IBM System/34

The System/34 ( S/34 also ) was a minicomputer architecture of IBM. It was introduced in April 1977 as a cheap alternative to the mainframes of the S/370 series. It was the successor to the System/32 and System/36 and the precursor of the smaller sister of the S/38 system. The S/34 served as a multi-user computer for departments and small businesses and was produced until February 1985.

Hardware

The memory capacity was a maximum of 256 kilobytes of RAM. The S/34 could be operated in the basic setup-two and by extension module with four disk drives, each with 64 megabytes. Was required to operate a connected and ready for operation chain printers as a system printer. His absence made ​​the operation of the S/34 is not impossible, but it was acknowledged at the start of the system with an answering subject error message. The backup was made exclusively via floppy disks to 8 ". Depending on the version of S/34, there were three individual feeds or two additional slots for magazines with ten floppy disks.

To the system maximum of 14 terminals could be connected with the type 5250 Twinaxialkabeln. At one strand devices could be connected to 7, which were connected in series one after the other. To this end, each terminal had an input and output. The terminal had to be terminated. The terminal on the first string in the first position with logical address 0/ 0 was the control or system console operator and administrators could be where the error messages from the operating system SSP, the so-called System Reference Code ( SRC) read and possibly answer. Here was also the entire control of the other S/34 including the monitoring system boot ( Initial Program Loading, IPL) and the reorganization of the plates ( Compress ).

Operating system and programming

The system was divided into four parts:

• The basic operating system SSP in a protected, accessible only to IBM technician with special floppy area;
• The data stored in libraries system programs of the SSP and, optionally, additional routines such as compilers, program generators, etc.;
• The data stored in libraries application programs (source code and machine programs );
• The sequential, direct, or simply indexed data files.

The proprietary operating system SSP appeared in nine versions. It had a general menu controls which are much more userfriendly made ​​the S/34, despite the significantly lower compared to the S/38 functions. So you could select commands from a menu structure, which is not so savvy administrators and users easier particularly complicated functions. Was programmed on the System/34 OCL (Operating Control Language ) as a control language and RPG or Cobol rare as a programming language.

For this purpose, the tools SEU ( Source Entry Utility) as a single line editor for the source code and SDA ( Screen Design Aid) as a design tool for screen masks were available. Furthermore, a as POP ( Programmer and Operator Productivity Aid) designated aid offered, a full- screen editor ( fullscreen editor, FSE) included. It made it possible to call many functions necessary for developers of the system of special menus and control programs. Furthermore, generators were available that allowed the simple dialogue processing or rapid expression of data files.

In practice, it was often necessary to perform a compress for the reorganization of plates, similar to today Defragment in Windows PCs. This vacant areas of the disk were grouped into larger blocks, so that the operating system could have this place again, since new data to be written could be written only into suitable blocks. This often lasted several hours.