What do the following have in common, other than they are used to calculate?


starting at the upper left corner:

1.  BOWMAR 901
4. POST 1461 6" SLIDE RULE
6. UDC "TKB 1"

You could find them all in the local tech store or university book store in 1972, maybe in the same display case!

Then of course, this showed up:

Edited: 2 May 2009, 3:31 p.m.


My guess is that they are all manufactured around 1972. BTW, 1972 was the longest year in the Gregorian calendar. As a leap year, it was one day plus an additional 2 leap seconds longer than normal.

Do I win the very nice HP-35 for the correct answer? ;-)



They all fit in a pocket?




I actually answered, well my answer anyway;

You could find them all in the local tech store or university book store in 1972, maybe in the same display case!

Cheers, Geoff


Your pictures are so nice and it was around midnight, so I just skipped your answer. Anyway, if you ever have a spare red dot remember me ;-)

BTW, the 35 looks very nice. Did you (master of restoration) restore it or were you just lucky to get such a nice item? I'm looking for information of how to restore the top silver trim. I read about bare metal foil which gives good results. Any hints you can share?



Yes, a restoration.

The silver trim is a problem, at the moment remedied with aluminum/chrome modellers paint.

I am going to experiment with chrome foil. This requires a size (base glue) be applied and then the foil placed on top. The foil is rubbed on with a cloth and the excess trimmed off.

I shall see if that works!


I tried this, Geoff, and it did not work well at all. I just used the glue that came with the foil leaf, and it didn't hold the foil well. There may be a better glue available for this particular application.


There may be a better glue available for this particular application.

What about contact cement? (But, you only get one chance to lay it on straight! Although, if you are planning to trim the excess away, that shouldn't be a problem.)


Maybe this will help:

Bare Metal Foil instructions


What do the following have in common ...

One thing the calculators have in common is the keyboard!

I seem to remember seeing these keyboards in electronics surplus stores for years. I think that they were marked "Wild Rover" or something like that.

-- Richard


Klixon keyboards by Texas Instruments before they got into the calculator business.


The Bomar 901 was my first calculator, purchased in October 1972 in Atlanta for $130 ($660 corrected to 2009). I couldn't afford the $400 HP-35 at the Georgia Tech bookstore.

I've still got the 901, but it doesn't work.


they came with hard wired 5 or 6 pack AA size nicads which by now have rotted. If your lucky the replacement would let the machine power up.

cheers, Geoff


They all use the same TI chip (TMS0103) plus a TI Klixon keypad.
The Commodore MM1 is actually a repackaged Bowmar 901.


Actually the Otis King and the Post don't have a Klixon keypad or TI chips;


but you are correct about the others......

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