CTSS: A quick tour using s709

We'll use my eliza-ctss repo to get set up as this automates several of the steps involved. You can also get the components directly from the s709 page and set it up following the instructions there - both methods will yield the same system.

You will need a Unix like environment that can compile C code, run shell scripts etc. You will also need a telnet CLI or GUI client.

Start by cloning the repo and changing into its directory. All commands will be run from there.

  $ git clone https://github.com/rupertl/eliza-ctss
  $ cd eliza-ctss

(Numbers in square brackets refer to notes below, do not enter these on your terminal.)

  $ source env.sh                    [1]
  $ make-binaries                    [2]
  $ make-disks                       [3]
  $ format-disks                     [4]
  $ install-disk-loader              [5]
  $ installctss                      [6]

1. Set up the path and environment variables needed. Run this before any other commands.
2. Compile the s709 and utility binaries, and place them into ctss/bin.
3. Create files in dasd/ representing the disk and drums needed for CTSS.
4. Format the disks and drums. You will be prompted to press Enter a few times and type q and Enter when done. This may take 60s.
5. Install a basic disk loader on the disks to prepare for the full CTSS install.
6. Install the base CTSS components on the disks.

  $ source env.sh
  $ runctss

This will start CTSS and begin accepting logins. The simulator window will show log in/out activity.

In another window, telnet to port 7094 on your local machine. Type login guest and at the password prompt type system.

$ telnet 0 7094
Trying 0.0.0.0...
Connected to 0.
Escape character is '^]'.
s709 2.4.1 COMM tty0 (KSR-37) from 127.0.0.1

MIT8C0: 1 USER AT 12/30/14  852.7, MAX = 30
READY.                                     
      
login guest
W 852.8
Password
 M1416     5 LOGGED IN  12/30/14  852.8 FROM 700000
 LAST LOGOUT WAS  12/25/14 1626.0 FROM 700000      
 HOME FILE DIRECTORY IS M1416 GUEST          
                                   
THIS IS A RECONSTRUCTED CTSS SYSTEM.
IT IS A DEBUG AND NOT FULLY FUNCTIONAL VERSION.
                                               
 CTSS BEING USED IS: MIT8C0
R .050+.000

Your two windows should now look like the image at the top of this post.

• CTSS communicates in upper case, but you can type in lower case and it will be translated to upper automatically.
• There is no prompt, but you will know CTSS is ready for input when it prints R followed by 2 numbers (which represent the CPU time and swapping time for the last command run).
• Delete will delete the last character and Control-U will kill a whole line. This is an affordance of the emulator; on a a real teletype you'd type # to delete and @ to kill; these keys still work as such on the emulator.
• Control-C will interrupt a program and Control-\ (backslash) will quit it.
• Commands are in the familiar format of the program name followed by parameters. Optional arguments are enclosed in brackets.
• When you enter a command, CTSS will first type something like W 1724.3. The W means you are waiting for the command to load and the numbers are the time of day the command started (using tenths of minutes after the decimal point).

CTSS has the concept of a Master File Directory containing several User File Directories, one for each user. It is not possible to make further sub-directories. There is the concept of a shared directory which we will look at in a later post.

To view the contents of your directory, type listf.

listf 
W 1305.9
        
     9 FILES    90 RECORDS
 NAME1  NAME2 MOD NOREC   USED
  CQA1    MAD 000     3 12/30/14
 HELLO    MAD 000     1         
PRIMES MADTRN 000     2
MYLISP  SAVED 000    77 12/26/14
  FACT   LISP 000     1         
DEFINE   LISP 000     2
 FFACT   LISP 000     1 12/13/14
PROCAL   LISP 000     2         
BOTTLE    MAD 000     1
                       

R .016+.016

You can give parameters to change the display order and select which files are printed. For example, to show MAD source code files in alphabetic order:

listf (sna1) * mad
W 1328.5
        
     3 FILES     5 RECORDS
 NAME1  NAME2 MOD NOREC   USED
BOTTLE    MAD 000     1 12/13/14
  CQA1    MAD 000     3 12/30/14
 HELLO    MAD 000     1         
                       

R .016+.016

File names have two parts, called name1 and name2, each up to six characters long. Note the first and second parts are not separated by a dot, so what we'd call "hello.mad" would be "HELLO MAD" on CTSS. The first part of the name is called name1, hence the parameter to sort by name1 is (sna1). As shown, you can use * as a wildcard.

You can print a file to the console with P. This will include some blank lines at the end so you will need to scroll up your terminal to see it.

p hello mad
W 1332.4
        

	 VECTOR VALUES HELLO = $12H HELLO WORLD*$
	 PRINT FORMAT HELLO                      
	 END OF PROGRAM    


         
R .000+.033

Let's compile and run the above file.

mad hello (list)
W 1333.7
LENGTH 00020.  TV SIZE 00003.  ENTRY 00011
R .016+.033

As the name2 of the file was MAD, we don't need to give it. If the file had been called hello mymad we'd have entered mad hello mymad.

The compile did not produce any errors. If you do a listf for files you will see two new ones.

listf hello *
W 855.3
       
     3 FILES     3 RECORDS
 NAME1  NAME2 MOD NOREC   USED
 HELLO    MAD 000     1 01/05/14
 HELLO    BSS 000     1         
 HELLO    BCD 000     1
                       

R .016+.016

The BCD file contains a listing of the compilation. The BSS file contains object code.

There is no separate linker step required to get this in a runnable state. Instead, the loader will bring this into memory and find any called routines. By typing LOADGO you can then run ut immediately.

loadgo hello
W 1335.0
EXECUTION.
 HELLO WORLD
  EXIT CALLED. PM MAY BE TAKEN.
R .166+.016

Type logout. The system will also log you off after a period of inactivity. You can start the telnet session again if you want to login again.

CTSS will support up to 30 simultaneous users, but note if you are already logged in with a certain user ID, you cannot start a second session.

It's important to shut down CTSS cleanly when finished to avoid corrupting its disks.

You will need to switch back to the main emulator window you started earlier - this cannot be done from the telnet session.

Execute the following, pressing Enter after each non Control-C line.

• Press Control-C
• Type ek 40017
• Type st
• Press Control-C
• Type ek 0
• Type st
• Press Control-C
• Type ek 40032
• Type st
• Type q and Enter to exit.

What is going on here? On the real IBM 7094 the operator would initiate shutdown by toggling in a value on the front panel (ek, for enter keys, in the emulator)

You can start CTSS again by running runctss as before.

If you forget to do the above, or your machine crashes, or if there are any problems starting CTSS again, all is not lost. Run this command to do the equivalent of a fsck or chkdsk.

  $ source env.sh
  $ salvagectss

You will need to type st a couple of times to start the machine. When the output says QUIT, type q.

The CTSS Programmer's Guide section AA.2 has a contemporary "Time-sharing Primer" showing nee users how to perform simple tasks.