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x'1D' (29): The Subtasking Monitor and Environment Switch

posted Sep 9, 2019, 2:53 AM by Jeff Ogden   [ updated Sep 9, 2019, 2:56 AM ]

I received the following message from Ralph Sayle the other day. Ralph and I share the same birthday, October 14th.

From: Ralph Austin Sayle
To: Jeff Ogden
Subject: Two items for the mts archives

Greetings Jeff and since our birthdays are a month and a few days away, I won’t mention them.

But recently I found the answer to the grandchildren’s question “what did you do when you worked.”

First off I must declare I had no children and they had no children but I do have a former great nephew whose wife works with information systems at SFU. He is slightly amused at how things used to work... like me.

So two items for the MTS archives: Jeff Berryman’s 1980 paper on “Using the Subtasking Monitor for MTS DSRs” and my very recent “summary” of “What was the Environment Switch”.

Jeff’s paper was his blueskying of what shortly was named Environment Switch. I never read it at the time but did my implementation from his stripped down diagram.

My summary is larger than it needs to be because it backs up to explain the Resource Manager terms, tools, timelines and people. This is documentation that should be elsewhere but isn’t.

Historians say that a history should be written a 100 years after an event. I waited nearly 40 years and if I waited any longer, there’d be neither an audience nor a writer.



The two PDFs included in Ralph's message:

x'1B' (27): MTS-UM Message System CPU Use

posted Sep 9, 2019, 2:06 AM by Jeff Ogden   [ updated Sep 9, 2019, 2:17 AM ]

Gavin Eadie sent the following note at 1:08 am on September 9,, 2019:

    From: Gavin Eadie
        To: Jeff Ogden
Subject: Digging through old floppies, I found this ..


x'1A' (26): MTS Status Lights

posted Jan 10, 2018, 8:23 PM by Jeff Ogden   [ updated Jan 10, 2018, 8:29 PM ]

From: Jon Sell 
Subject: CNTR status lights
Date: January 10, 2018 at 10:18:26 PM EST
To: mts-interest@umich.edu

I’m thinking of putting this on eBay and donating the proceeds to the Bentley Historical Library. I’m afraid it won’t get a lot of attention or a good price without some promotion. Am I delusional or does anyone else think this would be a collectible for well healed Michigan graduates who suffered through late nights at the North Campus Computing Center?

I’m looking for ideas.

How did I get this? Took it out of the dumpster after my office was bulldozed to make room for an on ramp to the Information Superhighway, as they used to call the Internet. 

Why does my brain keep saying Don’t Panic?


Sent from my iPhone

From: David Hetrick 
Subject: Re: CNTR status lights
Date: January 10, 2018 at 11:08:30 PM EST
To: Jeff Ogden 
Cc: mts-interest@umich.edu

Brings back memories (MS CCS 1977), submitting jobs until the green light went off, then punching cards until it came back on.

Alas, I am not well-heeled.

    Dave Hetrick - University of Michigan - retired
    Research Seminar in Quantitative Economics

x'19' (25): Social Software Timeline and Old Memories – Seen on Infocult, the Social Software Timeline

posted Jun 26, 2016, 8:49 PM by Jeff Ogden

From: http://www.group42.ca/social_software_timeline.

Group 42: A site by Dale McGladdery

Social Software Timeline and Old Memories

Submitted by Dale on July 18, 2007 - 11:34am

Seen on Infocult, the Social Software Timeline.

I'd forgotten how much "text only" computing history there is.

Scary, I actually used The Michigan Terminal System. Everyone called it MTS and it was a trivia question answer to know what MTS stood for. I think the only major competing three letter acronym of the day, at least in Canada, was Manitoba Telephone System.

MTS was used for academic computing by Simon Fraser University (SFU) and the University of BC (UBC). I worked at SFU in the early 80's. I don't remember ever using CONFER but a programmer at UBC (Alan Ballard, I think) wrote a program called Forum that took off like wild fire. I hope I'm not mis-remembering but I believe he wrote it over a weekend. The user interface completely blew away any bulletin board software of the day.

x'18' (24): E-mail from Daniel Boulet, 17 March 2016

posted Mar 17, 2016, 10:53 AM by Jeff Ogden   [ updated Mar 17, 2016, 11:28 AM ]

From: Daniel Boulet
Subject: Fixed an error in my Everything2 writeup that you reference on the Michigan Terminal System Archive site
Date: March 17, 2016 at 1:38:23 PM EDT
To: mts-comments@umich.edu

I ran across the Michigan Terminal System Archive site earlier today. Talk about a walk down memory lane! Thanks to everyone involved in creating, building and maintaining the site.

I did the ego thing of looking for references to my last name and found two. One of them on


discusses how I got the full name of UMMPS wrong on my Everything2 writeup at


It turns out that I made the same mistake on a second Everything2 writeup that is referenced on your site's Documents page at https://sites.google.com/site/michiganterminalsystem/documentation ).

I have fixed both Everything2 writeups.



P.S. The Everything2 site looks like it is gradually dying. I don’t have anywhere else right now to put my Everything2 article reminiscing about MTS. I have no idea if this is appropriate from your perspective but you should feel free to copy the contents of http://www.everything2.com/user/dabcanboulet/writeups/Michigan+Terminal+System to your site or somewhere else if you want to preserve it.

A copy of the MTS article from Everything2.com is available here:

A PDF version of the article is available here:

x'17' (23): FORTRAN protest @ UM

posted Dec 14, 2015, 12:32 AM by Jeff Ogden   [ updated Dec 14, 2015, 1:12 AM ]

An online article taken from the Michigan Engineer Alumni Magazine:


Throwback Thursday, mid 80s
October 15, 2015

Chemical engineering professor Brice Carnahan (PhD ’65) introduced computer programming lectures concerning the Michigan Algorithm Decoder (MAD) language beginning in 1960. The lectures proved so popular that they lasted until 1985 – by which time the topic had long since switched to FORTRAN. These computing center employees and student “picketers” (photographed sometime in the early 1980s) believed FORTRAN was old-fashioned, and preferred the more modern Pascal. But the protest was “only semi-serious,” according to Jeff Ogden, a former computing center employee, and Carnahan was good natured about it. “Alas for those protesters, Pascal fell by the wayside, and FORTRAN continued for many years,” says chemical engineering emeritus professor James Wilkes (MSE ChE ’56, PhD ’63).

This throwback is featured in the latest issue of The Michigan Engineer magazine. If you’ve seen it, please let us know what you think.

1 Reply
Carol Kamm
Carol Kamm Used both Fortran and Algol-W early on (i.e. late 70s). Pretty sure I had classes with at least some of these guys - they look really familiar.
Suzanne Botkin McGhee
Suzanne Botkin McGhee This brought back memories of learning both fortran and pascal in college. yikes.
Eli Garza
Eli Garza Yes Carol I did too in the late 70's. Fortran based programs were used in the two firms I worked for into the 2000's! I've never run into others who learned Algol. Never used it in real life however.
Jerome Gilbert
Jerome Gilbert Engineering 102 FORTRAN from freshman year 1975, remember it well!
Aaron Decker
Aaron Decker Fortran was alive and was the focus in our 1990 intro to programming class @ U of M
Connie Skinner-Klunder
Connie Skinner-Klunder I had to take Fortran in 1987 and NEVER used it after
Elizabeth C Hainey
Elizabeth C Hainey Brice was one of my advisors in grad school - great guy!
Greg Brand
Greg Brand I learned Fortran in 2004 for CEE 303
Janice Austin
Janice Austin I had Professor Carnahan for Fortran in 1996 and Professor Wilkes for Fluid Mechanics in 1997.
Lee Burnham
Lee Burnham gotta love geek humor
Jim Buczkowski
Jim Buczkowski Not me! Although I can identify with Fortran!
A Harvey Bell IV
A Harvey Bell IV The text was called the MAD Primer!
Like · Reply · October 15 at 8:28pm


Some background:

On Thu, Jun 18, 2015 at 11:13 AM Randy Milgrom wrote:
Dan -- any help you can provide with these photos would be much appreciated. (If you'd like me to stop asking you these kinds of questions, please just let me know.)

Thanks very much,

Randy Milgrom
Bicentennial Project Editor and Writer
Office of Communications & Marketing
University of Michigan College of Engineering


From: Dan Atkins
Date: Sun, Jun 21, 2015 at 11:08 PM
Subject: Re: help with photo ID
To: Randy Milgrom

Sorry I can't help with these. They are from the computing center IBM mainframe days and I was not involved in that. Here are some old timers from the competing center that might be of help:

Gavin Eadie
Greg Marks 
Randy Frank
Toby Teorey 


From: Randy Milgrom
Subject: Fwd: help with photo ID
Date: June 22, 2015 at 10:14:09 AM EDT
To: gavin, gmarks63, frank, teorey

Hello all,

Please see [above]. Dan Atkins suggested that you might be able to shed some light on some of the photos in the link I've provided. I would appreciate it very much if you might take the time to peruse them and offer any information you might have.

In addition (and even more importantly, actually), I also have provided a pdf of several other photos we are contemplating using for our two-page "throwback" spread in the next issue of Michigan Engineer magazine. I am particularly interested in knowing as much as possible about the photo with the several students (I assume they're students) who are carrying signs concerning the merits and demerits of Fortran and Pascal.

Thank you in advance for any insight you might be able to provide

Randy Milgrom
Bicentennial Project Editor and Writer
Office of Communications & Marketing
University of Michigan College of Engineering


From: Gavin Eadie
Date: June 22, 2015 at 10:52:43 AM EDT
To: Jeff Ogden
Subject: Fwd: help with photo ID

(a) you might be better at recognizing some of this (I see Fred Swartz in the PDF), and
(b) I don’t know what’s behind this, but thought you want to know about it .. Gav


On Jun 22, 2015, at 10:14 AM, Randy Milgrom <rhmilgro@umich.edu> wrote:

I am particularly interested in knowing as much as possible about the photo with the several students (I assume they're students) who are carrying signs concerning the merits and demerits of Fortran and Pascal.


From: Jeff Ogden
Date: June 22, 2015 at 10:46:56 PM EDT
To: Randy Milgrom
Cc: Gavin Eadie
Subject: Re: help with photo ID

I'm going to reply in two or three separate messages. This is the first reply and I'll tell you what I know about the "protest" (page 4 of the Throwback PDF).

As I remember it, the protest was only semi-serious. It was in response to the free lectures on an Introduction to "Fortran programming and MTS" that was being given and which had been given for years at the start of the term by Brice Carnahan, a Professor of Chemical Engineering. I think the the U-M Computing Center may have sponsored the lectures over the years, but I don't think I ever knew the details. Certainly the lectures were open to the entire University and not just to CoE. Brice often collaborated with Jim Wikes, another Chemical Engineering Professor. Brice and Jim collaborated on some of the lectures, but I can't remember if Jim was involved during the protest. Both Brice and Jim are Emeritus, still around, and respond to e-mail.

Here is an announcement for one of the series of lectures given at the start of the Winter Term 1984, but I can't say that it was this series for which the protest occurred. This is from the Computing Center Newsletter, 2 January 1984, page 16:

Here is a paragraph from chapter 12 of Jim's book, A Century of Chemical Engineering at The University of Michigan - A Miscellany of Contributions from Historical Documents, Students, Alumni, Staff, Faculty, and Friends 1898–2002, compiled by James O. Wilkes Arthur F. Thurnau Professor Emeritus, Department of Chemical Engineering, University of Michigan, Ann Arbor, 2002, pages 285-286.

The Carnahan evening computing lectures.
As an outgrowth of the Ford Foundation project, Brice Carnahan presented a famous and
highly popular series of six two-hour evening lectures in the U–M Natural Science Auditorium
on computers and programming, first in “MAD” and later in FORTRAN; one memorable
lecture was given in a Batman costume to compensate for a time conflict
with the premier hour of the Batman television series. These evolving lectures
were attended each term by about 300 students, faculty, staff, and lay persons
who needed a quick, non-credit introduction to computers and programming; the
series began in 1960 and lasted for 25 years, until fall 1984, well into the PC era.
Jim Wilkes also presented several of these lectures in the final years of the series.

Chapter 12 of Jim's book contains lots of information on and photographs of computing at the CoE and at Michigan, so here is a PDF of Chapter 12:

The protesters were pushing the idea that Fortran was an old-fashioned and dying language and that people at U-M should be taught about and move on to using more modern languages such as Pascal. I know Brice came out after the lecture to talk to the "protesters". He was good natured about it and seemed to enjoy it.

I remember the protest, but wasn't a participant. The photograph was taken outside the Natural Science Auditorium on main campus. I know Jim Bodwin (not pictured), another U-M Computing Center staff member, participated. I'm guessing that Jim's wife, Diane Bodwin, another Computing Center staff member, may have participated. I have e-mail addresses for both Jim and Diane, if you would like to check with them.

Gavin is right, the second person in from the left is Fred Swartz. He was a staff member at U-M's academic Computing Center where Gavin and I also worked.  I don't recognize the other folks for certain, but the first person on the left might be Shawn KcKee. Today, Shawn is a Research Scientist in the Physics Department in LS&A, he could have been a student back in the days of the protest. I don't recognize any of the other three folks in the page 4 photo.

Gavin was also correct when he said that the U-M's academic Computing Center was not part of or directly associated with the College of Engineering.  You might take a look at these two URLs for additional information about this:





From: Jeff Ogden
Date: June 22, 2015 at 11:23:49 PM EDT
To: Randy Milgrom
Cc: Gavin Eadie
Subject: Re: help with photo ID

This is the second reply and I'll tell you what I know about the rest of the Throwback PDF images.

The images on pages 1, 2, and 3 look like an old time telephone switchboard.  The U-M's Bentley Historical Library wrote a booklet, A Century of Connectivity at the University of Michigan, Nancy Bartlett, Nancy Deromedi, Alice Goff, Christa Lemelin, Brian Williams, Bentley Historical Library, University of Michigan, December 2007, 40 pages. It covers a lot of U-M's telephone, computing, and networking history. A version of the photo appears on page 17 of the booklet with a note that says:
Walter Donnelly, Wilfred B. Shaw, Ruth W. Gjelsness, eds., The University of Michigan: An Encyclopedic Survey (Ann Arbor: University of Michigan Press,1953), 3: 1228.

The photos on pages 5 and 6 are beginning of term registration at Waterman Gym on Main Campus before the days of CRISP when everything was done by hand or with punch cards.

I don't know anything about the photo on page 7.

The photo on page 8 includes Apple Macs, probably the 512K "fat" Macs. You can see the words "UM Comp Center" in white stenciling on the side of the "floppy" disk drive that is bolted to the side of the Mac. I've no idea where the photo was taken. It looks nicer that the Computing Center's typical public site in those days. It might be in the Michigan Union or League or it could be in a residence hall. It sort of looks like a library. Gavin might know more. He was in charge of the Computing Center's microcomputer support in those days, while I was responsible for the public sites. Deb Masten may know more. Deb took over the responsibility for public sites when I left the University. She is still with U-M ITS.

I don't know anything about the photo on page 9.



From: Jeff Ogden <jco@umich.edu>
Date: June 22, 2015 at 11:44:38 PM EDT
To: Randy Milgrom
Cc: Gavin Eadie
Subject: Re: help with photo ID

Oops, I got the note on the photo from the Bentley library booklet wrong, it is actually:

Telephone operators, Systems History (Display Photos and Documents),
Box 68, Information Technology Division Records, Bentley Historical
Library, University of Michigan.



On Jun 22, 2015, at 10:46 PM, Jeff Ogden  wrote:

Gavin is right, the second person in from the left is Fred Swartz. He was a staff member at U-M's academic Computing Center where Gavin and I also worked.  I don't recognize the other folks for certain, but the first person on the left might be Shawn KcKee. Today, Shawn is a Research Scientist in the Physics Department in LS&A, he could have been a student back in the days of the protest. I don't recognize any of the other three folks in the page 4 photo.


Gavin wrote:

.. I’ll go out on a limb and say the rightmost person is Mark Hersey who programmed IBM PCs for the Computing Center.

.. Even further out on that branch, could the second from right be Dave Martin (white shirt in this pic)?


From: Jeff Ogden
Date: June 23, 2015 at 1:01:30 AM EDT
To: Gavin Eadie
Subject: Re: help with photo ID

I wondered if that was Dave Martin. It might be, but I wasn't certain enough to say for sure or even speculate.



From: Gavin Eadie
Date: June 22, 2015 at 12:13:32 PM EDT
To: Randy Milgrom
Cc: Jeff Ogden
Subject: Re: help with photo ID

I wouldn’t bet they are students!

At least, the “Pascal” person is Fred Swartz who worked for the Computing Center when I arrived here (late ‘70s).  The other faces are more and less familiar, but I can't place their names easily.  There are certainly people who’ll do a better job, however.  Dan’s list of possible sources is good, but not optimal for Computing Center history (and some of your other pictures relate to the CC and not CoE).  I’ve forwarded your email to Jeff Odgen and copied him on this reply.

One place to check for CC history is this site, mostly Jeff’s work: http://archive.michigan-terminal-system.org

I’m curious what you’re doing for the Bicentennial Project for two reasons.  One is that I’m curious in general; the other is that the Computing Center and College of Engineering have been mixed up in previous “historical” material over the last decades.  The two organizations weren't organizationally connected, nor worked in the same areas.

Gavin Eadie

PS: I just noticed Dan wrote “.. old timers from the competing center that might be of help.”
Maybe a Freudian slip .. It did feel sometimes like competition !!


On Tue, Jun 23, 2015 at 12:59 AM, Jeff Ogden wrote:
This is the third and final reply and I'll tell you what I know about the images in Google Docs folder that you sent a link for.

1.jpg is a photo taken on the second floor machine room of the U-M Computing Center Building on North Campus (now the School of Information North). The photo was taken looking to the northwest. We are looking at the remote console for the IBM S/360-67 computer. The computer and its local console are up on the third floor of the building. You can also see an IBM magnetic tape drive, either 7- or 9-track and a fancy IBM paper tape reader/punch with vacuum column feeds to the left of the mag tape drive, something you didn't see very often. Racks of user magnetic tapes are in the background.  The person facing us in the photo is Charles Engle. He is talking to Mike Alexander. Charles and Mike were both senior staff members at the U-M Computing Center. Not sure who that is standing in front of the paper tape reader/punch. This photo appears on page 4 (the copyright page) in the booklet from the Bentley Historical Library with a note that says "IBM 360/67, Box 68, Information Technology Division Records, Bentley Historical Library, University of Michigan."

2.jpg may be the loading dock at the North University Building.

3.jpg was taken on the second floor of the Computing Center building on North Campus looking to the southwest. We are looking at three strings of removable pack disk drives.

4.jpg was taken on the second floor of the Computing Center building on North Campus looking to the northeast. It is looking at the same remote console for the IBM S/360-67, paper tape reader/punch, 7- and 9-track magnetic tape drives, just from a different angle. There is a teddy bear on the top of a cabinet in the center of the photo. The cabinet holds a DEC PDP-8 based Data Concentrator. The story is told here: https://www.eecis.udel.edu/~mills/gallery/gallery7.html (Dave Mills was a staff member at the Computing Center while he was a PhD student in Computer and Communication Sciences (LS&A) at Michigan). I think that the person in the foreground with a mag tape in his hand is John Schaefer, an Operations Manager at the Computing Center. Not sure who the person in the background is.

5.jpg was taken on the third floor of the Computing Center during the installation of the Amdahl 470v/6 computer.

6.jpg was taken at the UNYN public site in the basement of the Michigan Union. We are looking at Apple Macs, probably the "fat" Macs.

7.jpg was taken at the Computing Center in the North University Building on Main Campus. I don't recognize the people in the photo, but they are working with power cables for the IBM S/360-67.

I'm guessing that 12.jpg is an IBM 7090, possibly at the Computing Center in the North University Building on Main Campus or at Willow Run. Don Boettner, Len Harding, or Bruce Arden, all old time Computing Center staff members, could probably say for sure.

I don't know anything about 8.jpg, 9.jpg, 10.jpg, or 11.jpg.

Hope this is helpful. Several of these photos are from the time when I was an undergrad student at Michigan and before I became a staff member at the Computing Center. Some of the folks that have been around longer than I have might be able to recognize more people or confirm some of my guesses. These include Scott Gerstenberger, Mike Alexander, Len Harding, Don Boettner, and Gary Pirkola. Most of these folks are in the U-M directory, but if not, I can provide e-mail addresses.

You'll find short bio sketches for some of the Computing Center staff members mentioned in this message or previous messages here:  http://archive.michigan-terminal-system.org/people.

There are more photos here:  http://archive.michigan-terminal-system.org/images. In particular the photos here http://picasaweb.google.com/103267580193222253134/UMComputingCenter?feat=embedwebsite include many photos of computers and other equipment at the Computing Center.



From: Randy Milgrom
Date: June 23, 2015 at 10:44:55 AM EDT
To: Jeff Ogden
Cc: Gavin Eadie
Subject: Re: help with photo ID


I cannot tell you how much I appreciate this. All the time and effort you put into your responses! I cannot thank you enough.

And thank you, Gavin, for forwarding my request to Jeff. I hope that both of you will be willing to be available for other questions I may have over the course of the next couple of years.

Thanks again,

Randy Milgrom
Bicentennial Project Editor and Writer
Office of Communications & Marketing
University of Michigan College of Engineering

x'16' (22): Michigan Digital Automatic Computer (MIDAC)

posted Dec 23, 2014, 7:56 AM by Jeff Ogden   [ updated Jun 2, 2017, 6:00 AM ]

Michigan Digital Automatic Computer

From the Virtual Museum Histories of Information Technology project at the University of Michigan

In 1951, under collaborative sponsorship from the Wright Air Development Center and the United States Air Force, the Willow Run Research Center of the Engineer­ing Research Institute, University of Michigan began development of the Michigan Digital Automatic Computer (MIDAC) with the intention of producing a machine to assist with “the solution of certain complex military problems.” MIDAC was the sixth such digital automatic computer at a research university, and the first computer of its kind in the Midwest. Using the MIDAC was no simple task—a team of scientists and researchers were required to determine if a problem could be solved using the MIDAC. Perhaps the most strik­ing feature of the MIDAC was its shear size and mechanical components. The MIDAC required 12 tons of refrigeration equipment to cool its 500,000 connections and tubes. Additionally, its main memory storage device was a rotating magnetic “drum,” which could store just 6,000 “words,” or short segments of data. The MIDAC became functional in 1953, and was operated by Willow Run’s Digital Computation Department under the leadership of John Carr III until 1958 when the Air Force removed the equipment.

MIDAC: Automatic Computer

Booklet: Willow Run Research Center, Engineering Research Institute, University of Michigan,
undated, perhaps 1952, 16 pages, PDF  Hathi Trust

A New Research Tool

Michigan Alumnus Volume 60, 1953/1954, pages 76 and 77  Hathi Trust

Video: The story of the UM's high-speed electronic computer "Midac" built under the sponsorship of the U.S. Air Force.


Michigan Report, University of Michigan Television
Original: kine pos, b/w, sound, 00:14:37, 1955
Guest: Professor John Carr, Willow Run Laboratories
Producer - director: Don Hall
Moderator: Dan Ritz (?)
Technical supervisor: Fred Remley
Graphic artist: Thomas Coates

Also see:

x'15' (21): Did MTS require a special version of the S/360-67 to run?

posted Dec 15, 2014, 3:52 AM by Jeff Ogden   [ updated Dec 15, 2014, 4:11 AM ]

Here is the backup e-mail on the topic. The topic came up on the Hercules 390 Yahoo Group e-mail list and later there was a series of private messages and an item posted in the Myths and Misconceptions section of the MTS Archive web site.

The cast of characters:
  • Richard (u4gh) is Richard Chycoski, a former systems programmer at Simon Fraser University (SFU).
  • Dave (G4UGM) is Dave Wade, a former MTS user at Newcastle Polytechnic (part of NUMAC in the UK).
  • Mike Alexander is a former Systems Research Programmer and Research Scientist at the University of Michigan Computing Center, Mike, together with Don Boettner, was chief software architect for the Michigan Terminal System (MTS).
  • Jeff Ogden (me), a former counselor, Systems Research Programmer, Associate Director, and Sr. Associate Director at the University of Michigan Computing Center.
  • Gavin Eadie, a former Systems Research Programmer and Associate Director at the U-M Computing Center.

From: Richard Chycoski
Sent: 13 December 2014 01:28
To: hercules-390@yahoogroups.com
Subject: RE: [hercules-390] System 360 Model 67 Reference Card

The MTS archive at <http://archive.michigan-terminal-system.org/documentation/documents> has a downloadable copy of the 360/67 Reference Card. MTS started on a special version of the 360/67, and University of Newcastle was one of the early MTS sites. The MTS site where I worked (Simon Fraser University, near Vancouver, BC) didn't start running MTS until the later '70s, so we didn't have 360/67 reference cards lying around. :-)

- Richard

On Dec 13, 2014, at 12:52 AM, Dave G4UGM wrote on the Hercules 390 Yahoo group:

Whilst MTS used the 360/67 in a special way it was just a standard 360/67 with DAT and 32-bit addressing. However the 360/67 did start life as a modified 360/65.

There is one feature of MTS that folk’s mistake for a hardware modification, as it is implemented via a Pseudo OP code in assembler.

It is explained in:-


in the section entitled “Branch on Program Interrupt” (BPI), but it DOES NOT require any hardware modification.


Sent: 13 December 2014 09:30
To: hercules-390@yahoogroups.com
Subject: Re: [hercules-390] BPI on modern machines (was System 360 Model 67 Reference Card)


What a great instruction- a NOP without an index register (which is used
as mask for the expected/supported program interrupt).

Would it break anything if this would be implemented on current hardware?

I know it would help address-verification dramatically. Maybe there are other[s.]

From: "Dave G4UGM"
To: hercules-390@yahoogroups.com
Date: Sat, 13 Dec 2014 09:34:26 -0000
Subject: RE: [hercules-390] BPI on modern machines (was System 360 Model 67 Reference Card)

I am not sure about this. I know MTS ran on 370 hardware so the code works
on those "out of the box" as well. I know there were tweaks for 370 mode but
not sure if they were in this area...


From: Mike Alexander
To: hercules-390@yahoogroups.com
Date: Sat, 13 Dec 2014 13:53:50 -0500
Subject: Re: [hercules-390] BPI on modern machines (was System 360 Model 67 Reference Card)

Thanks, I always thought it was one of my better ideas. It was very useful in MTS, not just in the system, but in programs that ran in MTS.

You don’t really need hardware changes for this since it’s extremely easy to implement in the program interrupt handler. Implementing it in either way might break something since it’s possible that some code contains one of those special NOPs for other reasons. This still wouldn’t be an issue unless the immediately preceding instruction got a program interrupt. In 20 years or so of use of this I never heard of a case where it caused problems.


From: "Dave G4UGM"
To: <hercules-390@yahoogroups.com>
Date: Sun, 14 Dec 2014 08:22:49 -0000
Subject: RE: [hercules-390] BPI on modern machines (was System 360 Model 67 Reference Card)

So was it ever implemented in hardware?

From: Mike Alexander
To: hercules-390@yahoogroups.com
Date: Sun, 14 Dec 2014 14:16:26 -0500
Subject: Re: [hercules-390] BPI on modern machines (was System 360 Model 67 Reference Card)

The BPI instruction? Not that I know of. Since there was no significant advantage to having it in hardware we never asked anyone to do it.


On Dec 13, 2014, at 3:54 AM, Dave G4UGM wrote:

Perhaps you could add something to say MTS used a “standard” 360/67. Many folks seem to thing BPI needs a hardware mod…

On Dec 13, 2014, at 5:48 AM, Jeff Ogden wrote:

We can add something.

Where are people expressing their opinion / confusion about BPI and hardware mods?

Is there an article or other description somewhere that is causing the confusion?

Where do you think that we should add something?
On the MTS Archive site? The Myths and Misconceptions page?
On Wikipedia? There is a description of BPI in the MTS System Architecture article.
Somewhere else?


On Dec 13, 2014, at 9:51 AM, Dave G4UGM wrote:

They generally say “MTS needed a hardware mod” or “MTS ran on special hardware”, and when pressed they say “something to do with interrupt processing”.
Got one yesterday on the Hercules 390 group:-
“The MTS archive at <http://archive.michigan-terminal-system.org/documentation/documents> has a downloadable copy of the 360/67 Reference Card. MTS started on a special version of the 360/67, and University of Newcastle was one of the early MTS sites. The MTS site where I worked (Simon Fraser University, near Vancouver, BC) didn't start running MTS until the later '70s, so we didn't have 360/67 reference cards lying around. :-)”
So I am not sure if it’s that’s a typo, or they mean a special version of the 360/65, but the same thing cropped up in 2010, from Rob Tatum who is usually a pretty competent guy
From: rhtatum
To: hercules-390@yahoogroups.com
Sent: Tue, October 19, 2010 10:33:40 PM
Subject: Re: [hercules-390] Current status of MTS ?
No, MTS probably won't run under Hercules - I looked up MTS using a google  search, and it seems that there was an additional operation code that the folks that created MTS either did themselves or had IBM implement for switching  between pieces of MTS, user programs, etc. Someone would have to write the simulation code for that op-code for MTS to run under Hercules-390.
Is two enough to be “common”?
Dave Wade

On Dec 13, 2014, at 10:47 AM, Jeff Ogden wrote:

That should be enough to get started. Thanks.


On Dec 13, 2014, at 12:25 PM, Jeff Ogden wrote:


The S/360-67 at Michigan had an RPQ or perhaps several RPQs.  Were they required to run MTS or just performance enhancements?  At onetime I think the RPQ was described in MTS Volume 5, but the PDF that I have is a newer version which doesn't include that description. Was Search List (SLT) part of the RPQ? I know that UMMPS emulated the SLT instruction, but I'm not sure when that was added? And I know that UMMPS stopped using STL at some point (probably when S/370 support was added).

I added a new item to the Myths and Misconceptions section of the MTS Archive Web site about this. Could you take a look and see if I got it right?



On Dec 13, 2014, at 1:37 PM, Mike Alexander wrote:

I saw that message on the Hercules list and even had a reply typed but decided not to send it.  I guess I should have sent it.

There were a couple of RPQs on Michigan’s first 67, but none were required for MTS since other 67s that ran MTS didn’t have them. I’m not even sure our later duplex 67 had them.  One of them was the SLT instruction, but that was never used much and was never required.  All uses of it were under conditional assembly and were optional.  The emulation code was added later when we got machines that didn’t have the RPQ so that any user code that used SLT would still work.  The system never used the emulation code and I doubt if any user code did.  I had a counter on the emulation and never saw it non-zero except when I was testing it.  I can’t recall offhand what the other RPQs were, or even for sure if there were any.  I think that some things started out as RPQs, but became part of the standard machine.

Your new item in M&M looks fine.  You could add something to it about SLT.


On Dec 13, 2014, at 4:20 PM, Jeff Ogden wrote:

OK, thanks.  I think there might have been an RPQ for extended floating-point, but I am always confused about what was done in hardware and what was emulated in UMMPS.

I wouldn't feel too bad about not sending your note. That was a few years ago now (4) and the original comment started out that MTS probably wouldn't run under Hercules.  I think subsequent events have made it quite clear that MTS runs just fine under Hercules.


On Dec 13, 2014, at 5:07 PM, Mike Alexander wrote:

I think that's right that there were floating point related RPQs. There might have been others too.

The message I almost replied to was from yesterday.  It doesn't matter that I didn't reply since "Dave G4UGM" replied with the same comment I was going to make.


On Dec 15, 2014, at 4:03 AM, Jeff Ogden wrote:

I found this in my e-mail archive:

On Aug 2, 2010, at 6:22 PM, among other things Mike Alexander wrote:

Michigan asked for a few things beyond just address translation hardware, including extended precision floating point.  There was concern that the base 16 floating point (which had never been used before) would have problems which extended precision might address. These fears turned out to be true (Len will certainly remember the guard digit fight).  The other features IBM put in for Michigan were the search list and swap register instructions.  When the 370 came out it also had 128 bit floating point, but not quite the same as on the 67.

On Dec 13, 2014, at 4:44 PM, Jeff Ogden wrote:




On Dec 13, 2014, at 4:59 PM, Mike Alexander wrote:

That looks fine.


On Dec 13, 2014, at 5:41 PM, Dave G4UGM wrote:

I think that’s fine Jeff, Thanks very much

From: Richard Chycoski
Sent: 14 December 2014 01:45
To: dave.g4ugm
Subject: Re: System 360 Model 67 Reference Card
Hi, Dave: I've read this in a number of sources, including <https://www.eecs.umich.edu/cse/publications/Publications/CSE_Booklet.pdf>:

Ultimately, IBM’s Model 360/67 was installed at
NUBS in January of 1967. Close cooperation between IBM people
and the Computing Center staff produced modifications of this
design, which became then the IBM 360/67M, the “M” standing
for “Michigan.” The two Computing Center people who were the
primary developers of all the details of MTS were Mike Alexander
and Don Boettner. One measure of their success is the fact that
within a year of the installation of this first IBM360/67M, IBM had
orders for forty more.

This is also how I heard it described by the MTS old-timers (now we're all old :-), including John Hogg (UBC) and Charlie Benet (UM/UQV/SFU).

So that would make it true that UM got 'vanilla' 360/67s, but were later modified and that version sold to others who wanted these added features?

- Richard

From: "Dave G4UGM"
Subject: RE: System 360 Model 67 Reference Card
Date: December 14, 2014 3:43:57 AM EST
To: "'Richard Chycoski'"
Cc: "Jeff Ogden"

Ok so if you look at the references in the end of the booklet, you will see it refers to this:-
“Susan Topol, “A History of MTS--30 Years of Computing Service,” published in the University of Michigan Information Technology Digest, May 13, 1996 Vol. 5, No. 5).”
You will find that article reproduced in its entirety here:-
and its clearly been copied wrongly as that says they got a 65M (a model 65 with DAT) which became the 67….

On Dec 14, 2014, at 6:24 AM, Jeff Ogden wrote:

The Suzan Topol article that Dave mentioned in his reply is a good source for this.

I'm sure that UM got a "standard" S/360-67 in December 1966 / January 1967. It may have had some additional RPQs on it, but they were not related to the virtual memory features of the Model 67 and were not required to run MTS. 

At Dave's urging I added a new item about this to the Myths and Misconceptions section of the MTS Archive web site. Mike Alexander has been following this discussion (he is a member of the mts-comments@umich.edu e-mail group as well as the Hercules 390 e-mail group on Yahoo). Mike looked over the new Myths and Misconceptions item and said it looked fine.

There is in fact some uncertainty about what the actual designation of the one-off version of the Model 65 was before it became a standard product from IBM. It may have been the model 65M as stated in the Susan Topol article, but it may have been the Model 66 or 66M or perhaps a mix of all three at different times. But the uncertainty is about the model designation of the preliminary system and not about what Michigan finally received in December 1966 / January 1967.

There are a number of other sources for this and related topics:

On Dec 14, 2014, at 11:24 AM, Richard Chycoski wrote:

Thanks, Jeff!

Given the muddiness of the remembrances, it's not too surprising that several different versions of the story got propagated through the community - sometimes even into print, where it became 'gospel' :-).

- Richard

On Dec 14, 2014, at 11:29 AM, Gavin Eadie wrote:

History is written by the winners?

On Dec 14, 2014, at 11:44 AM, Richard Chycoski wrote:

Or by the ones with the largest publishing budget - there's even research to suggest that some sections of the Bible in its current form came from copies-of-copies-of-copies of errant manuscripts, because so many copies of the flawed document got propagated, drowning out the earlier (and presumed to be more correct) copies that were later found. Repeat some untruth often enough and it can get to be believed by everyone - too many tyrants have made terrible use of this.

As I've gotten older, I've found how 'fluid' memory is - having memories of things that I saw as a kid, then looking at pictures from the actual time/event. Makes the whole idea of an 'eye witness' quite suspect!

- Richard

x'14' (20): Early designation for the S/360-67: 64 vs. 65M, 66, 66M, and 67M

posted Dec 14, 2014, 11:34 PM by Jeff Ogden   [ updated Dec 15, 2014, 1:58 AM ]

Before the IBM System/360 Model 67 became an officially supported product it was known by several different designations, but after the passage of over 48 years, people's memories differ about exactly what those early designations were.

From the IBM System/360 Model 67 article in the English version of Wikipedia:
  • After a year of negotiations and design studies, IBM agreed to make a one-of-a-kind version of its S/360-65 mainframe computer for the University of Michigan. The S/360-65M would include dynamic address translation (DAT) features that would support virtual memory and allow support for time-sharing.
  • As other organizations heard about the project they were intrigued by the time-sharing idea and expressed interest in ordering the modified IBM S/360 series machines. With this demonstrated interest IBM changed the computer's model number to S/360-67 and made it a supported product.
  • IBM announced the S/360-67 in its August 16, 1965 "blue letters" (a standard mechanism used by IBM to make product announcements).
  • The first S/360-67 was shipped in May 1966. The S/360-67 was withdrawn on March 15, 1977.
From the Talk page for the IBM System/360 Model 67 in the English version of Wikipedia:

Early designation

There's something wrong here in the early history. The first-announced 360s with virtual memory were designated Model 64 and Model 66, virtual-memory versions of the Model 60 and Model 62. Only a few weeks later, IBM withdrew the 60 completely and replaced the 62 and 70 with the higher-spec'ed 65 and 75; at the same time, the 64 was dropped and the 66 replaced by the 67. This is inconsistent with the story that the 67 was first introduced as a "65M" modification to the 65. It is possible, of course, that "65M" was an early designation for what was announced as the 64 or 66. —Preceding unsigned comment added by John W. Kennedy (talkcontribs) 16:48, 12 October 2010 (UTC)

I think the wrongness is the belief that there were models 64 and 66 with virtual memory. I have seen no authoritative evidence for the announcement of models 64 or 66, and no reference to them having virtual memory. The best list of System/360 models I have seen is this one: IBM System/360 Dates and characteristics which does not mention the models 64 or 66 at all. John Sauter (talk) 04:05, 13 October 2010 (UTC)
There is a question if the early designation for the "one off" system for the University of Michigan was 65M, 66, or 66M. See these references:
Jeff Ogden (talk) 22:12, 13 October 2010 (UTC)
The model 66 is mentioned in footnote 21 on page 8 of http://www.princeton.edu/~melinda/25paper.pdf :
“Lincoln [Labs] had a role in the design of the time-sharing machine. I have a copy of IBM’s response to Lincoln’s Request for Quotation, which specified a Model 66. This machine was later to become the 360/67, but I don’t know why the model number changed. A group of six sites (Lincoln Lab, University of Michigan, Carnegie University, Bell Labs, General Motors, and Union Carbide, I believe) had a non-disclosure agreement for the development of the 360/66. This group was called the ‘Inner Six’. At one meeting in Yorktown Heights, we met with IBM people to discuss relocation hardware. We discussed whether an address should be 31 or 32 bits. We eventually voted and recommended 31 bits. We also discussed the design of the relocation register and had some heated discussions with the IBM team. The Inner Six met with IBM representatives behind closed doors at a SHARE meeting. We six sites discussed various features of TSS and made recommendations to IBM. This was the beginning of the SHARE TSS Project.” (J.M. Winett, private communication, 1990.)
Jeff Ogden (talk) 22:31, 13 October 2010 (UTC)
I just looked at a copy of IBM's 360 and Early 370 Systems by Pugh, et. al. and didn't see anything about a Model 64 or 66 listed in "Appendix A: System Introduction Dates 1964-1977" or "Appendix B: Computer Improvements 1953-19679" or in the index. Models 60 and 62 are listed as announced, but never shipped. And of course Models 65 and 67 are listed. Jeff Ogden (talk) 11:56, 17 October 2010 (UTC)
User Chatul found this record of IBM's announcement of the models 64 and 66: DIGITAL COMPUTER hpefthnuitr-: Digital Computer Newsletter, Office of Naval Research, Mathematical Sciences Division, July 1965--pages 5-6: IBM System/360 time-sharing computers. Apparently, the announcement was never “official” because it does not appear in the official history. I speculate that it was written just before the April 22, 1965, substitution of the model 65 for models 60 and 62, and so was withdrawn until August 16, 1965, when the model 67 was announced instead. John Sauter (talk) 12:31, 17 October 2010 (UTC)
I added a mention of models 64 and 66 using words taken more or less directly from the main S/360 article. I left the mention of the one-off model 65M as it was. Jeff Ogden (talk) 02:30, 22 October 2010 (UTC)

From "A Faster Cratchit - The History of Computing at Michigan", U-M Research News, January 1976, Vol. XXVII, No. 1, page 14:

IBM had at first apparently not planned to include the machine selected by the Computing Center in its line of marketable computers. This computer, labeled the System/360 Model 66M (the M in 66M standing for Michigan), was to be one of a kind built to University of Michigan specifications. Fortunately, the tide of interest in equipment that would allow for efficient time-sharing was on the rise. IBM quickly found that the computer proposed to the University of Michigan in accordance with U-M specifications was attractive to other buyers too. Within months the hardware innovations that were unique to the 360/66M were to become standard features in the newly announced System/360 Model 67 computer.

From Atsushi Akera's 2006 Oral History Interview with Bernie Galler, pages 61-66:

AKERA: So it’s possible that the initial conversations took place a little more in the abstract as opposed to in the context of the 360 series. But eventually you knew that it would be, in fact, the 360 model, 66M.

GALLER: Yes, that’s right. We never really knew whether “M” was “Modified” or “Michigan.” [chuckles]

From Computing at the University of Michigan: The Early Years through the 1960s, Norman R. Scott, Computer Science and Engineering, UM College of Engineering, 2008:

Ultimately, IBM’s Model 360/67 was installed at NUBS in January of 1967. Close cooperation between IBM people and the Computing Center staff produced modifications of this design, which became then the IBM 360/67M, the “M” standing for “Michigan.” The two Computing Center people who were the primary developers of all the details of MTS were Mike Alexander and Don Boettner. One measure of their success is the fact that within a year of the installation of this first IBM360/67M, IBM had orders for forty more.

The use of the designation 67M in the above brochure is incorrect. Here is an e-mail exchange with Mike Alexander fromm 2011 that talks about this:

--On January 12, 2011 10:02:46 PM -0500 Jeff Ogden wrote:

p. 12: "Close cooperation between IBM people
and the Computing Center staff produced modifications of this
design, which became then the IBM 360/67M, the “M” standing
for “Michigan.”"

There is a good deal of confusion about the designation used for the
modified S/360-65 with virtual memory support, but I don't think it
was ever a S/360-67M. It may have been a S/360-65M, or S/360-66, or
S/360-66M. When the machine was made "official" by IBM the
designation S/360-67 replaced all of the older one-off designations.

--On January 12, 2011 11:39:07 PM EST Mike Alexander replied:

Right, there was no such thing as 360-67M.

An e-mail exchange between Mike Alexander, Bruce Arden, Scott Gerstenberger, and Jeff Ogden (me) in 2010:

--On June 22, 2010 12:57:02 AM -0400 Jeff Ogden wrote:

Take a look at this section in the Wikipedia article on the IBM 360/67:


The S/360-67 design included a radical new component for
implementing virtual memory, referred to as the "Blaauw Box" after
its designer Gerry Blaauw. This device was originally designed
during the main S/360 project, but had been excluded from the S/360
design; it was revived for IBM's failed proposal to Project MAC, for
a customized S/360, and finally came to fruition in the S/360-67.
The "Blaauw Box" used a somewhat different approach from that
implemented later in the S/370 series in the "DAT box".

From what you two [Scott Gerstenberger and Mike Alexander] were telling me the other evening, I think this is wrong and should probably be corrected.


--On June 22, 2010, at 1:31 AM, Mike Alexander wrote:

This is almost completely wrong.  Bruce clearly knows a lot more about this than I do, since he was a major player in it and this all happened just as I joined the Computing Center in 1965, and I've CCed him so he can correct my mistakes.  However here's what I think happened.

There were several universities and research centers (UM, MIT, GM Research, NASA Lewis (?), and others?) who were interested in getting a machine for time sharing.  They proposed an address translation system along the lines described in the paper "Program and Addressing Structure in a Time-Sharing Environment" by Arden, Galler, O'Brien, and Westervelt.  This described a two level address translation architecture much like what is still used today.  IBM didn't go for this idea and instead proposed the Blaauw Box which implemented a single level address translation.  They totally missed the idea of using the two level translation to control sharing of memory among processes.

IBM went back and forth with the consortium and things were getting nowhere.  On the other hand GE was happy to implement something like what the consortium wanted.  Eventually MIT gave up and ordered a GE machine (which is why Multics was written for GE architecture instead of IBM).  UM was very close to following their lead.  At that time the university/research market was still important to IBM and they were so worried about losing it all to GE that the agreed to implement the architecture the consortium wanted.  The result was the 360/66M (or maybe /65M), a special order machine for the remaining members of the consortium.  After IBM discovered that there was wider demand for this machine, they renumbered it as the 360/67 and made it part of the product line.

The DAT box on the 360/67 did not implement the Blaauw box.  It implemented the architecture described in the paper mentioned above.

Someone should fix the Wikipedia article, although I suspect we'll get some pushback from folks who want to rewrite history.  It would be best to have proper documentation to back up what we say.  I imagine there are documents in the Bentley that cover this period in the Computing Center history.


--On June 23, 2010, at 12:34 PM, Bruce Arden wrote:


The following is a part of my memoirs regarding the Model 67. I don't remember any external Consortium but there were several universities and corporations (e.g. GM) interested in dynamic multiprogramming on a mainframe however. A high level UM committee (I don't remember the members) did authorize the exploration of possibilities.

Regarding the Blaauw Box, I don't have the details here in Maine and probably not in Ann Arbor either. Bentley may have them in Bernie's contribution to their collection. However, I think you are right, Mike. The B-Box was a scheme for the operating system to monitor the setting of base registers with programs assigned to contiguous blocks of virtual memory. This would have some similarities to VMS with the same kind of program transition overhead.


In 1964 The University of Michigan formed a widely representative ad hoc committee to propose means to satisfy the exploding demand for computational service in science and engineering. They recommended that strategies to exploit the multiprogramming use of large mainframe computers, the only way to provide high speed computing at that time, be explored as soon as possible. The introduction of phone-connected terminals as input/output devices, in conjunction with a large multiprogramming capability, would make interactive check-out, or debugging, of new programs possible. University teaching and research activities mean that a large number of new programs are always under development. The interest in facilitating interactive computing existed in many universities at that time.

Michigan had a small head start in developing the related, complex operating systems for academic use. Also in 1964, a mid-size System 360 (model 50) was acquired  by the Computing Center, and, by the subsequent enhancement of a primitive operating system from Lincoln Laboratory, a limited, interactive multiprogramming capability was created. A small, talented group of programmers, led by Michael Alexander, were the architects of this system. This was the beginning of a long sequence of improvements ultimately designated UMMPS (UM MultiProgramming System). The dominant component, to manage interactive programs, developed under the title MTS (Michigan Terminal System).

About the same time a few Computing Center staff members prepared requests for proposals from three mainframe manufacturers - IBM, GE, and Burroughs. These requests, sent in December 1964, described how these companies could retrofit their machines to include another level of address indirection.  GE, then responding to a similar request from MIT, was interested, but the other two were hesitant about such an undertaking. They were unconvinced about the market for such a complex augmentation. IBM’s initial disinterest was discouraging because the System 360 base registers could easily be increased from 24 bits to a full word of 32 bits, and they had experience in the implementation of indirect addressing by base registers. Increasing the address size would greatly expand the virtual address space. (232 = 4,294,967,296)

GE responded to our proposal in March 1965 with a high level description of what had been planned in their collaboration with MIT and Bell Labs. Shortly after our proposal was sent to GE, Michigan was invited to join that collaboration. Our response to the invitation was not enthusiastic. MIT and Bell Labs had written the specifications for the modifications of the GE model 635, an older design with eighteen bit absolute addresses much like the IBM 709. Michigan would be a latecomer to the collaboration without much input to the already existing specifications. Besides, we still believed that the newer IBM System 360 was more amenable to modification. Nonetheless, we were willing to consider joining the GE consortium if there were no other alternative. It was not surprising that IBM was concerned by the loss of MIT and Bell Labs as influential customers, and the prospect of also losing Michigan persuaded them to reconsider our proposal.

The three principle designers of the System 360, Amdahl, Brooks and Blaauw, initially thought that additional indirect addressing was unnecessary clutter on their relatively new design. They generated a counterproposal, nicknamed the Blaauw box, which localized the additional circuitry required but greatly restricted the desired dynamic relocation capability. This proposal was rejected and shortly thereafter IBM agreed in principle to the System 360 augmentation we had suggested. There was still a lack of corporate enthusiasm, however. Apparently IBM believed that the size of the market for such a specialized machine was about one. The augmentation of the System 360 model 65 for Michigan was to be called 65M or alternatively 66. IBM would do no system programming for this unique model, which would not be generally available on the market. But almost immediately requests for this machine began to arrive at IBM from other universities without the system programming experience of Michigan. IBM decided to support the Model 65M for a wider market and it was renamed the Model 67.

The Computing Center began immediately to adapt the prototypical multiprogramming system MTS to the forthcoming Model 67 with its large virtual memory and system-controlled address indirection. IBM simultaneously embarked on a major programming effort to produce TSS (Time Sharing System) in about a year. If this could be done Michigan need not duplicate the effort, and so we collaborated with IBM on TSS design and implementation. There followed almost two years of trips, conferences and study papers. We began to have some reservations about the possibility of completing this huge, complex software project in a timely manner. The specter of having the model 67 delivered without working system programs convinced us to continue some back-up efforts. The UMMPS implementers at Michigan continued with their efforts to incorporate the dynamic relocation capability of the forthcoming Model 67 in their multiprogramming system.

As it turned out, TSS was an enormous undertaking that was not close to completion in its scheduled time, even though IBM assigned hundreds of programmers to the task. It seems that there is an inherent sequentiality in the creation of any complex structure having many interacting parts. The old truism, “Nine pregnant women cannot produce a baby in one month.” seemed to apply.

In January 1967 a single processor Model 67 was delivered. UMMPS and the embedded MTS were rapidly adapted for this larger computer.  But the difficult incorporation of the virtual memory features (dynamic address translation via indirect addressing) was implemented on a testbed basis only until November  1967, when the Model 67 and its controlling programs became fully operational. The productivity improvement was dramatic. Before the new hardware, about five interactive programs could be simultaneously executed. Afterwards fifty could be accommodated with one or more batch programs at the same time. The mix was controlled to keep the processor and the  input/output channels as busy as possible. About nine months later a dual Processor Model 67 was installed, more than doubling the throughput. At that point the controlling programs managed both multiprogramming and multiprocessing, too much for one acronym. Participating in such unbridled innovation was a heady experience, though exhausting. There was still room for individual creativity, unlike building large, complex physical systems such as jet engines.

--On August 2, 2010, at 1:54 PM, Scott Gerstenberger wrote:


My recollection of the model number stories is that originally the 67 was
called a 66M and subsequently (before delivery) changed to a 67 when
IBM realized that other customers besides Michigan, albeit a small number,
were interested in ordering one.


--On August 2, 2010, at 6:22 PM, Mike Alexander wrote:

There was a lot of back and forth about the exact features to be included on the machine for Michigan.  During this process various model numbers were used, sometimes more as internal code names than serious proposals.  I definitely remember a 65M and I think 66.  I don't recall a 64 (or 60 or 62, for that matter).  Perhaps some of these were Blaauw box machines.  I agree with Scott that IBM settled on a more "official" designation (67 instead of 65M) when it appeared that this might not be a one-off for Michigan.

--On August 3, 2010, at 11:37 PM, Scott Gerstenberger wrote:

My recollection is that the original model number was 66M
(not 65M) and that was changed to 67 even before the machine
was delivered to "Ann Harbor, Michigan." But I have no proof.


[Ann Harbor is not a typo or at least not a typo by Scott. -Jeff]

8.1: Some information about LLMPS

posted Oct 19, 2014, 7:47 PM by Jeff Ogden   [ updated Oct 19, 2014, 7:48 PM ]

On Oct 19, 2014, at 9:36 PM, Jeff Ogden wrote:

I've been reading the Computer History Museum's 2009 Oral History Interview of Frank Belvin (http://archive.computerhistory.org/resources/access/text/2013/03/102702246-05-01-acc.pdf). Frank worked at MIT's Lincoln Laboratory and was responsible for the development of LLMPS. He is co-author together with Joel M. Winett of Lincoln Laboratory Multi-Programming Supervisor, Lincoln Manual 78 (ESD-TR-67-14). He went on to co-found IDC [Interactive Data Corporation].

Some background on the development of LLMPS from page 11:

My first task (we had gotten a small model System/360) was working with another fellow, Joel Winett, to develop a multi-programming system that we'd use on the small model 360 to replace all the 1401s that were in the batch shop. It was a typical batch shop, you come in with card decks, they get copied to tape, the tapes go over to the mainframe, you run the job, the mainframe produces output, either cards or on a tape, and then you take the tape back to the 1401 and do printout. We had three 1401s supporting this one 7094, and it was Jack's idea that we should cut our teeth on learning the 360 and do something useful by replacing all those 1401s; so Joel and I wrote a multi-programming operating system with the help of several people in our group who wrote various applications. We ended up replacing the 1401s and I remember a smooth running system.

I came across this on page 14:

And in fact, this little multiprogramming supervisor I mentioned that Joel and I wrote, we contributed that to the SHARE library, and it apparently got heavy use, not only within IBM, but also the University of Michigan picked it up, and it was a little, tiny inside part of the University of Michigan Multi Programming System (UMMPS), which then became the Michigan Terminal System. So we were heavily involved. I had Mike Alexander come out and visit us. We were very open. But that was before we became our own separate commercial company. I think competitiveness at the university and laboratory level is very cooperative, whereas competitiveness outside is your bread and butter, and so you think more carefully about it.

And here is another interesting statement from page 31 (the last page of the interview):

The most fun I've had other than writing LLMPS [Lincoln Laboratory Multi Programming Supervisor]] at Lincoln Laboratory, were the first years [at IDC], even including going through the layoff process, which was a very painful one.


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