Editing CDC 6600 (section)

==Operating system and programming==
There was a sore point with the 6600 [[operating system]] support&nbsp;— slipping timelines. The machines originally{{When|date=May 2022}} ran a very simple [[batch processing|job-control]] system known as COS ([[Chippewa Operating System]]), which was quickly "thrown together" based on the earlier [[CDC 3000 series|CDC 3000]] operating system in order to have something running to test the systems for delivery. However the machines were intended to be delivered with a much more powerful system known as SIPROS (for Simultaneous Processing Operating System), which was being developed at the company's System Sciences Division in [[Los Angeles]]. Customers were impressed with SIPROS' feature list, and many had SIPROS written into their delivery contracts.

SIPROS turned out to be a major fiasco. Development timelines continued to slip, costing CDC major amounts of profit in the form of delivery delay penalties. After several months of waiting with the machines ready to be shipped, the project was eventually cancelled. The programmers who had worked on COS had little faith in SIPROS and had continued working on improving COS.

Operating system development then split into two camps. The CDC-sanctioned evolution of COS was undertaken at the [[Sunnyvale, California]] software development laboratory. Many customers eventually took delivery of their systems with this software, then known as [[CDC SCOPE|SCOPE]] (Supervisory Control Of Program Execution). SCOPE version 1 was, essentially, dis-assembled COS; SCOPE version 2 included new device and file system support; SCOPE version 3 included permanent file support, EI/200 remote batch support, and INTERCOM [[time-sharing]] support. SCOPE always had significant reliability and maintainability issues. [[File:CDC 6000 series SCOPE 3.1 building itself.PNG|thumb|CDC 6000 series SCOPE 3.1 building itself while running on Desktop CYBER emulator]]

The underground evolution of COS took place at the [[Arden Hills, Minnesota]] assembly plant.{{When|date=May 2022}} MACE ([Greg] Mansfield And [Dave] Cahlander Executive) was written largely by a single programmer in the off-hours when machines were available. Its feature set was essentially the same as COS and SCOPE 1. It retained the earlier COS file system, but made significant advances in code modularity to improve system reliability and adaptiveness to new storage devices. MACE was never an official product, although many customers were able to wrangle a copy from CDC.

The unofficial MACE software was later chosen over the official SCOPE product as the basis of the next CDC operating system, [[CDC Kronos|Kronos]], named after the [[Chronos|Greek god of time]]. The main marketing reason for its adoption was the development of its TELEX time-sharing feature and its BATCHIO remote batch feature. Kronos continued to use the COS/SCOPE 1 file system with the addition of a permanent file feature.

An attempt to unify the SCOPE and Kronos operating system products produced [[NOS (operating system)|NOS]], (Network Operating System).{{When|date=May 2022}} NOS was intended to be the sole operating system for all CDC machines, a fact CDC promoted heavily. Many SCOPE customers remained software-dependent on the SCOPE architecture, so CDC simply renamed it NOS/BE (Batch Environment), and were able to claim that everyone was thus running NOS. In practice, it was far easier to modify the Kronos code base to add SCOPE features than the reverse.

The assembly plant environment also produced other operating systems which were never intended for customer use.{{When|date=May 2022}} These included the engineering tools SMM for hardware testing, and KALEIDOSCOPE, for software [[smoke testing (software)|smoke testing]]. Another commonly used tool for CDC Field Engineers during testing was MALET (Maintenance Application Language for Equipment Testing), which was used to stress test components and devices after repairs or servicing by engineers. Testing conditions often used hard disk packs and magnetic tapes which were deliberately marked with errors to determine if the errors would be detected by MALET and the engineer.

The names SCOPE and COMPASS were used by CDC for both the [[CDC 6000 series]], including the 6600, and the [[CDC 3000 series]]:
* The name [[COMPASS]] was used by CDC for the [[Assembly language]]s on both families.<ref>{{cite web
|url=http://www.bitsavers.org/pdf/cdc/3x00/24bit/60184200_compassTrng_May67.pdf
|title=COMPASS for 24 bit machines
|access-date=2017-10-15
|archive-url=https://web.archive.org/web/20120910064824/http://www.bitsavers.org/pdf/cdc/3x00/24bit/60184200_compassTrng_May67.pdf
|archive-date=2012-09-10
|url-status=dead
}}</ref><ref>{{cite web
|url=http://www.bitsavers.org/pdf/cdc/3x00/48bit/60052500C_COMPASS_Ref_Dec67.pdf
|title=COMPASS for 48 bit machines}}</ref>
* The name [[CDC SCOPE|SCOPE]] was used for its implementations on the 3000 and 6000 series.<ref name=SCOPE.3000>"CDC delivered an early version of their SCOPE operating system for the 3600" {{cite book
|title=Advances in Nuclear Science and Technology
|url=https://books.google.com/books?isbn=1483215660 |isbn=978-1483215662
|first1=Ernest J. |last1= Henley |first2=Jeffery |last2=Lewins |date=2014| publisher=Elsevier }}</ref>