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Calculators: Handheld: Anita 811
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Size (approx): | 70mm x
120mm x 23mm (w,h,d) Weight 128g excluding batteries |
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Power: |
4.5V DC, 3 x AA size batteries. Accepts an adapter/charger (no model number but it was supplied as an optional extra for both UK and US mains voltages) through socket on the top side in the middle. It is a very odd two section square socket. Charged battery lifetime was specified at up to 15 hours continuous use. Standard dry battery lifetime is quoted as 4-5 hours and alkaline as 16-17 hours. Do not use the adapter with standard batteries in place. Also, do not set the switch to battery picture whilst on adapter as this will discharge the batteries. | ||
| Case: | Leading edge or what! The main case body is a three-piece taupe coloured smooth plastic case with rounded box key surrounds. A sliding u-shaped metal back is painted gloss white on this example (I believe there were unpainted ones too). The back is pushed up to reveal the battery compartment and inner information label. A brushed aluminium wrap around panel sits in its own recess and is printed black with abstract symbols for adapter/battery power (on/off), floating/round-off and auto-memory. The red display filter sits (almost) flush and gives a clear bright image. The designer round keys are short-travel squishy type but work well. | ||
| Display: | 8 digit flat multi-point red LED with a ninth digit for negative and error indicators. | ||
| Features: | Standard four functions, percentages and two function memory. Floating and two digit switching and accumulated memory switch. Reverse Polish Notation input. | ||
| Age: | 1972 to 1974 (this example is chip date-coded for late 1973 with high board revision numbers) | ||
| Manufacturer: | Sumlock Comptometer Ltd, Uxbridge, Middlesex, UK. No serial number that I can find. | ||
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Comments:
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Lovely early design that is probably made by Adler (as it is very close to the Adler 81) who were known for their sliding back models. Nice display but pain in the neck early RPN logic. The original case is stiff brown fake leather with flip over top flap and front tuck-in band. The construction is ingenious, cramming loads into three neatly packaged boards. Every collection should have one of these. I believe there was a later version with square keys. |
| Components: | 1 x cpu: Rockwell 15330 A1030PE
7352
(date code week 52 of 1973) 42 pin staggered DIL, 0.6" width 1 x 9 digit red flat LED display 20 x transistors (9 for display drivers) 7 x diodes (4 for the power regulator and one on the keyboard assembly) 3 x capacitors 0 x resistor arrays 21 x resistors 1 x transformer |
| Boards: | The keyboard assembly (1895 PC 811 Keyboard Iss. 3 TB3606) is attached to the first (cpu) board (Ref 1970 PC Iss. 1 MAIN BD TB3754) via 16 strong wires which is attached to the second board (Ref. 1852 PC Iss. 10 TB3528 Convertor BD) via 14 strong wires in the same place. The latter board has three circular cut-outs to allow the tantalum bead capacitors and transformer to sit through and minimise the thickness. The two boards are kept apart by sliders in the main case sides. |
| Construction: | By gently pushing out the metal sides you can fully remove the u-shaped back. Surprisingly the underside of the main board is then exposed. Remove the two side screws and the base drops off (be careful not to lose the two square washers). The upper and side section then pull away to leave the keyboard attached to the main assembly. |
| Logic comments: | (C) is used once to cancel the last number entered and a second time to clear the whole calculator. |
| Input overflow is suppressed, inputting a ninth digit is ignored | |
| Negative numbers are shown with a minus in the ninth (far left) digit thereby allowing full eight digit negative numbers | |
| There is automatic constant on all four functions | |
| Divide by zero shows a "C" in the far left (ninth) digit and is not recoverable | |
| Overflow shows the result and "C" ("E" if negative) in the far left (ninth) digit and is recoverable using (C) | |
| This is a RPN logic calculator; to calculate 3-4 you enter (3)(+)(4)(-) and only use the (=) key for multiply and divide | |
| Memory use is only in the automatic mode; storage is performed by pressing the (=) key | |
| Memory storage is not indicated - you have to remember it | |
| Negative square roots are not allowed and result in an unrecoverable error | |
| The round-off switch will round up or down to two decimal places and the display is limited to two decimal points until the number gets too big |
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The manual to the left measures 120mm by 72mm and is black and white only. It is 22 pages with a fold out back page for ordering the mains adapter. It has lots of examples and tables and a very confusing description of how to use the battery/adapter/charger options. It is in four parallel languages, which I always find confusing. |
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The back sheets
contain the charger order forms for £4.40 (inclusive of VAT per unit)
made out to Sumlock Comptometer Ltd.
UK retail Sales |
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The second scan on the left shows page one as it was obviously important to boast about the single chip inside. It shows a recognisable staggered pin Rockwell chip (10563PA date code 7204) in actual size. |  |
A page shown in all manual for disposable batteries is a really useful guide to the esoteric on/off switch symbols when used with disposable batteries. |
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This is an
alternative manual for the 811 model. Printed in much stiffer
card. The back shows a Sumlock Anita Ltd and a Rockwell
International logo. 20 pp in black and white, in four languages.
It uses the same chip page as above and every page is exactly the same but missing the charger order form.
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A page shown in all manual for rechargeable as well. |
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Also included with the calculator was a cheat-sheet coated in stiff clear plastic with rounded edges. It measures118mm by 70mm to fit within the manual. It is printed in yellowish green - OK, they didn't get everything right as it is a very low contrast colour combination. I have, however, seen examples in black on the web. To the left is the rear of the sheet |
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