My dad's calculators

Being an accountant, dad was interested in labour-saving calculators. Here is the first appearance of an electro-mechanical calculator in the mid-60s. The photo was taken by him in his Ampang Road office:

Unfortunately the photo was taken for the sake of the people, who I think were shareholders of the taxi company he was the secretary of, so you don't see much of the calculator. But here's another shot taken by me perhaps in 1972:

By this time he was working in his home office. (The chess player is my schoolmate. He had constructed the chessboard himself. It was actually an overturned wooden box which held the chess pieces for transport. Also notice the use of algebraic notation.) But back to the calculator. Based on the fact that it could do long division, I have determined that it's the Olivetti Divisumma 24GT described in detail here. It was already over a decade old when my dad bought one, but it took that many years to be affordable for Malaysians. By the time of the second photo, it was seldom used as he had an electronic calculator. I don't remember the Olivetti in his effects when he died in 1978 so he may have disposed of it already (university students could afford scientific calculators by 1976). There was a portable electronic printing calculator in his effects.

My dad had an older hand operated pinwheel mechanical calculator that was lying around, out of use, by the time I was old enough to poke around his office. From what I remember, it's probably this Odhner model:

You could do division by repeated subtraction.

He also had a pocket addiator which I have mentioned in this post. I never saw him use it much and it became my plaything at some point.

I seem to remember he did give me some lessons on using an abacus when I was required to learn it in Chinese primary school.  It makes sense that he would know this too.