You might want to do a quick memory refresh. <G> MVCL was a 370
op-code; 360 only had the MVC. <Big G>
-------------------------------<snip>--------------------------
Sometime ago I read a question from [EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>
if a sharp sudden unexpected pain would often result in a verbal response? Now Mr.
Bain from a company with ISAM in its name wonders about where the mainframe will be
in 10 years.
I wonder how familiar Mr. Bain is with what ISAM is, its history, and its so called
"death"?
Could not resist taking a peek at the ISAMgroup web site and discovered the
company maintains a proprietary data store (database) that allows them to
assist Mainframe sites with Software Asset Management and has been doing so for
10 years.
Hope I am not the only one who sees the humor in this.
ISAM or Indexed Sequential Access Method was about the second access method
produced by IBM for data storage and retrieval especially for new fangled
devices called disk drives sometimes known as DASD (Direct Access Storage
Devices). The previous devices like tape drives, card readers / punches,
printers, and paper tape only processed data sequentially. ISAM was a hybrid
access method that allowed data to be processed in key sequence or by key.
ISAM should of meet its death with the introduction of the IBM 370 in the mid
70's and in fact was net replaced / improved by something called VSAM. ISAM's
demise however was slow and lingering even though the product vendor its self
(IBM) officially announced drop of support many many times and then was forced
to extended its life.
When the vendor wanted to kill ISAM it took over 30 years for it to happen (if
its happened yet). The vendor does not want to kill the mainframe ... When
it does, feel free to start your timers ... In this case time to be measured
with a count of rotations of the earth around the sun.
In the late 70's early 80's it was my pleasure to work for Amdahl ... a maker of plug compatible
IBM mainframes. The companies founder Gene Amdahl was the architect of the IBM 360 family of
computers. The IBM 360 had a weird primary design objective ... to make it easy to program in
machine or assembler language. C++ (A and B were not successful) did not exist in those days. The
360 had hardware functions like "Convert To Binary" and "Move Character Long"
that required complex coded subroutines on all other machines. At the time that Amdahl started his
own firm the need for ease of assembler coding was no longer important as there were second and
third generation high level languages. The The computer world design objective had shifted to
speed and cost effectiveness. The 360 instruction set was the worst for speed. Some instructions
like load would take a very small number of cycles and some like MVCL could take hundreds or
thousands. The trick to speed in those days were things like pipelining and RIS. Why did Gene
Amdahl build a IBM mainframe compatible processor in the 70's? He reasoned that no one would
rewrite JCL just to run on a bigger faster more cost effective processor.
Where will the mainframe be in 10 years? We know from the history of ISAM that
it will take 30+ years to die after the vendor announces its demise and the
timer has not started yet.
When I was a grade school student I was told that nuclear energy would make
electricity so inexpensive that it would no longer be metered. I received a
free ticket to ride on the first regularly scheduled public transportation to
the moon. I am now over 35 (by quite a bit) and none of these things have come
to pass.
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