NCAR/TN-1 78+1A NCAR TECHNICAL NOTE I a- l iI October 1981 Interactive Computing on the IBM 4341 SCIENTIFIC COMPUTING DIVISION 4 NATIONAL CENTER FOR ATMOSPHERIC RESEARCH BOULDER, COLORADO Interactive Computing on the IBM 4341 Table of Cmtents UISAPVm 1 THE IBM 4341 COMPUTING SYSTEM ......................................... 1-1 The Hardware ..................................................- Virtual Machine Concepts.................................... - VM/370.................................. 1-2 Conversational Monitor System (CMS).................................. 1-5 Virtual Devices Under CMS ............................................. 1-6 GETTING STARTED ON THE IBM 4341 ......................... ........... .2-1 Understanding CMS ..................................... 2-1 CMS Virtual Machine ................................... 2-1 Communicating with VM/SP ............ 2-2.............2-2 Getting Commands Into the System...................................... 2-5 Formatting the Virtual Disks........................................ 2-9 Profile EXEC...o ..... ............................................ 2-10 Getting Acquainted with CMS ........................... ......... 2-10 Virtual Disks.... 2-14 Other Helpful Information................................ ......... 2-18 CYUATPKR 3 THE HELP FACILITY .................................... 3-1 Introduction ......................... ........... ..........3-1 Using the HELP Facility. ...................................3-1 Issuing the HELP Coamand............................................3-2 Menus....................................3-5 Perusing HELP Files................................................ 3-6 Using the PF Keys................................ .... ... 3-7 How to Create HELP Files..................................... 3-10 Formatting the HELP File............................................. 3-16 Related Publications..................... ........... 3-24 CHAPER 4 EDITING ON THE IBM 4341 ................................................. 4-1 Introduction .......................... 4-1 The IBM 4341 Full-Screen Editor .................................... 4-3 Using Program Function (PF) Keys ................................ 4-8 Scrolling Backward and Forward .................................... 4-10 Using PREFIX Subcommands.......................................4-12 Moving Through A File .......................................... 4-17 Making Changes in a File....................................... 4-18 Ending an Editing Session ....................................... 4-24 Learning More About the Editor...4-31 The IBM 4341 Line Editor ....................................... 4-35 Entering Data... .............................................. 4-36 Column Pointer................................................. 4-37 Line Pointer...................................................4-38 Making Changes in a File...........................4-41 Ending an Editing Session ................................... 4-53 Using Special Characters....................................4-59 CHAPT3R5 IBM 4341 VM/SP CCOMMAND LANGUAGE FACILITY .................................. 5-1 EXEC 2................................................... 5-1 EXEC 2 User Variables ................................................5-2 Variable Assignment Statements .................... 5-4 EXEC 2 Control Statements ...................................... 5-4 Logic Flow ............................. 5-5 Processing Flow ....................................................... 5-7 Interactive Data Passing .............................................. 5-9 Profile XEDIT ..... 5-11....................................... NCAR .EXECs.......................\\\ \\ \\ 5-11 References ...........................................................- References.5-13 1 6 RUNNING AND DEBUGGING JOBS ON THE IBM 4341 ....... 6-1 Introduction..........................................................6-1 Files Used and Created by the FORTRAN Process ........ 6-1 Running a Simple FORTRAN Job ...................... 6-2 Changing File Characteristics ........................... 6-4 More Sophisticated FORTRAN Programming ........ 6-5 Using IFTRAN ........ 6-10 Assembler Language Programming ......................... 6-10 Debugging on the IBM 4341... 6-10 FORTVS FORTRAN Warnings .................................... 6-13 Error Messages ................................... 6-14 How to Submit a Job to the CDC 7600 ............................. 6-14 Submitting a Job to the CRAY-1 from the IBM ..................... 6-15 Appendix A: IBM Commands Appendix B: tNAR EXECS and Utilities Appendix C: Keyboard Templates CIMPB 1: E 1M 4341 SZSIETPI The SCD computing system is complex, and it is difficult to disguise that complexity without impairing function. The IBM 4341 system is flexible; it is possible therefore to develop same elegance in the user interface while re- taining full user access to all system features. Cbnfifquration The IBM 4341 configuration installed at NCAR has a cen- tral memory of 4 megabytes, 3,997 megabytes of disk storage, and 6 magnetic tape drives with 4 at 6250/1600 bpi (200 ips), 1 at 1600/800 bpi (200 ips), and 1 seven- track 556/800 bpi (125 ips) . A card reader (800 cpm) and line-printer (1200 lpm) are also installed. There are two communications controllers, an IBM 3705 and an IBM Series/l. The 3705 handles bisynchronous communi- cations with remote IBM 3270 series controllers, comput- ers and terminals and asynchronous communications with terminals. The Series/1 is used to interface a variety of local asynchronous ASCII CRT terminals to the system. The Series/I adds some intelligence to the work of these terminals, making them look to the 4341 like IBM 3270 type terminals. Among other things, this enables users to take advantage of the full-screen editing capability of the system editor. All communications lines, both local and remote, are phy- sically connected to the GANDALF PACX IV. When communi- cation with the IBM system is initiated, either by RJE call up or by the initial interactive log-on message, the GANDALF connects the line to an appropriate port on the 3705 or Series/l. If no such port is available, the re- quest for access is queued and an appropriate message re- turned to the user. Note: After ten minutes of inac- tivity the PACX will automatically disconnect the port. Texmnals Several varieties of interactive terminals in the NCAR Available Mesa Lab are held available for use by visitors and by NCAR staff without their own terminal. Some of these are located in Room 4A , the Visitor Area. VIRcUAL MACHIN VEI EPL In all modern machines of capacity greater than the smal- lest of miniccmputers, the operating system facilitates multiprogramming, i.e. the concurrent sharing of system resources among several programs, but with only one pro- gram in control of the central processor (CPU) at one time. The determination of when each of the concurrently active programs gets control of the CPU is a complex pro- cess. However, the process is one which maximizes the productive use of the CPU, and other resources, while minimizing the elapsed wall-clock time for each program 1-1 to run to completion. For obvious reasons, multi- programming is frequently referred to as "time-sharing". IBatc and Computer programs can be divided into two classes, batch Interactive and interactive. Programs running in batch mode normally Pr ass run from beginning to end without the need for operator intervention, except perhaps for the mounting of tapes and similar activity. Programs running in interactive mode, as the term implies, are often characterized by a high degree of information exchange between the program and the user of the program, via an interactive terminal of some kind. Most modern computers have time sharing operating systems that facilitate concurrent execution of both batch and interactive programs. (Our CRAY-1 is an exception.) One must be careful not to use the term "time-sharing" when meaning interactive computing. Time-sharing can oc- cur without interactive programs running and vice-versa on small computers! W/370 IBM's Data Processing Division has implemented multi- programming in its computers in a way that is unique among U.S. hardware manufacturers. In addition to pro- viding a multi-programming operating system, IBM has tak- en the view that, in principle, each program would bene- fit from being run in a separate "computer" which would be configured precisely to the needs of the program. This is an extreme position and physically unrealistic. However, the idea is expressed in the Virtual Machine operating system, VM/370, which was developed for the IBM 370 series of machines in order to faciltate the further development of operating systems. This operating system supervises the operation of a number of "virtual machines". These machines can be batch machines, each with its own input and output queues in "virtual card readers" and "virtual punches or printers" respectively. The various batch machines may operate at different exe- cution priority levels. In addition, a unique "virtual machine" can be created for each interactive user. Each user may have a "virtual configuration" tailored to his particular requirements. All these virtual machines, of course, must be accommo- dated on the same real computer, and the characteristics of the various virtual machines are restricted by the limitations of that hardware. The concept of virtual storage, in which central memory overlays are handled by the operating system and are