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I'm going to show you the use of the
Michigan Terminal System, a large

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computing system at the University of
Michigan Computing Center, using the IBM

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model 36067. We will be using a standard
teletype, and we will be dialing in

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through the ordinary University Centrex
Telephone System. This system can be used

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by a telephone system anywhere in the
world, as long as we can dial directly

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into the computer. These teletypes are not
wired in, but use the ordinary telephone

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system. We start by pushing the originate
button, which turns on the teletype. Then

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we will dial using the regular telephone
dial here. Now, there is a handset which

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is available with every teletype system.
You can dial this number, if you like,

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with the handset. Either one work, but as
soon as you are connected to the computer,

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do not use the handset for any purpose at
all. Now, I'll push the originate button.

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I can control the speaker volume with this
little knob, and so you can hear it. Now,

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I will dial a number, 763-0300, or in a
Centrex system just 30300. And now, the

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computer is coming in. And I will turn the
volume down. The response from the

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computer is the identification of the
system. The who are you is the standard

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teletype communication identification. And
the teletype itself answers with its own

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built-in code number. In this case, the
teletype at the TV center. Now, I must,

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sign on to the computer and identify
myself. The number sign at the beginning

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of the line is the indication that the
Michigan Terminal System is waiting for me

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to communicate something to it. The first
thing I must do is issue the sign on

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command. All commands in the system starts
with a dollar sign. Now, the keyboard on

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the teletype, is very much like the
keyboard of a typewriter, including a

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shift key, for the characters on the top
of the key. We do not have upper and

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lowercase letters, however. So, the shift
key is only used to get an additional set

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of characters and in this case, the dollar
sign is the character above the number

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four. Now, I will use the word Sign On,
which is the official command. Sign On.

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There must be a space, at least one, after
every command. And now, I will give my own

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personal computing center number, which
happens to be W010. Each user of this

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system is issued a computing center
identification number, through his

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instructor if he's a student, or through
the department for faculty. Now, this line

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has been typed. It is being held by the
computer. But I can, if I see any errors

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in it, do some editing and correcting. We
will see that later. I am satisfied with

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this line and now I will give the end of
line character, which must be given after

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every line and I will remind you each time
that I am doing it for a while. The

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character for ending a line uses the
control key on the keyboard which is a

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special key which indicates that I want to
use even additional characters besides

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those that are added by the use of the
shift key. I hold the Control key down.

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And while I hold it down, I can hit one of
a number of other keys. And in this case,

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I will use the control with the letter Q.
It's possible to use the letter S also,

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but that's right next to another key which
disconnects the teletype. So, I recommend

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using Q. I will use control and Q to
terminate the line. And now, I'm asked to

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give my private password. I'll give an
incorrect password, just some nonsense

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characters and of course end of line
because I must indicate that I am

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satisfied with that. I am prompted that I
better give another password and now since

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I intend to give the correct password, I
will turn off the printing so that no one

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can see what mine is. To turn off printing
we use this switch which is labeled HDX

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and FDX, or Half Duplex and Full Duplex.
We normally operate this, the teletype in

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Half Duplex mode. If I push it to Full
Duplex, printing is suppressed. And now I

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will give my correct password, push the
Half Duplex again, and end of line

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character control Q, and it is accepted by
the system. And I am now signed on. The

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information that's coming out here is time
and date of the previous sign on and time

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of date of this sign on. So, I can check
if anyone did use my number since I myself

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did use it. Now, one of the first things I
will do is to change my password having

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signed on correctly. I maybe concerned
that someone may have had acquired my

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password and I will issue a command that
says $ set. Which is used for setting

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various things in the system, but in this
case, I want to set my password to

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something else. At least one blank after
each command. Pw is the name of my

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password equals and no blank spaces in
here and now I will turn off printing

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again, give my new password and terminate
the line. The number sign indicates that

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I'm now ready to issue another command to
the system. Or now suppose we wish to

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start using the computer and we wish to
enter some information into a file, I can

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have a number of private files, each one
with a name that I invent, that's useful

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to me. And I will attempt to create a new
file in this case by issuing a command,

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Create. Dollar sign Create. And I think I
will illustrate here the fact that only

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the first three letters of every command
are necessary. So, Create, space, let's

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use the name EX. There is a check that I
don't already have one, and of course I

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knew I had one of this name and we see now
that it was cut. To show what names I do

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have, in case I've forgotten, let us run a
special program that is available from the

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Computing Center Library, called Catalog.
So, I will say, run that program. The run

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command is used to activate all sorts of
programs, my own private program as well

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as the publicly available one, space, and
now the name of this program is Catalog

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with an asterisk in front. I'll explain
the asterisk in a moment. End of line

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character of course. Now, it is listing
out all the files that I have under my

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private number. Now, the internal form of
a name like EX, is really W010EX. My own

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identification is pre fix to it. And thus,
no one can reference my file unless he

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signs in under W010. He can't do that
without knowing my password. Thus, I'm

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protected as long as I protect my
password, which I do by changing it often.

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Now, we see the names of the various files
that I had, including videotape which was

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used to print out the title to this tape.
And, I did wanna create a file. I better

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think of a name that isn't in there. So,
let's think of a name, like, 0X1. So, I'll

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say create, X1. Now, space has to be found
on the, disk storage of the computer for

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this. It has to be entered into the system
catalog of files. And now it's reported

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back to me that this has been done. The
blank spaces after X1 remind me that I

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could have up to twelve characters in a
name. I didn't choose to in this case. Now

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I would like to enter some lines into this
file, and the lines will be numbered. I

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can ask for automatic numbering of the
lines. So we'll give a command number. $

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NUM and if I terminated the line at this
point, it would number them starting with

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one in steps of one. Simple one, two,
three, four et cetera. But I will indicate

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in this case starting with line one but
will use steps of three. All right. It's

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now asking for line one. And I will simply
enter some information. This is the time,

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and I misspelled the word. Let's look at
how we might make corrections here. One

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way is to delete the whole line and start
over. To delete a line, I use control with

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the letter N. This inserts a delete line
character into the line. If I like I can

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continue with, with the new line that I
would like to have go in at that point,

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and I'll do that in this case. And end of
line. Notice that since I asked for steps

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of three, it is now asking for line four.
Let me, put some more information in here.

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And I made another mistake. Well, again I
could use control N if I like, and this

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time I'll terminate the line at that
point. And I get an indication that the

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line was deleted. I didn't get the indic
ation in the previous case because I just

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continued with the new form of the line.
Well, let me put the line in again. And I

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made another mistake. Now, in this case I
really need to only backspace a character

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and continue. Let me backspace two
characters to show how that could work.

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The backspace is Control and the letter A.
If I get two of them, I have now back

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space twice. And I can start the word come
again. Notice that the teletype does not

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physically backspace as a typewriter does.
The backspace character is inserted in the

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line, and when the line is processed by
the computer, it is interpreted to delete

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the previous characters. We don't see that
on the teletype itself. So, I can add

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another line here. All right, and now, let
me turn off the numbering, so that I can

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begin to do some other things with it. I
can give dollar sign a number. End of line

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character. That turns off the numbering
and it's waiting for me to do something.

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Now, the file X1 is my active file in the
sense that whatever I do such as putting a

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line in, goes into the currently active
file X1. To protect myself from doing

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something inadvertently and damaging the
information in the file, I will release it

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from being the active file by giving the
command Release. Now, for instance, if I

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chose to put a line in like two I am
protected because I don't have any active

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file. Now, since we did do a fair amount
of modification for the information in X1,

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let us print out or list the information
in the file to see what actually got in.

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Dollar sign, list. I can give the full
name if I like, X1. Looks very good. Now,

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let me show how we can put a line in if we
want to make a modification. I can put a

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line in with a number like two which will
go in the right place. I could even use

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2.5. So, let us make X1 the active file
again and put a line 2.5 into that file.

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X1 was active the first time because that
was created with the Create command. I

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can't do that now. But I can make it the
active file by using a command Get. It's

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acknowledged, and now X1 is probably the
active file. Let me try line 2.5. The

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information in the line starts with the
character after the comma, the comma

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indicating the end of the line number.
Now, let's verify that it actually got in

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there. I don't want to list the whole file
X1, it could be a very long file. It isn't

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in this case. So, what I'd like to do is
list a part of the file. Let's say, all

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the lines. In the number range one through
five. There's a mistake, backspace, next

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one, one two five. Notice that the line
2.5 was inserted in the proper place

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according to its line number. And the end
of file comment here even though we didn't

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get line seven has to do with the fact
that the name X1(1,5) named a new file

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which was in fact made up of parts of an
old file. X1 lines one through five. Are

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in fact a kind of a logical file. And when
it came to the end of that file, it

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indicated end of file. There are other
ways to make new files out of old files.

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We can use a process called Explicit
Concatenation. To do that, let me, for

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example list a file made up of pieces of
old files. I will say, list. I have a long

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file who's name is EX. So, I will take
lines 25 through 50. Oh, that's too long.

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Let's back, cancel that out, 27. Now, with
the plus sign, I explicitly append to the

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end of the, of those lines or concatenate
to them. Line some additional lines. Let's

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say, lines 53 and 54. Notice that if it's
the same file again, I don't need the name

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EX again. Now, I will concatonate some
lines directly from my terminal. So, I

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need a name of my terminal as a file. We
use asterisk, source, asterisk. That is

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the name of my terminal as an input file.
And then I will, maybe take some more

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lines from file EX. If I just give one
number, it means all the lines from 100

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on. And that's a long file, and so in
fact, we will see a fair amount of typing

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at that point. In fact, that raises the
question, how do I interrupt somethi ng

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which is going on that I would like to
stop? There is a special button on the

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teletype called the Break Button. It is
located in various places on different

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models of the teletype. In this case, it
is right here. Now, when I want to

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interrupt, as we will see, whatever is
going on, I will push the break button. At

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that point, because of the way the
teletype is built, the keyboard locks. And

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I must, then, push a button which occurs
in another part of the teletype, called

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the Brake Release Button. This button will
light, and when I push it, it will then

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unlock the keyboard. Now, lets do it and
we'll see how the brake process works. I

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will now give the end of line character.
So, that the line I just typed will in

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fact go in. Line 25, 26, and 27. These are
lines from some computer program, 53,

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there was no line 54. It is now waiting
for lines from the file called Source. And

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so I must give a line. And since I'm
listing things on, on this terminal. When

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I give a line as input, it'll come right
back out and be listed, as if it were in

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that file. It's the first line in that
file. Well, now I have to have a way of

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saying that's the end of this file that's
coming from my terminal, and so there's a

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special character, Control C, for end of
file. Now, that's a character that went

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into the line. I must now still terminate
the line. And then I will get an

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acknowledgement that it's on in the file
and now it continues to line 100 of that

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old file, EX. That's an interesting line
and I know that this file is quite a long

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file with some programs in it and so now,
I will hit the break button and terminate

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what's going on there. I get a response
from the computer that attention was

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indicated. Now, I will hit the Brake
Release Button to pre-up the keyboard.

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Which is lighted, when I push it, it goes
out, and now I can do something from the

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keyboard again. The number sign indicates
that after an interruption by the break

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button, the system is ready to have me
tell it what to do ag ain. Now, I'm going

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to illustrate the use of one of our
language processors in the system. A

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language called PIL, P-I-L, for Pittsburgh
Interpretive Language. And PIL is stored,

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the processor for the language, is stored
in a file whose name is asterisks P-I-L. I

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will run that program, that is the PIL
program itself by using the run command

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and the name of the file in which the
program is found. I could indicate that

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the source. Of input for PIL, is from some
other file. And have it read that file

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directly. In this case, the sources of
input will be from my terminal. And so , I

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will not say anything about it, and it
will as we say default to the terminal. We

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will see the comment execution begins when
the loader finds that program and loads it

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and begins it, and now PIL itself is
identifying itself as ready to go. I will

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only introduce some of the features of the
language. A full description of the

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language, as well as information about
using the teletype, is available at the

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bookstores in a small booklet called
Introduction to PIL in MTS, Written by

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Professor Larry Flanagan of the Computing
Center. Now, let me illustrate some of the

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features of the PIL language, but only a
few of them. For one thing, I can ask for

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Numeric expressions to be computed easily
three + four - two should come out five,

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00:22:52,006 --> 00:23:05,715
fine. I can say type the square root of
4.12345. I can ask for certain

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trigonometric functions like the sign of
the square root of, notice I have a

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different way of writing square root here.
It's not completely free English however.

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And these are the only two ways. Now, I
can ask for, for instance, the value of x

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+ one. And, of course, I get my wrist
slapped because I don't know what X is.

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And so I can set, there's another PILl
language command, set X equal to three.

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And now I can ask for a type X, x, X -
one, for example. Okay. Now it's possible

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in PIL to build up a package of statements
into a program. And for that we give a

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line number., which is consists of a
number in front of a decimal point. That's

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called a Part Number, and then the Step
Number. I might say step 1.2 which I might

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give as the man Y and Z. Now , that line
was not executed immediately, because we

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have a line number, it indicates it to be
put away to become part of a package

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program. Let's make line 1.3, 5Y + Z, as
well as Y and Z, and then line 1.4, is,

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can we go to step 1.2. So now, we have a
program which will start off by demanding

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two numbers from me, it will type out
their sum and each of them, and go back

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and demand two numbers again. Now. In
order to actually carry out this

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computation, I have to say do that set of
instructions. Since all these began with

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one, this is called Part One. We could
have Part Two, etc. So I will say, Do.

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Part one. It's asking for Y, as we
expected. I'll say Y is equal to five.

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It's asking for Z. Z is equal to four. And
now the instruction to type the amount is

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there, and now it's back to beginning,
asking for another Y. 79 and we see we can

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do various things. Now, how do I stop
this, because it's always coming back to

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ask for more? Well, in PIL, I could give a
break. I could hit the break button, but

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in PIL, when it wants more information and
you have no more, you can use an asterisk,

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which uses the shift key and way up here
the asterisk, and some character, any

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character at all other than blank, I use X
usually. End of line, and that indicates

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to PIL, that I interrupted the program at
step 1.2 where it was asking for input.

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Incidentally, if I wanted to see what step
1.2 was out of some large program I could

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say type Part One, and it'll tell me what
Part One was. Well, there are various

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things we can do in this language. I will
illustrate one more. I can say four, and

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without a line number, it'll be executed
immediately. 4I equal to one from one to

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five by 2s, 5I + one. If it goes from one
to five by twos, it'll go in one, three,

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and five. I + one should be two 46. So
let's see if it is. And now PIL is wai

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ting for something else. Well, at this
point, I will stop illustrating PIL and go

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back to the MTS system. Which should be
careful to distinguish that I have been

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running a particular program in the
system. All of the file manipulation and

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editing and correction were at the level
of the system itself. If I am talking now

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to PIL, if I want to return to the system
to, for example, to sign off, I must go

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back up to level of the system itself. I
do that by telling PIL the command system.

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Execution terminates, and, we are now back
at the system. Let us review the commands

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we have had so far. I have a file which
has the various commands in them. And if I

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copy that file, we should see some that
we've seen, and there will be a couple

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that we have not yet seen. Sign on. Create
to create a file. Get to make a file

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active. Number to turn on the automatic
numbering, and a number to stop it.

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Release to get rid of an active file. List
to find out what's in a file. We have seen

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set and run. We have not yet used copy.
Although I used it to get this command

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out, this list of commands. But the, the
main use of copy is to make a copy of one

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file into another one. Perhaps, a
temporary file to be able to make changes

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in it. So, for example, I will make a copy
of the file X1. I will copy it to a

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temporary file, whose name will be minus,
something, minus J. Now, the minus sign

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indicates that this file is to be created
just because I've mentioned this now. And

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it will be destroyed when I sign off from
this terminal. Permanent files, whose

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names don't begin with minus, such as X1,
are not destroyed. I could come back next

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week and find X1 still intact. It takes a
little while to create a temporary file

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because there is checking to make sure
that I don't have one already by that

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name. It is not ready, and for example, I
will list just a line or two out of minus

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J to convince us that X1 was copied into
it, let's list lines. Oh, just line one.

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Fine. Now, minus J will be destroyed au
tomatically but well, before we get to

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that, let's copy -J back into X1. In case
we want them to, after making some

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changes, preserve it. Now, now if we
simply copy it back into X1, only the

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lines that arrived from the other file
from -J will be replaced. Any old lines

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will still be there. If I don't want to
have a mixture of old and new I will, do

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well to empty out the contents of X1,
before I copy the new, new form of it back

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in. And so, I will use a new command
called Empty X1. This doesn't destroy the

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file. It only erases any contents that it
has. And now, this is a very important

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00:31:02,856 --> 00:31:09,085
point. We don't like to destroy
information unless we are sure that it is

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00:31:09,085 --> 00:31:17,009
the right information to be destroyed. I'm
being asked to confirm that it is X1 that

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00:31:17,009 --> 00:31:24,077
I want to, to empty, in this case. I give
okay, and that is a positive confirmation.

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An exclamation mark would do, or O period,
K period will work. But anything else will

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00:31:32,073 --> 00:31:40,030
not. So now, X1 is in fact, emptied. It is
still there. If I wanted to completely get

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rid of the file, I would say Destroy, as I
will after we Copy -J back into it. That

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00:31:53,123 --> 00:32:04,133
is done. And now I would have a new copy
if I had made modifications to -J. Now, I

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00:32:04,133 --> 00:32:14,026
will say Destroy X1, it asks for
confirmation. I will say, okay. And now,

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00:32:14,026 --> 00:32:24,332
for instance if I say Get X1, well it says
Ready, but as soon as I try to put

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00:32:24,332 --> 00:32:36,270
something into it like that, it will
report, there isn't any. As soon as it

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00:32:36,270 --> 00:32:45,793
comes back, I will Sign Off from the
computer. I, I will say Cancel in this

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00:32:45,793 --> 00:32:53,558
case. There isn't any others that I'd like
to do. All right. Now, I will sign off

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00:32:53,558 --> 00:33:02,071
from the computer by issuing the command
Sign Off. And now, I will get some

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00:33:02,071 --> 00:33:11,088
information summarizing the session that
I've just finished. The time of going off,

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00:33:11,088 --> 00:33:21,553
the elapse time. We have used thirteen
seconds in this case of computer time. And

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then there's various other information.
The approximate cost of this particular

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00:33:31,181 --> 00:33:41,269
run was $3.20. This presentation has been
designed to make your work on the teletype

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terminals e asier. For a review of this
material, you may wish to view this

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00:33:48,891 --> 00:33:53,968
material again, or to actually try it out
on the teletype, if you have a computing

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00:33:53,968 --> 00:33:58,497
center number. If you have any questions,
ask your instructor, or someone in the

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00:33:58,497 --> 00:34:04,423
counseling room at the computing center.
» Your attention please. Since this film

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was produced, some changes have been made
in the MTS system. Three of which we now

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00:34:11,655 --> 00:34:19,042
call to your attention. First, to
backspace so as to delete a character.

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Instead of Ctrl + A, use Ctrl + H. Instead
of Ctrl + A, use Ctrl + H. Second, while

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Ctrl + Q may still be used to signal the
end of the input line, the Return key on

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00:34:35,335 --> 00:34:46,299
the right side of the keyboard may also be
used and it is usually more convenient.

280
00:34:46,299 --> 00:34:51,918
Use the Return key to end the line. Third,
when dialing in, if nothing prints on the

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00:34:51,918 --> 00:34:59,802
teletype, within a few seconds after the
telephone connection has been made, type

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00:34:59,802 --> 00:35:06,957
the word Go. Go. Followed by the Return
key. The word go, and the return key.

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Thank you.