IBM System/34

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IBM System/34 (model 5340)

The IBM System/34 was an IBM midrange computer introduced in 1977.[1] It was withdrawn from marketing in February, 1984.[1] It was a multi-user, multi-tasking successor to the single-user System/32. Most notably, it included two very different processors, one based on System/32 and the second based on older System/3. Like the System/32 and the System/3, the System/34 was primarily programmed in the RPG II language. One of the machine's interesting features was an off-line storage mechanism that utilized "magazines" - boxes of 8-inch floppies that the machine could load and eject in a nonsequential fashion. Borrowing mainframe features such as programmable job queues and priority levels, the System/34 ran on 64K of memory.

Physical appearance and requirements[edit]

The System/34 5340 System Unit resembled a huge washer-dryer in appearance, and was noisy, due to its internal cooling fans. It had several access doors on both sides. Inside, were swing-out assemblies where the circuit boards and memory cards were mounted. It weighed 700 pounds and used standard household 220V power. The system cost US$100,000-plus.

IBM abbreviations[edit]

IPL - Initial Program Load


APAR—Authorized Program Analysis Report


PTF - Program Temporary Fix

IBM would distribute bug fixes on diskettes called PTF diskettes. By applying PTFs, the user could address software problems. When the next release was issued (S/34's last release was Release 9 in 1981) the old PTFs were incorporated into the release update diskettes the user received, and the old diskettes became useless. Since PTFs were only temporary in the sense that they were superseded by later releases of SSP, using the name "PTF" was considered odd.

F1, I1, S1-S3, and M1.01 - M2.10[edit]

These are proper names given to system equipment.



SSP, The System/34 Operating System[edit]


Language compilers[edit]

The S/34 had five: RPG II, COBOL, BASIC, FORTRAN, and Assembler. RPG was cheaper, created compact code sizes, and became the best-seller. Cobol was popular in the business community. Fortran is not very practical for data processing purposes, and while Basic was nice, it was implemented as an interactive 40K session. Assembly language is efficient, but it is a little too easy to accidentally create a processor check on the System/34.



SDA - Screen Design Aid[edit]


SORT - The system sort utility[edit]




// RUN


SEU - Source Entry Utility[edit]


WSU - Work Station Utility[edit]


Terminals, displays, screens, workstations and monitors[edit]

An operator sat in front of a device that vaguely resembles today's PC, except the monitor was small, expensive (US$2,000), low-resolution (24x80) and the available colors were green and bright green. Colour screens (7 colours) arrived later.

For preparing data input diskettes, as a successor to card punches, there was a special workstation called a "dual display" (3742) which employed a system of mirrors to split a horizontally mounted screen into two 12x80 displays. Two users sat on either side of it with two keyboards and two diskette drives.

IBM colors[edit]

Before 1984, the 5251 monitor predominated - it was US$2,000 and what IBM called "dual color" (green and bright green). However, by 1984, the IBM 3180 terminal helped usher in the age of IBM Color - seven colors (pink, red, blue, yellow, green, white, and turquoise.) By 1984, the price of the 3180 terminals was under US$2,000, though there was a graphics-capable terminal. By 1986, there was another type of "color" monitor - instead of green, the displayed characters were yellow ("amber," in IBM-speak).

Programming IBM colors[edit]


The five lights[edit]








The 5251 and 5291 terminals used an 83-key keyboard with a similar key arrangement to the IBM PC 5150. Later 5250-compatible terminals used a 122-key or 102/103-key keyboard. There was a special terminal and keyboard for Katakana, a syllabary of the Japanese Language

Configuring devices[edit]


Printers and workstations had a series of binary switches known as "dipswitches" for configuration. The binary OFF settings, zero ("0") and one ("1") were used to switch back and forth internally. In U.S. English and UK English, the British use the pound sterling ("£") and the Americans use the dollar ("$"). A switch could be set up on printers and monitors where in the zero position the British value would display or print. In the one position the American value would display or print. .

Setting the address[edit]





Configuring using CNFIGSSP[edit]

The CNFIGSSP procedure was used to configure the system, including the devices. Each device is assigned a two-character ID. The first letter must be alphabetic; the second must be alphameric. The system also reserved certain IDs; the device can't be called I1 or F1, for example. I1 is the name of the diskette drive; F1 is what the system calls the hard drive (stands for "fixed disk," since it's not a removable disk pack.)




S/34s had two processors, the Control Storage Processor (CSP), and the Main Storage Processor (MSP). The MSP was the workhorse, based on System/3 architecture; it performed the instructions in the computer programs. The CSP was the governor, a different processor with different semi-RISC instruction set, based on System/32 architecture; it performed system functions in the background. Special utility programs were able to make direct calls to the CSP to perform certain functions; these are usually system programs like $CNFIG which was used to configure the computer system. These two processors worked in tandem.

Clock speed of the CPUs inside a System/34 was fixed at 1 MHz for the MSP and 4 MHz for the CSP. In today's PC-based world, the S/34 was the computational equivalent of a 16 to 20 MHz intel 80386 microprocessor.

Memory and disk[edit]



Typical System/34 offerings would include:


System security[edit]

There are three types of System/34 security: the badge reader that almost nobody ever bought, so it isn't discussed here; password security; and resource security.


The System/34 sign on looked like this:

* SIGN ON                                W1
* USER ID......... ________
* PASSWORD........ ____
* MENU (OPTIONAL). ______
* LIBRARY......... ________




Files and libraries[edit]

SSP provides for two different data objects called files and libraries. Files contain records, almost always with a fixed record length. Libraries contain programs which can reference and access these files. SSP contained more than 60 different commands that allowed operators to create, delete, copy, edit/change, and secure files and libraries.

Disk space metrics[edit]


Program sizes[edit]

Since the S/34 ran "16-bit" programs, the largest program that could be compiled and run was 64K. Most were not nearly that large. Since memory addresses were stored in 16 bits, a 64K program was often a giant monster RPG screen program with 3,000 lines of code, five or six files, and forty-odd array/table entries.


<<Read this section with caution; much more than 48K RAM was available on S/34; the process to squeeze a program into a smaller executable size was called overlaying.>>



SPOOL is an acronym for Simultaneous Peripheral Operations On Line.

The need for spooling[edit]

Computer printers are slow. On the S/34, computer programs could write data to the printer much faster than the printer can print and there can be more than one program writing to a printer at the same time.

How spooling works[edit]




Forms numbers[edit]

When the operator prints paychecks, it is important that paycheck information printed on checks forms and not on plain paper; likewise, a regular printout should never print on expensive check forms. Therefore, forms numbers were created. A forms number is a one-to-four-character alphameric field that programs and operators use. Programmers use the PRINTER OCL statement as follows:



SYS-1404 OPTIONS (012 )


Forms alignment[edit]

The expensive check forms must be perfectly aligned or all of the numbers won't fit in the little boxes. Therefore, an alignment can be performed using the PRINTER OCL statement:



SYS-5825 OPTIONS (012 )


Jobs and job queues[edit]


Sometimes a needed report should be run in the background so as not to delay the users. If the parameters of the report are defined, it shouldn't occupy the user's time or occupy that valuable area on the CRT. For this reason, the Job Queue was invented. Imagine the program standing in line waiting to use the computer processor. A job queue has a size (the number of jobs that can be in line) and a value for concurrency (how many lines there are, or, more accurately, job queue jobs that can run at the same time.)





Program attributes - MRTs, SRTs, NRTs and NEPs[edit]

MRT = Multiple Requestor Terminal program. SSP could attach up to 7 terminals to a program at once. Any operator could start the program at their terminal, then other operators' terminals would be attached when they selected the same program. The maximum number of terminals to be serviced was controllable by the programmer.

SRT = Single Requestor Terminal program. Not a MRT.

NRT = No Requestor Terminal program. Started at a terminal, the NRT releases the requesting terminal and continues. This is similar to an MS-DOS TSR (Terminate and Stay Resident) program. By definition, any program that was EVOKEd or submitted to the JOBQ was a NRT.

NEP = Never Ending Program. This was typically an interactive MRT program that would wait after all terminals disconnected until some terminal reconnected, avoiding initiation overhead. This was commonly used to allow large programs to be implemented as a chain of small programs that would pass the terminals from one to another while remaining ready to continue processing for other terminals and/or subsequent transactions. NRT programs could also be NEPs if written to loop and wait for some condition indicating there was work to be done. NEP programs normally did not end until system shutdown, unless written to recognize some special terminate condition.

Other object types[edit]





Screen formats generated object code.





Non-programmers use of the computer[edit]

The non-programmer could create a short sequence of file and input specifications and store them as a source member. A component called Data File Utility could then be used to generate on-screen displays for creating and edit files and print reports. It was not quite the equal of say, Access 2007, but in twenty minutes a file and a report could be designed Alternatively, define the data files and have the system generate a simple report program, using the Create Auto Report command.

Popular System/34 applications[edit]





The Britz Word Processing System was a general-purpose text editor that had mailmerge, label, and basic file editing capabilities.

System/34 magazines[edit]


Migrating to the System/36[edit]

From 1984 until the mid-1990s, businesses began the process of shutting down their S/34s and moving to twice-as-powerful System/36s. The two machines were not object-code compatible; but source code from a System/34 would compile and go on a System/36.


See also[edit]


  1. ^ a b IBM Corporation. "System/34". IBM Archives. Retrieved December 4, 2012. 


Further reading[edit]

  • Massoglia, Charlie. Everything You Always Wanted to Know About the System/34 But Nobody Told You. 
  • Massoglia, Charlie. Writing and Using System/34 Procedures Effectively. 
  • Lee, Merikay. Everything You Always Wanted to Know About POP But Nobody Told You. 
  • Massoglia, Charlie. System/3 and System/34 Disk Sort as a Programming Language.