Remembering Grace Hopper’s 1974 Visit to Campus


Grace Hopper Visits University of Missouri-Rolla in 1974.

Alumni Memories from Bob Gaebler

Editor’s Note:  Grace Hopper (December 9, 1906 – January 1, 1992) was an American computer scientist and United States Navy rear admiral. She was one of the first programmers of the Harvard Mark I computer in 1944, and she invented the first compiler for a computer programming language. Hopper helped promote the idea of machine-independent programming languages which led to the development of COBOL. She is also credited with popularizing the term “debugging” for fixing computer glitches (in one instance, removing a moth from a computer).  Grace Hopper visited Rolla in 1974 and Alumus, Bob Gaebler, shares his memory of that event.

I attended Grace Hopper’s lecture in the evening. It was not only very charming, but it was informative and inspiring to the point that I still apply some of the insights and lessons she transmitted in that talk.
As for the charming part, she presented her now famous object lesson in which she learned what a nanosecond was – holding up a piece of wire about a foot long, and relating how, early in her career, an engineer explained to her that light travels that distance in the space of a nanosecond, cutting a piece of wire to length so that she could better visualize it. She then related how, when that engineer later mentioned a microsecond, she asked for help in visualizing THAT small time interval. The engineer cut for her a visual aid for that unit of time as well – at this point Grace held up a huge coil of wire about 100 yards long, to universal laughter from the audience. At the end of her evening talk, she passed out free samples of a nanosecond, to any who were interested, as souvenirs of her visit.

Bob Gaebler
B.S. Computer Science, 1977
Marion, IA

DataTerminals – Predecessors of Personal Computers, Part 2 of 2: HP 2647A


Brochure Photo of the HP 2647A Intelligent Graphics Terminal

Alumni Memories from Pam (Thebeau) Leitterman

The top of the line end-user product for the 264X series was the 2647A Intelligent Graphics Terminal.  It made its debut in May 1978 and listed for $8300. It came with a BASIC interpreter, a Multiplot program for creating line, bar, and pie charts, and an HP Slide program for making text-based overhead transparencies using an HP plotter.   Incredibly slick technology for its day, but for those of us now accustomed to projecting powerpoint slides from a laptop, it’s hard to imagine the number of hours and manual attention it used to take to create a 30-page slide deck when you had to align each single transparency on a plotter, start the 4- or 8-pen plotting action, remove the plotted transparency, and then wait for it to fully dry before inserting it into a 3-hole sleeve.   I’m sure I plotted hundreds of slides in my early years at HP.

Here’s a diagram of the input screen for HP Slide followed by a sample of the plotted output from that screen. Notice on the input screen, there was a column labeled “Pen#.” This was the function that allowed text to be in different colors.   Though you could arrange the plotter pens in any order, it was typical to put the black pen in the #1 spot, the red in the #2 spot, the blue in the #3 spot, and the green in the #4 spot. In the example shown below, only pen #1 is used.


HP Slide – Sample Input


HP Slide – Sample Output

More information about the HP2647A Intelligent Graphics Terminal can be found at, a website with links to over 32,000 documents for over 500 companies / organizations. Specific HP2647A documents include:

Related Post:  Data Terminals — Predecessors to Personal Computers,  Part 1 of 2:  HP 2640/44/45

Pam Leitterman
BS Applied Mathematics, 1975
Co-chair CS Golden Jubilee Steering Committee
President, Academy of Computer Science

DataTerminals – Predecessors of Personal Computers, Part 1 of 2: HP 2640/44/45


Pam Leitterman at her desk in HP’s Data Terminals Division, Bldg 43U, in 1979. The new Apple campus is being constructed on the former HP site on Homestead Road in Cupertino, CA where Bldg 43 and other HP buildings were located.

Alumni Memories from Pam  (Thebeau) Leitterman

In July 1979, I embarked on an almost 28-year career with Hewlett-Packard. In my first job, I was a technical marketing engineer for HP’s Data Terminals Division (DTD).   One of my primary responsibilities was to train HP Systems Engineers (SEs) on DTD products. HP was booming then and hiring systems engineers at an incredible rate.   For several years we conducted new hire SE training on our products almost every other week, 20+ SEs at a time.

I supported and delivered training on the 264X terminals. They all featured an 8080 (8-bit) microprocessor and a 15-slot backplane that allowed them to be configured and sold as a series of products with varying degrees of capability. For training purposes, the modularity enabled us to swap out PC boards and key caps to provide hands-on experience with the full product line over a period of several days. Initially, we weren’t aware we might be causing problems for the products due to electrostatic discharge (ESD) that could occur from swapping boards in and out with our bare hands. Later, we learned to wear protective gloves and store our training circuit boards in anti-ESD packaging.

HP’s data terminals were primarily used as consoles and data entry devices for computers. However, the terminals also had enough display memory and intelligence that they could be used as standalone word processing devices. In DTD, we often used them this way to create memos and short documents that we printed to an attached daisy wheel printer, saving our data on the mini cartridge tape drives that were available on most of the product line. Each data cartridge could store a whopping 110,000 bytes of information!

The 2640A, the first of the 264X terminals from HP was introduced in 1974. It displayed 25 lines of text (80 columns) on its five by ten inch rectangular screen. It initially sold for $3500 but a discounted price of $2640 each was offered for quantities of six.


Ad for HP 2640A terminal, Dec 1974. Click picture for full size view.

The 2644A was introduced in 1975 for $5000 and included two mini cartridge tape drives. The 2644A was replaced by the 2645A ($3,500 without tape drives, $5,100 with two tape drives) in 1976. The 2645A was the most common of the 264X terminals.


Ad for HP 2645 terminal, 1976. Click photo for full page view.

Thanks to (a private museum based in Australia and not affiliated with the Hewlett-Packard Company) for refreshing my memory on facts and features of the 264X terminal line, and for the old ads which are posted on their web site.

Related Post:  Data Terminals — Predecessors of Personal Computers, Part 2 of 2:  HP 2647A

Pam Leitterman
BS Applied Mathematics, 1975
Co-chair CS Golden Jubilee Steering Committee
President, Academy of Computer Science

Taking a Look Inside the IBM 650

Alumni Memories from Les Blumberg

I returned to Rolla in 1964 to work on my MSEE. At the time I was on an educational leave from IBM the school had provided me with an assistantship, so I spent three years working on my degree. This gave me sufficient time to assist the department in acquiring an IBM 650 from IBM. I had asked IBM for a machine we could use at the school, though my thesis was in microwave theory not computers. After many phone calls IBM agreed and sent the EE Department the machine. We placed it in one of the class rooms and then spent a number of hours attempting to get the machine up and running.  This was a plug board machine with punch cards as its input. It was a challenge, especially since IBM did not provide all of the peripheral equipment.

This is a picture of an IBM 650 — not from the university — but I’ve included it here to show how the computer looked inside.

Les Blumberg
BSEE 1962
MSEE 1966


Interior view of an IBM 650 computer

Interior view of an IBM 650 computer


Aerospace Computers and University Computers – 1960s

Alumni Memories from Bruce A. Warren

I graduated with my BSEE in 1969. I took my first programming course in 1966. I have no pictures because I couldn’t afford a camera as a co-op student working alternate semesters at McDonnell-Douglas in St. Louis and paying all my college and living expenses. I got to use the fancy aerospace computers at McDonnell (Gemini was peaking then)… some with CRT terminals and no punch cards!.

At the beginning of my college programming course, we had to turn in the handwritten code sheet and the punch card girls would type in one line on each card and we would pick up the card stack and the printout the next day. Next semester, some punch card machines were made available to students and that made fixing little bugs faster. You could  find the cards that needed editing and write the correct code on them. Then wait in line and punch up the revised cards. Put them back into the stack – in the right order – and then back to the window to turn them in for processing that night. Many days were needed to fix a single bug. The language was Fortran which I found to be very logical and sensible; especially when compared to C++ and the other programming languages I have used since then.

Bruce A. Warren, P.E.
BSEE 1969
Lake Jackson, TX