doing it for a while. The
character for ending a line uses the
control key on the keyboard which is a
special key which indicates that I want to
use even additional characters besides
those that are added by the use of the
shift key. I hold the Control key down.
And while I hold it down, I can hit one of
a number of other keys. And in this case,
I will use the control with the letter Q.
It's possible to use the letter S also,
but that's right next to another key which
disconnects the teletype. So, I recommend
using Q. I will use control and Q to
terminate the line. And now, I'm asked to
give my private password. I'll give an
incorrect password, just some nonsense
characters and of course end of line
because I must indicate that I am
satisfied with that. I am prompted that I
better give another password and now since
I intend to give the correct password, I
will turn off the printing so that no one
can see what mine is. To turn off printing
we use this switch which is labeled HDX
and FDX, or Half Duplex and Full Duplex.
We normally operate this, the teletype in
Half Duplex mode. If I push it to Full
Duplex, printing is suppressed. And now I
will give my correct password, push the
Half Duplex again, and end of line
character control Q, and it is accepted by
the system. And I am now signed on. The
information that's coming out here is time
and date of the previous sign on and time
of date of this sign on. So, I can check
if anyone did use my number since I myself
did use it. Now, one of the first things I
will do is to change my password having
signed on correctly. I maybe concerned
that someone may have had acquired my
password and I will issue a command that
says $ set. Which is used for setting
various things in the system, but in this
case, I want to set my password to
something else. At least one blank after
each command. Pw is the name of my
password equals and no blank spaces in
here and now I will turn off printing
again, give my new password and terminate
the line. The number sign indicates that
I'm now ready to issue another command to
the system. Or now suppose we wish to
start using the computer and we wish to
enter some information into a file, I can
have a number of private files, each one
with a name that I invent, that's useful
to me. And I will attempt to create a new
file in this case by issuing a command,
Create. Dollar sign Create. And I think I
will illustrate here the fact that only
the first three letters of every command
are necessary. So, Create, space, let's
use the name EX. There is a check that I
don't already have one, and of course I
knew I had one of this name and we see now
that it was cut. To show what names I do
have, in case I've forgotten, let us run a
special program that is available from the
Computing Center Library, called Catalog.
So, I will say, run that program. The run
command is used to activate all sorts of
programs, my own private program as well
as the publicly available one, space, and
now the name of this program is Catalog
with an asterisk in front. I'll explain
the asterisk in a moment. End of line
character of course. Now, it is listing
out all the files that I have under my
private number. Now, the internal form of
a name like EX, is really W010EX. My own
identification is pre fix to it. And thus,
no one can reference my file unless he
signs in under W010. He can't do that
without knowing my password. Thus, I'm
protected as long as I protect my
password, which I do by changing it often.
Now, we see the names of the various files
that I had, including videotape which was
used to print out the title to this tape.
And, I did wanna create a file. I better
think of a name that isn't in there. So,
let's think of a name, like, 0X1. So, I'll
say create, X1. Now, space has to be found
on the, disk storage of the computer for
this. It has to be entered into the system
catalog of files. And now it's reported
back to me that this has been done. The
blank spaces after X1 remind me that I
could have up to twelve characters in a
name. I didn't choose to in this case. Now
I would like to enter some lines into this
file, and the lines will be numbered. I
can ask for automatic numbering of the
lines. So we'll give a command number. $
NUM and if I terminated the line at this
point, it would number them starting with
one in steps of one. Simple one, two,
three, four et cetera. But I will indicate
in this case starting with line one but
will use steps of three. All right. It's
now asking for line one. And I will simply
enter some information. This is the time,
and I misspelled the word. Let's look at
how we might make corrections here. One
way is to delete the whole line and start
over. To delete a line, I use control with
the letter N. This inserts a delete line
character into the line. If I like I can
continue with, with the new line that I
would like to have go in at that point,
and I'll do that in this case. And end of
line. Notice that since I asked for steps
of three, it is now asking for line four.
Let me, put some more information in here.
And I made another mistake. Well, again I
could use control N if I like, and this
time I'll terminate the line at that
point. And I get an indication that the
line was deleted. I didn't get the indic
ation in the previous case because I just
continued with the new form of the line.
Well, let me put the line in again. And I
made another mistake. Now, in this case I
really need to only backspace a character
and continue. Let me backspace two
characters to show how that could work.
The backspace is Control and the letter A.
If I get two of them, I have now back
space twice. And I can start the word come
again. Notice that the teletype does not
physically backspace as a typewriter does.
The backspace character is inserted in the
line, and when the line is processed by
the computer, it is interpreted to delete
the previous characters. We don't see that
on the teletype itself. So, I can add
another line here. All right, and now, let
me turn off the numbering, so that I can
begin to do some other things with it. I
can give dollar sign a number. End of line
character. That turns off the numbering
and it's waiting for me to do something.
Now, the file X1 is my active file in the
sense that whatever I do such as putting a
line in, goes into the currently active
file X1. To protect myself from doing
something inadvertently and damaging the
information in the file, I will release it
from being the active file by giving the
command Release. Now, for instance, if I
chose to put a line in like two I am
protected because I don't have any active
file. Now, since we did do a fair amount
of modification for the information in X1,
let us print out or list the information
in the file to see what actually got in.
Dollar sign, list. I can give the full
name if I like, X1. Looks very good. Now,
let me show how we can put a line in if we
want to make a modification. I can put a
line in with a number like two which will
go in the right place. I could even use
2.5. So, let us make X1 the active file
again and put a line 2.5 into that file.
X1 was active the first time because that
was created with the Create command. I
can't do that now. But I can make it the
active file by using a command Get. It's
acknowledged, and now X1 is probably the
active file. Let me try line 2.5. The
information in the line starts with the
character after the comma, the comma
indicating the end of the line number.
Now, let's verify that it actually got in
there. I don't want to list the whole file
X1, it could be a very long file. It isn't
in this case. So, what I'd like to do is
list a part of the file. Let's say, all
the lines. In the number range one through
five. There's a mistake, backspace, next
one, one two five. Notice that the line
2.5 was inserted in the proper place
according to its line number. And the end
of file comment here even though we didn't
get line seven has to do with the fact
that the name X1(1,5) named a new file
which was in fact made up of parts of an
old file. X1 lines one through five. Are
in fact a kind of a logical file. And when
it came to the end of that file, it
indicated end of file. There are other
ways to make new files out of old files.
We can use a process called Explicit
Concatenation. To do that, let me, for
example list a file made up of pieces of
old files. I will say, list. I have a long
file who's name is EX. So, I will take
lines 25 through 50. Oh, that's too long.
Let's back, cancel that out, 27. Now, with
the plus sign, I explicitly append to the
end of the, of those lines or concatenate
to them. Line some additional lines. Let's
say, lines 53 and 54. Notice that if it's
the same file again, I don't need the name
EX again. Now, I will concatonate some
lines directly from my terminal. So, I
need a name of my terminal as a file. We
use asterisk, source, asterisk. That is
the name of my terminal as an input file.
And then I will, maybe take some more
lines from file EX. If I just give one
number, it means all the lines from 100
on. And that's a long file, and so in
fact, we will see a fair amount of typing
at that point. In fact, that raises the
question, how do I interrupt somethi ng
which is going on that I would like to
stop? There is a special button on the
teletype called the Break Button. It is
located in various places on different
models of the teletype. In this case, it
is right here. Now, when I want to
interrupt, as we will see, whatever is
going on, I will push the break button. At
that point, because of the way the
teletype is built, the keyboard locks. And
I must, then, push a button which occurs
in another part of the teletype, called
the Brake Release Button. This button will
light, and when I push it, it will then
unlock the keyboard. Now, lets do it and
we'll see how the brake process works. I
will now give the end of line character.
So, that the line I just typed will in
fact go in. Line 25, 26, and 27. These are
lines from some computer program, 53,
there was no line 54. It is now waiting
for lines from the file called Source. And
so I must give a line. And since I'm
listing things on, on this terminal. When
I give a line as input, it'll come right
back out and be listed, as if it were in
that file. It's the first line in that
file. Well, now I have to have a way of
saying that's the end of this file that's
coming from my terminal, and so there's a
special character, Control C, for end of
file. Now, that's a character that went
into the line. I must now still terminate
the line. And then I will get an
acknowledgement that it's on in the file
and now it continues to line 100 of that
old file, EX. That's an interesting line
and I know that this file is quite a long
file with some programs in it and so now,
I will hit the break button and terminate
what's going on there. I get a response
from the computer that attention was
indicated. Now, I will hit the Brake
Release Button to pre-up the keyboard.
Which is lighted, when I push it, it goes
out, and now I can do something from the
keyboard again. The number sign indicates
that after an interruption by the break
button, the system is ready to have me
tell it what to do ag ain. Now, I'm going
to illustrate the use of one of our
language processors in the system. A
language called PIL, P-I-L, for Pittsburgh
Interpretive Language. And PIL is stored,
the processor for the language, is stored
in a file whose name is asterisks P-I-L. I
will run that program, that is the PIL
program itself by using the run command
and the name of the file in which the
program is found. I could indicate that
the source. Of input for PIL, is from some
other file. And have it read that file
directly. In this case, the sources of
input will be from my terminal. And so , I
will not say anything about it, and it
will as we say default to the terminal. We
will see the comment execution begins when
the loader finds that program and loads it
and begins it, and now PIL itself is
identifying itself as ready to go. I will
only introduce some of the features of the
language. A full description of the
language, as well as information about
using the teletype, is available at the
bookstores in a small booklet called
Introduction to PIL in MTS, Written by
Professor Larry Flanagan of the Computing
Center. Now, let me illustrate some of the
features of the PIL language, but only a
few of them. For one thing, I can ask for
Numeric expressions to be computed easily
three + four - two should come out five,
fine. I can say type the square root of
4.12345. I can ask for certain
trigonometric functions like the sign of
the square root of, notice I have a
different way of writing square root here.
It's not completely free English however.
And these are the only two ways. Now, I
can ask for, for instance, the value of x
+ one. And, of course, I get my wrist
slapped because I don't know what X is.
And so I can set, there's another PILl
language command, set X equal to three.
And now I can ask for a type X, x, X -
one, for example. Okay. Now it's possible
in PIL to build up a package of statements
into a program. And for that we give a
line number., which is consists of a
number in front of a decimal point. That's
called a Part Number, and then the Step
Number. I might say step 1.2 which I might
give as the man Y and Z. Now , that line
was not executed immediately, because we
have a line number, it indicates it to be
put away to become part of a package
program. Let's make line 1.3, 5Y + Z, as
well as Y and Z, and then line 1.4, is,
can we go to step 1.2. So now, we have a
program which will start off by demanding
two numbers from me, it will type out
their sum and each of them, and go back
and demand two numbers again. Now. In
order to actually carry out this
computation, I have to say do that set of
instructions. Since all these began with
one, this is called Part One. We could
have Part Two, etc. So I will say, Do.
Part one. It's asking for Y, as we
expected. I'll say Y is equal to five.
It's asking for Z. Z is equal to four. And
now the instruction to type the amount is
there, and now it's back to beginning,
asking for another Y. 79 and we see we can
do various things. Now, how do I stop
this, because it's always coming back to
ask for more? Well, in PIL, I could give a
break. I could hit the break button, but
in PIL, when it wants more information and
you have no more, you can use an asterisk,
which uses the shift key and way up here
the asterisk, and some character, any
character at all other than blank, I use X
usually. End of line, and that indicates
to PIL, that I interrupted the program at
step 1.2 where it was asking for input.
Incidentally, if I wanted to see what step
1.2 was out of some large program I could
say type Part One, and it'll tell me what
Part One was. Well, there are various
things we can do in this language. I will
illustrate one more. I can say four, and
without a line number, it'll be executed
immediately. 4I equal to one from one to
five by 2s, 5I + one. If it goes from one
to five by twos, it'll go in one, three,
and five. I + one should be two 46. So
let's see if it is. And now PIL is wai
ting for something else. Well, at this
point, I will stop illustrating PIL and go
back to the MTS system. Which should be
careful to distinguish that I have been
running a particular program in the
system. All of the file manipulation and
editing and correction were at the level
of the system itself. If I am talking now
to PIL, if I want to return to the system
to, for example, to sign off, I must go
back up to level of the system itself. I
do that by telling PIL the command system.
Execution terminates, and, we are now back
at the system. Let us review the commands
we have had so far. I have a file which
has the various commands in them. And if I
copy that file, we should see some that
we've seen, and there will be a couple
that we have not yet seen. Sign on. Create
to create a file. Get to make a file
active. Number to turn on the automatic
numbering, and a number to stop it.
Release to get rid of an active file. List
to find out what's in a file. We have seen
set and run. We have not yet used copy.
Although I used it to get this command
out, this list of commands. But the, the
main use of copy is to make a copy of one
file into another one. Perhaps, a
temporary file to be able to make changes
in it. So, for example, I will make a copy
of the file X1. I will copy it to a
temporary file, whose name will be minus,
something, minus J. Now, the minus sign
indicates that this file is to be created
just because I've mentioned this now. And
it will be destroyed when I sign off from
this terminal. Permanent files, whose
names don't begin with minus, such as X1,
are not destroyed. I could come back next
week and find X1 still intact. It takes a
little while to create a temporary file
because there is checking to make sure
that I don't have one already by that
name. It is not ready, and for example, I
will list just a line or two out of minus
J to convince us that X1 was copied into
it, let's list lines. Oh, just line one.
Fine. Now, minus J will be destroyed au
tomatically but well, before we get to
that, let's copy -J back into X1. In case
we want them to, after making some
changes, preserve it. Now, now if we
simply copy it back into X1, only the
lines that arrived from the other file
from -J will be replaced. Any old lines
will still be there. If I don't want to
have a mixture of old and new I will, do
well to empty out the contents of X1,
before I copy the new, new form of it back
in. And so, I will use a new command
called Empty X1. This doesn't destroy the
file. It only erases any contents that it
has. And now, this is a very important
point. We don't like to destroy
information unless we are sure that it is
the right information to be destroyed. I'm
being asked to confirm that it is X1 that
I want to, to empty, in this case. I give
okay, and that is a positive confirmation.
An exclamation mark would do, or O period,
K period will work. But anything else will
not. So now, X1 is in fact, emptied. It is
still there. If I wanted to completely get
rid of the file, I would say Destroy, as I
will after we Copy -J back into it. That
is done. And now I would have a new copy
if I had made modifications to -J. Now, I
will say Destroy X1, it asks for
confirmation. I will say, okay. And now,
for instance if I say Get X1, well it says
Ready, but as soon as I try to put
something into it like that, it will
report, there isn't any. As soon as it
comes back, I will Sign Off from the
computer. I, I will say Cancel in this
case. There isn't any others that I'd like
to do. All right. Now, I will sign off
from the computer by issuing the command
Sign Off. And now, I will get some
information summarizing the session that
I've just finished. The time of going off,
the elapse time. We have used thirteen
seconds in this case of computer time. And
then there's various other information.
The approximate cost of this particular
run was $3.20. This presentation has been
designed to make your work on the teletype
terminals e asier. For a review of this
material, you may wish to view this
material again, or to actually try it out
on the teletype, if you have a computing
center number. If you have any questions,
ask your instructor, or someone in the
counseling room at the computing center.
» Your attention please. Since this film
was produced, some changes have been made
in the MTS system. Three of which we now
call to your attention. First, to
backspace so as to delete a character.
Instead of Ctrl + A, use Ctrl + H. Instead
of Ctrl + A, use Ctrl + H. Second, while
Ctrl + Q may still be used to signal the
end of the input line, the Return key on
the right side of the keyboard may also be
used and it is usually more convenient.
Use the Return key to end the line. Third,
when dialing in, if nothing prints on the
teletype, within a few seconds after the
telephone connection has been made, type
the word Go. Go. Followed by the Return
key. The word go, and the return key.
Thank you.