DESCRIPTION OF IBM 360/67 AND CP/CMS SOFTWARE

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-01092A000100100004-5
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 14
• Document Creation Date: December 12, 2016
• Document Release Date: April 8, 2002
• Sequence Number: 4
• Content Type: REQ

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Description of IBM 360/67 and CP/CMS Software
The IBM System 360/67 was specifically designed to overcome the
problems encountered in programming and operating a time-sharing
* application. The following features are considered necessary in an
on-line computing environment:
1. CPU Speed - The 200 ilianosec internal cycle time assures
a fast response to console users.. The necessity of a high-speed
CPU. in this environment is not to handle a few staggered demands
for service, but to insure that when multiple instantaneous user's
demands exist, the apparent terminal response is not degraded.
Most computer systems designs are built around a turnaround
criteria of hours; and job load averages in this spectrum of time
.can be analyzed to determine the best CPU cost vs. time tradeoff.
In a time-sharing system this same system design technique is
invalid. The on-line system which uses only response as a measure
of its acceptability requires a high-powered CPU, a CPU which is
excessive in regard to the computing demands of the on-line users.
Any inefficiency in this type operation suggests that the system also
accommodate another class of user,. the background job. This low
priority work must be available to absorb the excess CPU capability.
2. Dynamic Relocation - This feature on the Model 67 insures
the security of user data and programs which co-exist in the same
real memory. It also provides the control programs with the hardware
necessary to overcome the core fragmentation problem; therefore.,
only programs and data which are actually in use require residence
in high-speed memory.
3. Channel Architecture - The channels in Model 67 are self-
contained; that is, they are not part of the CPU as they are on the
less powerful. models of the System/360. This arrangement has two
advantages--first, a hardware error in the channel does not bring
the system down completely; second, when this architecture is further
extended by the inclusion of a channel controller IBM 2846 in the
system ',onfiguration, the probability 7f interference between the
channel and CPU memory demands is reduced.
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4. Reconfiguration - In the Model 67 system equipped with
a configuration console, the.probability of extended system
outage is considerably reduced. The cperator need only switch
out defective components and gracefully degrade system performance.
The real advantage of any computing system is, of course, its
software. In this respect, the System 360/67 is unique. The CP/67
which is the time-sharing part of the system program has evolved
from an earlier system CP/40 which was operational over two years
ago.
The CMS (Cambridge Monitor System), which is one of the on-line
programming systems available to the terminal user, is the same
system that operated with CP/40 and therefore has benefited through
two years of use.
The specific advantages of the CP/67 come from its creation in
a dynamic sense of many"virtual computers." This technique allows
the terminal user to regard his console as an operator's console,
1052, and he programs as if he is running on a 360 computer by
himself. This organization permits the individual terminal user a
multitude of already existant programs and lowers the cost of converting
to an on-line programming environment.
The CP/67 system has the following attributes:
1. Compatibility - Most significantly by being able to run OS,
it is completely compatible with the rest of the installation.
2. Openended - CP/67 allows execution in a virtual machine any
360 programs which are not timing dependent nor have data driven
I/O.
3. Security - The virtual machines are accessed through a
password scheme and since all memory and I/O references invoke
mapping by hardware and software, the security of the individual's
data is nearly absolute.
4. Maintainability - The system is easily maintained for two
reasons; first, because it is relatively small; second, because it is
very modular and the individual modules have very little dependence
on one another.
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5. Proven System - The system has been over two years in
operational development and has been successful in operation
in a customer site (Lincoln Lab) for over a year where it
cur. rentl 1 supports 30 terminals.
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Questions and Answers on Model 67 and CP
1. What is CP?
A Time-Sharing System for the Model 360/ 67 hardware.
2. What does it do?
This software system, working in conjunction with the hardware,
creates a unique environment called the virtual machine.
3. How does it compare with MFT and MVT?
There is a functional difference between CP and other current
operating systems. In CP, the common user functions usually
called data management are separate from those functions
necessary to perform multi-programming. Under the other
systems, multi-programming and data management are combined
and usually user directed. .
4. Under CP on the Model 67, how many virtual systems can be "sysgenned"
into the system?
This is limited by the amount of space, I/O, and secondary storage
which are available.
5. What is a virtual system?
Virtual system is a simulated 360 environment in which all inter-
user conflicts are resolved through mapping by either software of
hardware, or both.
6. What systems can be operable under CP? (OS, CMS? ? ? )
Any non-timing dependent/360 program-is operable in a virtual
system.
7. What is the limit to. the number of users on line at the same time
under CP?
The limit on the number of users depends on the load conditions
but currently there are 30 on-line users at the Lincoln Laboratory.
Plans call for another control unit and then the number will double.
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8. When are the bounds of each virtual system defined? Can they
be altered at.any time?
The bounds of each virtual system are defined in the user
directory. It can be altered by creating a new directory
before start-up.
9. What device support is available under CP?
A. 2260
B. 2250
C. 2741
D. Disk drives 2314, 2311
E. Drums 2301, 2303
E. Large core storage is being implemented at Washington State.
G. Printers--No restriction as to the number of printers.
H. Card Reader-Punch--no restriction as to number.
10. Can one use RJE's with this system?
Yes, current plans include 1130 support. as an RJE terminal.
11. Would it be practical?
12. Is there much degradation to the system if they are all on at once?
Degradation in a time-sharing paging environment is a function
of the load of the terminals. In a correctly operating system,
degradation should be linear as the load.
13. Can any one virtual system interfere with any other virtual system?
Even deliberately?
14. If data is written on a disk or other I/O device by one virtual systen
can it easily be accessed by another virtual system?
Access to I/O data is only achievable through the directory.
Therefore, users can be prohibited or permitted access to one
another'::; data by altering the directory before start-up.
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.15. Can remote terminals be used with this system?
Yes
16. Can the remote terminals be.on-line with the batch?
17. Is there any chance that one remote terminal may retrieve
data from another area other than the area he is using?
18. Does the remote terminal degrade much from batch performance?
Even with a compute bound job?
Degradation in the time-sharing system is severe for jobs which
misuse core even in a batch system. Jobs which are written
to run well in the batch environment tend to perform well in
the time -sharing environment.
CMS is the Cambridge Monitor System. It is the Operating System
used by the terminal user. It provides on-line capabilities such
as FORTRAN, PL/l, context editing, SNO BOL.
20. How does it compare with OS?-
In comparing CMS with OS, with CMS we have a subset of the OS
data management functions and a subset of the languages available
under OS and no multiprogramming facilities. CMS is comparable
to FMS (Fortran Monitor System) for the IBM 7090.
21. Which types of jobs, I/O or compute bound, run best under the CP
system?
I/O bound jobs tend to run best unde"" the CP system.
22. Why?
Because there is a greater amount of time available for multi-
programming with these type jobs.
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23. Is there a significant increase in performance with faster data
rate I/O (2311 vs. 2314 vs. 2303 vs. large core)?
System performance with :regard to the I/O system depends
heavily on the ratio of core space and CPU demands to I/O
demands.
24. With only 444k bytes of physical core available, how can the
machine act as if it has 1 meg. bytes available?
By the use of a hardware relocation device which maps all
storage references, those pages (i. e. , 4096 bytes) which are
not in core are brought in from secondary storage and the
relocation device is updated.
25. What is paging?
Paging is the .artificial division of a user program's address
space. In the 360/67, this space is divided into 4096 byte
pages. Addresses generated by the CPU pass through and
are acted upon by a hardware relocation device before reaching
the execution store. Those pages which are not in the physical
core store are retrieved from secondary storage devices (drum,
disk). The entries for the relocation device are changed to
reflect the swap from drum.to core.
26. Is only part of the program stored in core at any one time?
The part of the program required for execution is in core.
27. If so, where is the rest of it?
On some secondary storage device (drum or disk).
28. If two small programs are operating under two virtual systems,
might everything remain in core from both systems at the same
time ?
Yes, if the sum of the two active page requirements is less than
or equal to the number of available pages in a physical core.
29. Under CP and the concept of virtual systems, how large can a
program be before it runs out of core?
16 million bytes, i. e., the number of bits in the address field.
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30. If one virtual OS systems fail, does it brifig down.the whole
system?
No
31. If, CP fails, does it bring down the whole system?
Yes
32. Does CP have both input and output spooling?
Yes
33. How can the output from separate jobs bekept separate?
By prefixing the printed output with a user ID.
34. Is there a way to 'direct certain job output stream to a certain
printer ?
This facility is currently being implemented.
35. From the same system input device (i. e. , card reader -punch)
how does the input go to the intended OS virtual system?
By preceding the user input cards with a user ID card.
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ATTACHMENT I
26 4pril 1968
MEMORANDUM FOR: Computer Science Advisor
SUBJECT. : Planning for IBM 360/50 Replacement
1. I would like you to form an ad hoc group within the Office to
STATINTL study the alternatives and recommend a course of action regarding the
replacement of the 360/50 in the Computer Center you know, this
computer
2. In analyzing the alternatives, the following factors should be
considered:
a. The system will be used principally in the time sharing
mode. Background processing for efficient computer utilization
is desirable but not mandatory.
b. I do not believe we can plan to move into a completely
integrated software system including multiprocessing, multipro-
gramming, and time sharing as the standard Operating System in
the Center. Compatibility with the software and hardware used in
the Center is certainly desirable, particularly if main frame con-
nections are feasible for passing tasks back and forth.
c. We should assume that by January 1969 the customer re-
quirements and our experience with time sharing will be such that
a stand alone production time sharing environment will be feasible
and desirable.
d. Movement toward a production environment will make sys-
tem experimentation and extension more difficult than it is now, but
through judicious planning (and perhaps the use of IPRD facilities),
we should be able to continue experimentation at a reasonable pace.
e. Costs must stay within current budget estimates. Supple-
mentary funding could be justified only if major new requirements
were surfaced.
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f. Conversion to the new equipment should be as painless as
possible.
g. We have no firm basis for projecting load other than what
we know-about existing applications and informal requirements.
We should assume that the known requirements will constitute the
minimum load to be expected. .
3. The above factors tend to reduce the number of hardware alter-
natives that must be considered seriously. In my view, the following are
the more obvious ones (in no particular order, with no comment):
a. A 360/50 starting with the configuration identical with the
current one but expanding as needs arise (LCS, AMCS, 2314's,
etc. ).
b. Two stand alone 360/401s, one for Agency sensitive data,
the other for everything else.
c. A 360/67 using a minimal configuration needed for TSMON
(with or without CP67).
d. A 360/65 configured for time sharing.
e. A Spectra 70/46.
4. Software alternatives are perhaps the more difficult to evaluate.
Some random thoughts: We have to assume that the programming talent
that can be applied to time sharing software and related application serv-
ices (in quality and quantity) will always be less than optimal. But I
think the "shoe string" effort thus far can be expanded over the next year
because we have encouraging tangible results. We should concentrate on
building and expanding services peculiar to our installation, perhaps at
the expense of building monitors or spending time making them more
efficient. As the system becomes saturated, our first question should be
whether modest increases. in hardware would keep the system going rather
than to immediately task our available programming manpower to squeeze
more from the exi 3?ting hardware. Only when serious overload is expected
should we. look to improved or new monitors. In this way, I would hope
that we could keep the system going until efficient monitors that meet
our needs become available from the outside, using our people in the
meantime to build more and better application services.
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5. Your findings should be available by 1 June so that a decision
can be made and an order placed with sufficient lead time.
STATINTL
Deputy Director of Computer Services
cc: D/OCS
TIC Members
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ATTACHMENT J
MEMORANDUM FOR THE RECORD
SUBJECT: Trip to RCA on Spectra -70/46
STATINTL
STATINTL ? 1. On 17 June 1968, went t~
STATINTL
New Jersey, to test the Spectra 70/46 and talk to systems personnel.
(See attached for a description of Spectra 70/46 as written by Totaro of
Auerbach and distributed by RCA.)
2. Meinstein, RCA, stated RCA's time sharing objectives as
follows:
a. "To provide concurrent service to a large number of users
at remote points. "
b: "To supply the user with immediate access to a computer
so that it appears to him that he is the only user. "
He gave an overview description of the hardware which is included in the
attachment. He explained that 524K of memory was rejected because of
cost and thus the S-46 was a 262 byte machine. System design programs
are separated into two classes.
Class 1 - that which is brought over, must be loaded in entirety,
must be loaded contiguously, must use private volumes, must never
be paged, and memory is not to be 'relinquished.
Class 2 - Program is created on S-46 with TDOS compilers,
pages are pageable, certain pages are not to be moved, only the
page with an entry point must be loaded to start, may share public
and/or private volumes.
In data management, SAM and BDAM are available on all devices except
RACE. BTAM (Basic Tape Access Method) is available. ISAM is avail-
able on all DASD except on RACE.
All code is re-entrant. Is this because of insufficient memory size?
Is it worthwhile? This was rather unusual since there is a trend to forget
re-entrant code on paging hardware. Cataloging is available by name.
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JCL and TCL (Terminal Control Language) are a single language
which is an .excellent feature. The operator. can designate number of
pages limited to a class 1 program.
3. Performance Tests. In order to demonstrate that the S-46 works,
an unofficial demonstration was given. One typewriter terminal was
activated and then 39 copies of another program were simulated by attach-
ing a S-?45 to the 5-46. Performance and response were impressive.
However, as most time sharing implementers have discovered, a syn-
chronous and perfectly interleaved load is not the same as humans
asynchronously interacting with a system. Whether RCA really has a
better time sharing technique than others could not be determined. If a
machine as low powered and with as small memory as the S-46 can handle
40 users with 1-2 second response time, RCA has a winner. In conclusion,
I am willing to go on record with my personal opinion that RCA is in for a
rude awakening on performance. In my opinion, RCA on the S-46 will not
provide 40-48 users with adequate response time. When load peaks and
especially with complicated queries or. calculations, I b-lieve the
response time will degrade to many seconds, or even minutes and cus-
tomers will be dissatisfied. Unfortunately, RCA's system cannot be
adequately exercised and measured.
4. Device support.
Data Cell. RCA offers its RACE; and even though direct access
is not supported under S-46, they offered to help move SANCA over
to the RACE.
Fast Direct Storage. RCA will not have its own large disk until
1970, but they offered to interface with a 23114.
2250. They can interface through an 1130. They have no com-
parable piece of equipment manufactured by RCA.
5. Language Support. RCA supports FORTRAN and COBOL. The
statement was made that a S-46 could handle jobs as fast as the Mod 65,
even in FORTRAN. OCS is supplying them with the 13 jobs from the
benchmark test so that they can compare their times with a Mod 65.
Several similar statements were very disconcerting and reminded me of
performance cla: ms for the S-70/45 before delivery. However, if what
they are claiming is true (or even partially), OCS should immediately
substitute RCA equipment for all IBM gear. Just to satisfy all.parties
concerned, RCA must complete the comparison testing of the FORTRAN
programs.
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6. Summary. Very interesting. RCA has very impressive tech
nicians. They are making many ambitious claims. If these are really
true, they should be given strong consideration in new time sharing
equipment selection.
STATINTL
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