There is NO DEFINITION.
Dot.
Yes, there is no single definition of mainframe. Everyone may use it's
own imagination.
Of course some definition may be less popular than other.
IMHO (note - this is OPINION), the most commonly used definition
NOWADAYS is: IBM System Z.
Note, there is nothing about security, capacity, etc. Just family of
computers, like POWER or Sun, or (former) VAX, etc.
Etymology of mainframe
(This is excerpt from my book, manual for "Introduction to z/OS and
mainframe" course)
In the old days computers were very big, occupied many cabinets. Those
cabinets were also called frames. There were no "single chip CPU",
instead we had Central Processing Complex or just MAIN frame.
The word does not contain any suggestions to advantages like
performance, capacity, reliability, etc.
Former mainframe world
In the old days there were several mainframe suppliers, however in most
cases the machines were not compatible. Different hardware, different
OS, different channels, different communications.
Examples were Burroughs, ICL, Siemens, Bull, Honeywell, RCA, etc.
Former classification of computers
Microcomputers - PC, Apple Mac
(usually) RISC machines (Sun, HP, AS/400, RS/6000, ICL K-server, Escala)
- minicomputers
(big) computers - ICL 1900, IBM S/390 (with predecessors and
successors), UNIVAC, GCOS, etc.
supercomputers - quite different from mainframes/big computers and quite
different uses.
Yes, every sentence can be corrected or complemented. No, it doesn't
matter. Because THERE IS NO DEFINITION of mainframe. :-)
--
Radoslaw Skorupka
Lodz, Poland
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