This is a brief introduction to basic concepts and commands for using the LCM+L's IBM 4361 midrange computer system.

The 4361 runs the VM/SP virtual machine operating system.

VM is basically two components:

• The Control Program (CP) which controls the real hardware and provides a virtual machine (VM) for each user, and
• The single user Conversational Monitor System (CMS) which runs in a VM to provide the user environment (shell to you UNIX/Linux types).

IBM has published an introductory document, The Basics of Using z/VM.¹⁾ This gives a short overview of VM in general.

The VM user environment has not changed extensively between VM/SP 5 and z/VM, but there are few differences to point out between the 4361 and the environment described in the document:

• The 4361 is a 32-bit machine with a 24-bit (16 megabyte) address space.
  • MVS/XA, MVS/ESA, and z/OS guests (all descendants of MVS) cannot run under VM/SP.
  • No supported version of Linux or Unix guests can run under VM/SP.
  • VM/SP does not have a POSIX shell or related utilities
• You cannot switch between sessions at the LOGON screen.
• VM/SP 5 only supports minidisks for storage; it does not support:
  • SFS (Shared File System)
  • BFS (Byte File System)
  • NFS (Network File System)
• VM/SP supports the CP TRACE command, but not as documented in the presentation. (Enter HELP CP TRACE.)
• VM/SP does not support the CP TERM MORE command.

Now go read the IBM introduction. We'll wait.

You can connect to LCM+L's 4361 with Secure Shell (ssh).

ssh ibm4361@tty.livingcomputers.org

Once you have connected to the 4361, you can follow the instructions on this page starting with the section “Log-on Procedure”.

The PA2 3270 terminal key (for clearing the screen) is mapped to Ctrl-A 2 (Control-A followed the number 2) when connecting with ssh.

(ssh is available as part of the OpenSSH package for MacOS, *BSD and Linux operating systems, or PuTTY for Microsoft Windows.)

The VM/CMS system was originally designed to be accessed from a 3270-compatible terminal. Today, since 3270 hardware is rare, you will probably use 3270 emulator software.

x3270 is a free open source software suite of 3270 terminal emulator tools by Paul Mattes and others. It includes clients for X11 (x3270; for Unix, Linux, *BSD, etc.), MS Windows console (wc3270), and others.

Download an appropriate package and follow the instructions to install it on your system.

On most platforms you can specific the model of terminal emulator if you start the program from the command line. The model is composed of two parts:

1. The model number:
   1. 3278 are monochrome terminals. These were the most common type when real 3270 terminals roamed the land.
   2. 3279 are color terminals. VM/SP has good support for them, and are generally preferred when using modern terminal emulators.
2. The model suffix, which specifies the screen size:
   1. 2 is the classic 80 columns by 24 lines.
   2. 3 is 80 columns by 32 lines.
   3. 4 is 80 columns by 43 lines. This is useful for editing.
   4. 5 is 132 columns by 27 lines. This is useful for reviewing listings.

Thus for a color terminal sized 80×43, the full model is specified as 3279-4.

You can login via x3270 from via a terminal window the X-Windows menus:

1. Using a xterm or other terminal window:
   1. run x3270 –model 3279-4 tty.livingcomputers.org 24
2. Using X Windows menus:
   1. In your X session, run x3270.
   2. From the Connect menu click Other….
   3. In the “x3270 Connect” window, enter the following Hostname: tty.livingcomputers.org:24
   4. Click Connect. (The host will automatically be added to the Connect menu for future sessions.)

You can also install and use the more limited text window version, c3270; this will be limited by the size of the window it runs in:

1. c3270 –model 3279-4 tty.livingcomputers.org 24

1. Run the wc3270 Session Wizard.
2. On the Overview menu, select “1. Create new session (new)”.
3. Enter the configuration parameters from the table below.
4. Answer “y” to “Create session file '…'?”.
5. Optionally, answer “y” to “Create desktop shortcut?”.
6. Return to the Overview menu and select “8. Quit (quit)”.

First things first:

• Figure how your terminal emulator sends PA2 to the host. For example, the default x3270 mapping is Alt-2. This is because …
• … Once connectted to VM, to clear the screen, use host key PA2. This clears all but the input area at the bottom of the screen.

You'll also need to know how your emulator sends:

• ENTER (usually your ENTER or RETURN key)
• PA2
• PF1 through PF12
• RESET (often Alt-R)
• ^ (Insert Mode) (by default, 3270 terminals overwrite)

Start your 3270 terminal emulator and connect to the LCM+L's 4361.

You'll be rewarded with a screen like the one below, which is the front end terminal controller emulator for the 4361.

Put an X on any device, and press ENTER. You'll be rewarded with the VM Login screen:

Note: If this icon, , on the bottom line of your terminal, it means you tried to input data when the cursor was not located in an input field on the terminal screen. Press TAB to move the cursor to the next input field.

Enter your Userid & Password (use TAB to move the cursor to the next input field), press ENTER and you're off to the races.

After you log-in, your terminal will look something like this:

The terminal screen is divided into four areas:

A: System output. Commands you input to CMS are echoed here, and all system output is printed.

B: User input. This is the only input area on the default CMS screen.

C: System status

D: Terminal status

When you see the ready prompt (Ready; T=0.21/0.38 02:40:57 in the screen shot above, but yours can be customized), type commands into the user input area followed by ENTER, and CMS will try to fulfill your every desire.

The system status area indicates the state of your CMS session and what kind of input the system is expecting from you. The following messages may be displayed:

Resources, including disk, are allocated by CP among users as disks and links defined by the user directory, a file maintained by the system administrator. Disks can be dedicated in their entirety to a single user²⁾, or divided into disks for smaller users. Such smaller disks are called minidisks. Common minidisks are listed below.

As noted above, access to others' disks are done by link definitions in the system directory. Each disk in the directory may have one or more link passwords. If a disk is that is not defined as attached to your VM has a password for a mode, you may link it via a user command.

A file on a CMS file system is described in three parts, separated by spaces. All three parts are required.

Like Windows, the function of a file on CMS is defined by its type. Common types are listed below.

As noted above, file modes consist of the letter of the disk the file resides on, and number further defining a file.

Enter HELP command at the command prompt on most of the commands below. Most commands can be abbreviated, and CP can usually be omitted.

In addition, compilers for the following languages are available: Assembler (ASSEMBLE), BASIC, C, COBOL, FORTRAN, PL/I (PLI). (Where not otherwise noted, the compilers are invoked by their language name.) Not all of those have HELP files.

For its environment, XEDIT is both an easy to use and powerful editor. It's primary lack is no cut-and-paste, but modern terminal emulators can do client-side pasting which is not visible to the mainframe.

However, this power does require a good explanation, so this humble author defers to IBM on the topic; see XEDIT Users Guide for z/VM for a proper overview of XEDIT.

Note: Most XEDIT examples show a prefix area with equal signs to the left of the screen, a scale across the middle of the screen, and the current line in the middle of the screen as well. The LCML4361 profile, which resides on the Y-Disk, changes this appearance to reduce the fixed “chrome”; it also moves the current line up, and provides line numbers in a right hand prefix area out of the way.

You can move current line back to the middle and turn on the left prefix area and scale by entering the following commands in XEDIT:

SET CURLINE ON M
SET PREFIX ON
SET SCALE ON 

You can permanently customize the appearance by creating your own PROFILE XEDIT A, or simply editing the file on the Y-DISK and changing the file mode to A (SET FMODE A) before you save it.

File of type EXEC or XEDIT can be one of three languages:

• Rexx (Restructured Extended Executor), released with VM/SP 3 in 1982, is a block structured, high-level programming language. The first line of a Rexx program on CMS must begin with a C-style comment (/* */).
• EXEC 2, released with VM/SP 1981, is an enhanced version of EXEC, with longer tokens, ability to communicate with commands such as GLOBALV and EXECIO, and other enhancements. The first line of an EXEC2 program must start with &TRACE.
• EXEC dates back to 1966 and the original CP-67 System, and based on even older facility for CTSS . It's famous for truncating tokens in strings to eight characters, which is rather annoying if your last name is “Cowlishaw”. All EXEC and XEDIT files which are not flagged by their first line as Rexx or EXEC2 programs are processed as EXEC programs.

See For Further Reading below for the primary IBM references and other resources on Rexx. The addition information on Rexx on the 4361 itself:

• Enter HELP REXX to get a basic feel of the language
• Browse the KENDRA XEDIT Y to see a sample of the code.

For help on the earlier scripting languages, enter:

• HELP EXEC MENU
• HELP EXEC2

The MENU is needed for EXEC but not the other languages because there is an EXEC command which, not surprisingly, runs EXEC files.

As of this writing, two modern (to the 1980's) compilers are installed on the 4361:

• C (GCC)
• VS FORTRAN Version 2 (FORTVS2)
• PL/I Optimizing Compiler (PLIOPT)

Older compilers, most dating to the original OS/360 era, are also installed:

• COBOL
• FORTRAN G (FORTRANG)
• FORTRAN H (FORTRANH)
• PL/F (PLIF)

All the compilers run TEXT (object) files, which need to be combined with run-time libraries and saved as executable MODULE files. Various sample scripts will do this for simple programs:

• GENCOBOL
• GENFORTG
• GENFORTH
• GENFORTV
• GENGCC
• GENPLIF
• GENPLIOP

For a more detailed example of linking a program and running it, see vm_cms_fortran

Rounding out the language processors are interpreters, which were primarily oriented towards educational environments:

• BASIC
• FORTH
• PL/C for CMS (PLCT)
• SNOBOL4
• WATFIV FORTRAN (WATFIV)

These do not generate TEXT files with object code, but instead run the translated programs immediately.

Most the links in section are PDF files, many cases scanned copies of the original IBM manuals loaded to the site http://bitsavers.org/.

Note: Where VM/SP Release 5 manuals are not available, other releases are used as listed. For release 6, most differences are minor and/or obvious, for example the new for release 6 Shared File System was supported. Usually, an appendix in each newer manual lists the differences from release 5.