The
System/38 was a
midrange computerMidrange computers, or midrange systems, are a class of computer systems which fall in between mainframe computers and microcomputers.The class emerged in the 1960s and machines were generally known at the time as minicomputers - especially models from Digital Equipment Corporation , Data General,...
serverIn the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the "server" performs some computational task on behalf of "clients"...
platformA computing platform includes some sort of hardware architecture and a software framework , where the combination allows software, particularly application software, to run...
manufactured and sold by the
IBMInternational Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
Corporation. The system offered a number of innovative features, and was the brainchild of
IBMInternational Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
engineerAn engineer is a professional practitioner of engineering, concerned with applying scientific knowledge, mathematics and ingenuity to develop solutions for technical problems. Engineers design materials, structures, machines and systems while considering the limitations imposed by practicality,...
Dr. Frank SoltisFrank Gerald Soltis , an American computer scientist, was IBM's Chief Scientist for the System i computers. Based on his Ph.D. research, his pioneering architecture of technology-independent machine interface and single-level store has appeared in these eight generations of IBM hardware: ...
. Developed under the code-name "Pacific", the System/38 was commercially available in August 1979.
History
System/38 was a descendant of the abandoned
IBM Future Systems projectThe Future Systems project was a research and development project undertaken in IBM in the early '70s, aiming to develop a revolutionary line of computer products, including new software models which would simplify software development by exploiting modern powerful hardware.- Background and goals...
, which had been designed as the replacement for the System/360 and System/370 mainframe architectures. System/38 offered more capacity than the previous IBM computer system,
System/34The IBM System/34 was a minicomputer marketed by IBM beginning in 1978. 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...
. Somewhat confusingly, System/38 chronologically preceded
System/36The IBM System/36 was a minicomputer marketed by IBM from 1983 to 2000. It was a multi-user, multi-tasking successor to the System/34. Like the System/34 and the older System/32, the System/36 was primarily programmed in the RPG II language...
which was a successor to the System/34.
System/38 was superseded by the AS/400 (which also supported System/36 data & programs, at least to some extent). The AS/400 evolved into the
iSeriesThe IBM System i is IBM's previous generation of midrange computer systems for IBM i users, and was subsequently replaced by the IBM Power Systems in April 2008....
, which in turn evolved into the
System iThe IBM System i is IBM's previous generation of midrange computer systems for IBM i users, and was subsequently replaced by the IBM Power Systems in April 2008....
. The System/38 legacy lives on in the enterprise-class
IBM POWER SystemsPower Systems is the name of IBM's Power Architecture-based server line.Before the Power Systems line was announced on April 2, 2008, IBM had two distinct Power-based lines: the System i running IBM i - and the System p series running AIX or Linux.- History :IBM had two discrete Power Architecture...
server which superseded System i in 2008.
Features
The System/38 had
48-bitComputers with 48-bit words include CDC 1604 and BESM-6.The IBM AS/400, in its CISC variants, is a 48-bit addressing system. The address size used in logical block addressing was increased to 48 bits with the introduction of ATA-6....
addressing, which was unique for the time, and a novel database-like storage schema. The operating system of the System/38 was called CPF, for "Control Program Facility". (CPF is not related to
SSPSystem Support Program was an operating system for the IBM System/34 and System/36 minicomputers. SSP was a command-based operating system released in 1977, the days of CP/M, DOS, and the original UNIX.- History :...
, the operating system of the IBM System/34 and System/36.)
The System/38 also had security built in as part of its architecture. Each object or library could have access controlled on a user-by-user basis. This has been continued and expanded throughout the AS/400 and iSeries computer lines.
Languages supported on the System/38 included
RPG IIIRPG III is a dialect of the RPG programming language that was first announced with the IBM System/38 in 1978.Unlike predecessors, RPG III uses external file descriptions, which means that disk files are built and RPG III programs are attached to them at compile time. Some other noteworthy changes...
,
COBOLCOBOL is one of the oldest programming languages. Its name is an acronym for COmmon Business-Oriented Language, defining its primary domain in business, finance, and administrative systems for companies and governments....
,
BASICBASIC is a family of general-purpose, high-level programming languages whose design philosophy emphasizes ease of use - the name is an acronym from Beginner's All-purpose Symbolic Instruction Code....
, and
PL/IPL/I is a procedural, imperative computer programming language designed for scientific, engineering, business and systems programming applications...
. The operational control language of the System/38 was called CL, for "Control Language". CL programs, similar in concept to
shell scriptA shell script is a script written for the shell, or command line interpreter, of an operating system. It is often considered a simple domain-specific programming language...
s, could be
compiledA compiler is a computer program that transforms source code written in a programming language into another computer language...
and executed
nativelyThe term native mode or native code is used in computing in two related senses.*to describe something running on a computer natively or in native mode meaning that it is running without any external support as contrasted to running in emulation....
.
Data Storage
In most computers prior to the System/38, and most modern ones, data stored on disk was stored in separate logical
filesA computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...
. When data was added to a file it was written in the sector dedicated to this, or if the sector was full, on a new sector somewhere else. In the case of the S/38, every piece of data was stored separately and could be put anywhere on the system. There was no such thing as a physically contiguous file on disk, and the
operating systemAn operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
managed the storage and recall of all data elements.
Hardware
In hindsight, the System/38's architecture was probably too demanding of the hardware of the era. When first launched, it struggled under the overhead of the software and operating system, which consumed almost 60 MB on disk, a vast sum at the time, leading some wags to suggest that the pre-announce code name for the series, PACIFIC, was actually an acronym meaning
"Performance Ain't Critical If Function Is Complete". Decades later, the same software, originally dismissed by some critics as a momentary aberration, runs better than ever on many thousands of modern systems within commercial and government enterprises of all types and sizes.
Distinctions
System/38 and its descendants are unique in being the only existing commercial computers with
capability-based addressingIn computer science, capability-based addressing is a scheme used by some computers to control access to memory. Under a capability-based addressing scheme, pointers are replaced by protected objects that can only be created through the use of privileged instructions which may only be executed by...
. (The earlier
PlesseyThe Plessey Company plc was a British-based international electronics, defence and telecommunications company. It originated in 1917, growing and diversifying into electronics. It expanded after the second world war by acquisition of companies and formed overseas companies...
250-History:Manufactured by Plessey company plc in the United Kingdom in 1970, it was successfully deployed by the Ministry of Defence for the British Army Ptarmigan project and served in the first Gulf War as a tactical mobile communication network switch....
was one of the few other computers with capability architecture ever sold commercially). Capability-based addressing was removed in the follow-on AS/400 and iSeries models.
Additionally, the System/38 and its descendants are the only commercial computers ever to use a machine interface architecture to isolate the
application softwareApplication software, also known as an application or an "app", is computer software designed to help the user to perform specific tasks. Examples include enterprise software, accounting software, office suites, graphics software and media players. Many application programs deal principally with...
and most of the operating system from hardware dependencies, including such details as address size and register size. Compilers for System/38 and its successors generate code in a high-level instruction set (originally called MI for "Machine Interface", and renamed TIMI for "Technology Independent Machine Interface" for AS/400). MI/TIMI is a virtual instruction set; it is not the instruction set of the underlying CPU. Unlike some other virtual-machine architectures in which the virtual instructions are interpreted at runtime, MI/TIMI instructions are never interpreted. They constitute an intermediate compile time step and are translated into the processor's instruction set as the final compilation step. The MI/TIMI instructions are stored within the final program object, in addition to the executable machine instructions. If a program is moved from a processor with one native instruction set to a processor with another native instruction set, the MI/TIMI instructions will be re-translated into the native instruction set of the new machine before the program is executed for the first time on the new machine.
The System/38 also has the distinction of being the first commercially available
IBMInternational Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
Midrange computerMidrange computers, or midrange systems, are a class of computer systems which fall in between mainframe computers and microcomputers.The class emerged in the 1960s and machines were generally known at the time as minicomputers - especially models from Digital Equipment Corporation , Data General,...
to have a RDBMS integrated into the operating system.
Series
The System/38 was nearly called the System/380, and the AS/400 was nearly called the System/40.
Sales
IBM sold an estimated 20,000 System/38s within the first five years of availability, according to articles published in industry magazines NEWS 34/38 and Midrange Computing. Although billed as a
minicomputerA minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...
, the S/38 was much more expensive than IBM's established best-selling System/34, and its replacement, the System/36. Of equal importance was the difficulty of upgrading from - say - a System/34 to a S/38. Although the machines had some similarities, such as twinax peripherals and RPG
programming languageA programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
s, in reality they were very different. IBM tacitly acknowledged this by bringing out the System/36 - an upgraded System/34 - after the launch of the S/38.
In the marketplace, IBM thus found itself with three overlapping, but incompatible, ranges. The System/34/36, the System/38 and the mainframe /360 architecture (that the System/38 was originally designed to replace).
Digital Equipment CorporationDigital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
, at that time one of IBM's main competitors, was able to exploit this by offering a wide range of products based on a single architecture. IBM's counter to this, the 9370 or 'baby mainframe', was a commercial failure.
The S/38's advanced operating system lives on with IBM's AS/400. Realising the importance of the thousands of lines of 'legacy code' (programs) written, 'AS' stands for 'Application System'. Great efforts were made by IBM to enable programs originally written for the System/34 and /36 to be moved to the AS/400. The AS/400 was replaced by the iSeries, which was subsequently replaced by the System i. In 2008, the System i was replaced by the
IBM POWER SystemsPower Systems is the name of IBM's Power Architecture-based server line.Before the Power Systems line was announced on April 2, 2008, IBM had two distinct Power-based lines: the System i running IBM i - and the System p series running AIX or Linux.- History :IBM had two discrete Power Architecture...
.
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