IBM System/38
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The IBM System/38 was a minicomputer. It was a precursor to the AS/400 which was later called a series of names, AS/400e, eServer iSeries, iSeries 400, System i5, and most currently, System i. This was the brainchild of IBM engineer Dr. Frank Soltis. Introduced in 1978 and commercially available in August 1979, it followed the System/34 and was actually prior to the System/36. It was also a descendant of the fabled IBM 'FS' project, which was designed to be a follow-on/replacement for the System/360 and System/370.
The System 38 was something like a generation ahead of its time. Not least it had 48-bit addressing which otherwise didn't become more generally available for another 20 years. It also had relative-addressing; for everything. This was most obvious in terms of the storage. Before this time data stored on disk had been stored in physically separate files. Thus, when data was added to a file it was written in the sector dedicated to this or – if this was full - on a new sector somewhere else. In the case of Pacific, as S/38 was code-named, every bit of data, and indeed every element within each piece of data, was stored separately and could be put anywhere on the system. There was no such thing as a physically continuous file. Only the operating system could track where the data went. What was more, the machine itself was relative. Thus, in theory, it was possible to start processing an instruction in London, continue it a fraction of second later in on a machine in Los Angeles and finish it on one in Tokyo; without the user noticing any difference whatsoever as the machine kept track of this. In practice this was never implemented, but it was indicative of the incredible power of the machine. Thus the very powerful operating system had everything that every system designer might have wanted.[1]
As it turned out, it was a little too far ahead of its time for the hardware. Eventually, a decade, later it ran very powerfully indeed; as the hardware caught up with it. But when it was first launched it struggled. At least the hardware available at the time struggled to run the overhead of the software. There was, indeed, an enormous software overhead; something like 60 MB for the main programme, which was truly gigantic for the time.[2]
As usual with IBM there was a master plan for a whole range of machines. There were very small machines to take over from the System/32 and System/34, and very large machines to handle DP division applications. As was also usual with IBM, most of these machines were never actually launched. Certainly the smaller machines were never launched, since the hardware had enough problems keeping up with the software even on the medium-sized machines.[3]
The System/38 was nearly called the System/380, and the AS/400 was nearly called the System/40.
System/38 and its descendants are unique in being the only existing commercial capability architecture computers. The earlier Plessey 250 was one of the few other computers with capability architecture ever sold commercially. Additionally, the System/38 and its descendants are the only commercial computers ever to use a machine interface architecture to isolate the application software and most of the operating system from hardware dependencies, including such details as address size and register size. In addition, the System 38 was the first system to use Single-Level Storage (SLS), where the entire memory space is linear and every I/O device and memory is mapped to a virtual address. A better term might be uniform addressable storage. As objects (files, programs, control blocks, directories, and so on) are created, they are allocated disk space and are assigned a range of virtual addresses. These virtual addresses are used by the operating system to address the object data directly.
The System/38 also has the distinction of being the first commercially available IBM server to have a RDBMS integrated into the operating system.
IBM sold an estimated 20,000 S/38s within the first five years of availability, according to articles published in industry magazines NEWS 34/38 and Midrange Computing. Because S/38 was very much more expensive than S/34 and S/36, not as many units were sold, but the operating system was extremely advanced and was retooled into the AS/400. The iSeries computers were still being sold in 2006.
The advanced operating system of the System/38 was called CPF ("Control Program Facility.") CPF is not related to SSP, the operating system of the IBM System/34 and System/36.
Languages supported on the System/38 include RPG III, COBOL, BASIC, and PL/I. The operational control language of the System/38 was called CL ("Control Language"). CL programs are compiled.
