Transcript The Evolution of S/390

The Evolution of S/390
To understand the System/390 family of products, it is useful
to review a bit of history. On April 7, 1964, IBM announced
System/360 family of computers. The “360” in the name
referred to all points of a compass to denote the universal
applicability, wide range of performance and price, and the
“whole company” scope of the development effort.
The System/360 Architecture owes ist existence to the
genius of three scientists ,Gene Amdahl ,Gerry Blaauw
,Fred Brook sand to the then vice president of development
,B.O. Evans and his team who made it happen.
Although the System/360 remained unchanged for six years, just
six months after its introduction, IBM executives began to plan for
systems that would exploit the emerging Monolithic Circuit (MLC)
technology. By the end of 1965, a draft document defining a new
family of computer systems, called “NS” for New Systems, was
complete. The New Systems were to be based on monolithic
circuit technology and an extended System/360 architecture to be
called System/370. The System/370 architecture preserved
upward compatibility with application programs written for the
System/360 architecture. During the development of System/370
family, IBM recognized the need to expand the amount of main
storage available to application programs. This need led to virtual
memory which was publicly announced in August 1972 along with
the System/370 Models 158 and 168.
The Models 158 and 168 brought the multiprocessing
configuration to the System/370 family. Additional main storage
support came with the System/370 Extended Architecture (370XA), announced in 1981 and first shipped in 1983.
The next advance in the architecture came in 1988 with the
introduction of the Enterprise System Architecture/370
(ESA/370). This architecture again improved virtual storage
addressing by adding access registers, which allowed access to
another form of virtual storage, called data spaces. Data spaces
allow more data to reside in main and expanded storage,
reducing I/O and improving throughput.
In September 1990 IBM introduced the Enterprise System
Architecture/390 and the ES/9000 System/390 family of
computers. The ESA/390 includes ESCON and sysplex. In
1994 IBM announced extensions to the System/390 family
including additions to the ES/9000 line, which further exploit
these features, and introduces new, scalable, System/390
parallel processing computers in a Parallel Sysplex
environment. For IBM, two new computing directions are set
with this announcement. Complementary metal oxide
semiconductor (CMOS) technology is introduced as a
building block for very large computers, complementing
bipolar technology; and computers targeting specific
application environments -- rather than the full, generalpurpose environment- are introduced.
Architectural Integrity - Backward Compatibility
Assuming no I/O conflict, IBM guarantees that binaries
produced for 1965 machines will run
unchanged on todays servers.