How a 1974 Sinclair Scientific calculator works

Found 1974 Sinclair Scientific calculator workings link.
http://hackaday.com/2013/08/30/ken-shirriff-completely-reverse-engineers-the-1974-sinclair-scientific-calculator/

Article here. Hackaday says - Read it now. http://files.righto.com/calculator/sinclair_scientific_simulator.html
http://en.wikipedia.org/wiki/Sinclair_Scientific

Great stuff with history, schematics and code. Reading the stuff in the article about how multiplication worked in the TI TMS 080x
http://datamath.org/Chips/TMS0803.htm ,
realized it was like a mechanical calculator,
http://en.wikipedia.org/wiki/Mechanical_calculator ,
and it struck that it might be an interesting project to actually make a mechanical scientific calculator. Never thought about possibility before.

Starting point would be some common manual mechanical calculator like -
http://en.wikipedia.org/wiki/Odhner_Arithmometer
Interestingly the most commonly produced of these are so common - though unseen in the modern era of electronic calculators - as to have practically no antique value - and can be obtained for little money (unless you want to start with a rare Curta). http://en.wikipedia.org/wiki/Curta

Arithmometer pretty much works like the ALU math http://en.wikipedia.org/wiki/Arithmetic_logic_unit in the TMS0803/Sinclair... with a little help from the user during shifting. A Monroe has capability for automatically doing the shifts for multiply and divide... making it a four function mechanical calculator
http://www.hpmuseum.org/ffhand.htm
http://en.wikipedia.org/wiki/Monroe_Calculator_Company

The relation of the TI chip to four function mechanicals may not really be an accident. Note the connection to Busicom http://en.wikipedia.org/wiki/Busicom
- who was making arithmometers when they partnered with Intel to make the 4004 microprocessor.

So then one needs registers (there are only two in most mechanicals - not counting a "check" counter in some) and an instruction cache of some sort (to get the micro code for shifts and such). And some glue/flow mechanisms to stick the whole thing together. Of course one might consider these solved problems if one considers a pad and pencil to be RAM and a calculator manual (or other paper documented process) to be ROM, but part of the point of a calculator is to automate or mechanize as much as possible, to take human error out of the process.

Homographs and Search

One of the biggest problems for search is homographs.

http://en.wikipedia.org/wiki/Homograph

Especially problematic are IT domain homographs, when one actually wants to find the real world item.

Examples:
Ethernet switch - where the term switch means things with sets of contacts with a mechanical actuator to change the set of contact positions http://en.wikipedia.org/wiki/Switch – and where instead one gets the IT term related to protocol switching (hubs, repeaters, bridges and routers). My best attempts were to replace Ethernet with RJ45 or TCP/IP and to add the term “selector”, “rotary” or “contact” or other physical specifier. The same problem largely applies to any “network-type” switch (optical, packet, etc.) when one is looking for an on/off, disconnect, or manual selector for that media.

Big data for mining – where the term mining means the mining (coal, precious metals) industry http://en.wikipedia.org/wiki/Mining – and where instead one gets the IT term for data mining. My best attempts were to search for physical/resource mining and then use their search engines to back into big data. http://www.mining.com/

3D model – where one means physical (real world instantiated) model http://en.wikipedia.org/wiki/Physical_model – and one instead gets the IT terms related to computer aided design (CAD) and virtual 3D modeling. Even refining and adding 2D from 3D or “physical” gets many of the same references to CAD. And there is an additional “fashion model” ambiguity as well. The real and virtual model discussion are now so closely connected that there does not seem a good way to differentiate. Discussions related to 3D printing seem to have a good way of segmenting the topic by materials used. But if a 3D model is made of /paper/ then the world of CAD printing gets mixed with the world of real 3D physical models made of paper/card.

Interestingly enough:

Search – where one means looking in the real world for a person/place or thing (Oddly Wikipedia does not even have a page for old-school “search” as in search and rescue or finding lost people/places/things) – and one instead gets the IT terms related to web or Internet search. Searching for the problem of homograph search is itself a homograph search problem.