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Jan van de Veen, Nijkerk, The Netherlands



The WANG desktop calculators (1966-1978)
  WANG introduced the first programmable desktop calculator in 1966, called the 300 series. Later extension came in 1968 and special machines where made for special tasks. So, for a construction engineer a 360 would be the best choice, for other purposes there was the 370 or 380.

Calculations where done by taking the logarithm of a number. If you would like to make a division, the logarithm of the second number was subtracted from the first and by taking the antilog, the decimal number would be shown on the display.

If you would like to know more about the 300 series, please visit the oldcalculatormuseum
There is no 300 calculator in the museum, but I do have the manuals.


  In December, 1968, WANG Labs announced the new 700-series calculator to compete directly with HP's 9100 calculators. As many people who know high-tech industry understand, the announcement of a product doesn't necessarily mean it exists. Even back in late 1968, the notion of "vaporware" existed, and WANG's introduction of the 700-series was just that. Even though the product had been announced, shipments weren't promised to begin until mid-1969, which, as it turned out, was a milestone that WANG missed by a few months. In February of 1969, McGraw-Hill Publishing's Product Engineering magazine published a cover-story on the new (and not yet available) WANG 700, featuring a proud, cigar-toting Dr. Wang surrounded by a number of 300-series keyboard/display units and his new baby, a prototype WANG 700.
One of the biggest problems
WANG had with the early 700-series calculators was cooling. The electronics were really designed to be in a computer cabinet rather than a comparatively small desktop calculator. As such, the early 700-Series calculators had some pretty serious problems with overheating. Originally, the machines were designed for convection cooling, with vents in the base of the chassis and top of the cabinet. This didn't work well at all. In fact, WANG salespeople had to adopt an interesting, if bit misleading strategy to prevent potential customers from realizing that WANG had a problem with the cooling of the calculators. Salespeople demonstrating the machine at trade shows or customer sites learned quickly that the early 700-series demo calculators would start to exhibit strange symptoms after operating for around 15 minutes because they would overheat. So, they would demonstrate the amazing capabilities of the calculator for about ten minutes, then they would turn the machine off and pull off the top cabinet (fortunately, it was very easy to remove), showing off the high-tech innards of the machine, conviently allowing the machine to cool off while they were explaining the wonders of WANG's use of integrated circuit technology. After a few minutes of showing off the insides of the machine, the machine cooled enough for the electronics to be happy again, the cover went back on, and the salesperson started the spiel all over again. It soon became clear that real customers wouldn't relish having to operate their machines without the cover, so a production change was implemented, involving the addition of a good-sized fan mounted on the back of the cabinet. The fan provided forced-air cooling for the electronics, eliminating the cooling problems, but somewhat corrupting the lines of the machine, not to mention adding fan noise to what before was a silent instrument.
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In 1972 the Institute I worked for had a need for more calculation power so they could perform more complex analyses without using time-sharing. They bought a WANG 720C in  1972, together with a program to do Multiple Regression Analyses.
This picture, taken on the 21st of April 1973 at 2.30 in the morning, shows the 720, together with the dual cassette drive and the IBM-selectric printer. What can not be seen, but is there is a 708 extended memory. This black-box contained another 4K of core-memory. Added to the 2K of the 720, there was 6K all together. In a 720, you can store 256 numbers and no program, or 2048 program steps and no data and anything in between. Care had to be taken to avoid a collision of data and program. The extra memory was used for data-storage, as a Multiple Regression Analyses needs a big matrix of numbers. The program was made by WANG Belgium in Ottergem, and later modified by me. That was the moment I got a conflict between data and program !

Is soon learned to program the 720 and still today more than 40 years later, I know almost all the codes by head. A program would look like this: (it stores the value of zero in the first 100 data registers)

Step  Code   Shorthand         Explanation
0001 7000       0                   In words it means that a zero is placed in the X-register
0002 0604      UP                 and moved to the Y-register
0003 0408    MARK            A flag is set
0004 0001     0001               with label 0001
0005 0700       0                   zero is put in the X-register
0006 0504   ST.IND            and stored in the data-register who's number is in the Y-register (indirect storage)
0007 0701       1                   one is put in the X-register
0008 0600       +                   and added to the Y-register
0009 0701       1                    the number
0010 0700       0                    100
0011 0700       0                    is put in the X-register
0012 0509 SKIP X=Y         X en Y are compared. If not equal
0013 0407   SEARCH         the program jumps back
0014 0001    0001                to the flag with label 0001
0015 0515   STOP               if equal the program stops

A 720 has a X and Y register so you can step through the program and see it happen right in front of you.

If you would like to have a look into the manual that came with the 700, please click on this link
(Courtesy Mr. Bittrick)

Albuminhoud.JPG (25451 bytes) The machine that gave the most trouble was the dual cassette drive. The tapes were not formatted and you could store blocks of 1 byte up to 256 bytes in sequential order. In practice you would always use 256 byte blocks, but still there where too many problems.
The tapes where stored in albums, 12 data-tapes in an album. I still have several of these albums.

For those of you who want to know more of the technical details of the 720, please visit the site of Rick Bensene and have a look at his wonderful page about the 720

In 1974 we bought a Memorex dual 8 inch floppy-drive and a Centronix high-speed impact printer


720Cx.JPG (28976 bytes) This is the same 720C, still running perfectly, with the Memorex dual floppy drive (740-2) and the 709 tape drive.
You can clearly see the X and Y register with the nixie-tubes. The floppy drive was a wonderful extension. It was fast and reliable and gave us the possibility to do much more with the 720. Soon we had a herd-management program running for our breeding sows, hens, dairy cattle and so on. Certainly the management program for the sows must have been one of the first in the world. I later on developed a commercial sow-management  program for the 2200 and this is still widely used by thousand of farmers in the Netherlands. But, the basic idea was born on this 720 !.
In my opinion the 720C was more a desk-top computer then just a calculator. 



IBM selectric.

The 720 series needed an output device. The IBM selectric was converted to work with the 720. Amazingly there is no on/off button, it can only be switched on by sending an special code from the 720 !. It is a wonderful piece of engineering with an incredible speed and print quality. The ball shaped typing head spins around like mad. I have made two small clips with the selectric in action. In close up, the image could not keep up with the speed of the typing head but the sound is real !. Without the cover and from a further distance you can see the typing head moving along, but in less detail. It is typing the famous sentence "Now the time has come to see the quick brown fox jump over the lazy dog"

(Courtesy Mdm Föllmi, Heemstede)


  The 720 came in 3 models, A, B and C. This was the normal policy of WANG, a simple machine and also more sophisticated models.
These were expensive machines and it took not long before new, cheaper models were introduced.
If I am correct the next model was the 600, later followed by the 500 and even the 400 series.

The model on the image is a 500 with a printer on top. It has only one row of nixie tubes. The 500 is not in the museum, but I do have a number of spare boards for these machines.


This is a recently acquired C50 scientific calculator.

It has a so-called left and right calculator that do work independently.
As they share a common memory, complex calculations can be carried out without to much trouble. Of course, this machine also has special function keys that can perform pre-programmed tasks like calculating standard deviation etc.

It was even possible to link an IBM punch card reader to make small programs.

The C serie came in different configurations with or without the possibility to make small programs.



The manual is very well made. It is simple and clear and within 20 minutes you know how to work on the C50.


( Courtesy Mr Palache)



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All rights by : Jan van de Veen 
@2019   Nijkerk,  The Netherlands