Deciphering the Anita Calculator Model Numbers

Having been researching, collecting, studying and simulating the Anita calculators for over a year now (as I write) it had never occured to me exactly what the model numbers might mean (if anything). But, having worked in the electronics industry for a couple of decades now, it is usual for the model number to give a brief indication of the feature set of the product.

Then I purchased a Rockwell-Anita 811 SL, which as the same Rockwell I.C. found in the handheld Anita 811, but has just a few extensions in its features. So what was common and what was not? Well both are 8 digit calculators, with the basic four functions plus percant, rounding and memory. I also have an Anita 1000 LSI, which has the basic four functions, no rounding or percent and a 10 digit display. Hold on! Could the first numbers indicate the display width---8 or 10? Nigel Tout's website has references to calculators of the form 12xx, and checking these, they do all have 12 digit displays.

So what about the trailing numbers? The handheld Anita 810 is the same as the Anita 811, but with no memory. Ah ha! The last digit is a 1 if there is a memory. Checking the Anita 1011 and Anita 1011 LSI confirms this hypothesis. But, oh no! There is an Anita 1212 and 1233. Taking a look at the specs for these though, and voi la! they have 2 and 3 memories repectively.

That just leaves the middle digit, which can only indicate functions. The early models start at 1000 and are basic four function calculators. So maybe bigger middle digits add functionality. The 1010, 1011, 810 and 811 models all have rounding and percent, and so '1' could indicate this. The 1020 and 1021 have a squareroot function, but no percent or rounding. So 2 could mean 'squareroot'. The Anita 831 has both features from the '1' and '2' calculators, so one can suppose this indicates the 'addition' of these functions. The Anita 841 and the Rockwell-Anita 1041 are both enriched with scientific functions, as well as having percent and squareroots. Rounding is, however, missing, but none of the calcultors that antedate these calculators have rounding, and I think it was quietly dropped as an under-used feature. With the Anita 851 being a conversion calculator and the (perhaps never manufactured) Anita 861 being a financial calculator, the '5' and '6' digits represent these features.

There remains the issue of the suffix letters attributed to some of the models. Before the LSI models, the only suffix letter was P to indicate a printout version of the model. The next generation models had LSI attached to indicate the fully integrated circuit nature of the devices, with 'P' still used for printout variants. A 'B' was used for some models that had rechargable batteries within them. It appears that later models within this range dropped 'LSI' and gave the suffix 'D' (for display?) for the non-printing models. Once we get to the Rockwell-Anita models, a new suffix 'SL' (for 'slim line') is introduced, though this appears to have been dropped in later models. The 'P' suffix is still retained for printing calculators.

So to summarise then, Anita calculators have a model number of the form:

<display width><function><#memories><suffix>

Where the function number indicates the following:

1. Percent [and rounding]
2. Squareroot
3. Squareroot, percent [and rounding]
4. Scientific
5. Conversion
6. Financial

1. P (printout)
2. LSI (large scale integration>
3. B (internal batteries)
4. D (display?)
5. SL (slim line)

Below is a table incorporating all the models, that I can find references to and can verify the functionality of, within it. If you know of any others, or spot a mistake, drop me a line. The table is laid out so that a calculator's model number is read from the left column, then the number across the top and finally the right column.

As you can see, there are many gaps in the table, as not all variants were manufactured, but I suspect there are some missing model types. Still, one can now picture what features an 'imaginary' calculator would have, if it had existed in the product range. For example, imagine that the base model for the Anita handheld range was the Anita 800, and not the 810! I have, of course, no direct evidence to the validity of all this, but is just a conjecture and a bit of fun.

Rockwell calculator postscript

Once we reach the Rockwell handheld calculator range, I can discern no such watertight regularity. All have 8 digit displays, but '8' does not figure in the model numbers consistently. I have conjectured (for the 21R and 31R) that the '1' indicated internal rechargable batteries (the 20R and 30R models use a 9V dry cell). The 51R and 61R also have rechargable batteries, and in addition the 51R matches the functionality of the Anita 851 (indeed they share the same Rockwell IC). However, the 10R, 8R and 18R and muck up any hope of a consistent model numbering scheme, and the 20R and 30R have different functions from the '2' and '3' function numbers of the Anitas. The suffixes do (mostly) seem to indicate the 'seller', so that 'R' models are Rockwell calculators whilst the 9TR was made for 'TRu value' stores and the House of Fraser models use 'F' (for Fraser?) or 'HF' (on later models). The Sears & Roebuck '8M' and Radio Shack EC220/EC440 models, of course, blow that theory out of the water! Maybe they had their own model number schemes already. Then again, some of the later Rockwell models with VFD displays started using RD, before T, K and KII came into play! I suspect that Rockwell International had a more 'proactive' marketing department than the more traditional Sumlock Anita (but at least you knew where you were).

Simon Southwell

1st December 2004

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