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Calculators: Desktop: Tokatron Tokatron

(c) Emil Dudek 2011

Size (approx): 82.4mm x 125.6mm x 30.0mm (max)  (w,h,d)
Weight 126g including excluding batteries


6.0V using 4 x AA sized batteries.  It accepts an optional adaptor (undefined but 4.5V centre negative worked OK) through a top side socket, on the far right. The manual warns that exclusive use of an adaptor should be without batteries installed.  Battery life is quoted as 10 hours for zinc-carbon batteries.
Case: The case construction is two-piece gloss, light beige plastic with a raised upper section.  A tilted display area contains a flush fitting purple plastic display filter that give a reasonable image with limited viewing angle.  The keyboard surround is slightly raised and fitted with an orange and black printed metallic panel.  The keys are very short travel but have a loud positive click.
Display: 8 digit red LED with individual bubble lenses with a ninth digit for negative indication
Features: Standard four functions 
Age: 1974
Manufacturer: Undefined, country of origin undefined, serial number 204843 on a sticker on the inside of the battery cover door


Reasonable quality feeling calculator with a keyboard area that is reminiscent of later LCD models.  Little known brand that looks like it was manufactured in a generic Far-East facility for multiple branding.  This particular brand being destined for the UK market - a nice made-up name mixing "Tokyo and electronic".  The original cover is soft black plastic with a flip-over top flap and front-popper closing. The (arithmetic) logic is very poor with no recovery and most of the common bugs.

Components: 1 x cpu: Toshiba T3171 4J (date code September 1974), 28 pin DIL, 0.6" width white ceramic package
1 x IC: Toshiba T1315B 4H (August 1974), 20 pin DIL, 0.3" width black plastic
1 x IC: Toshiba T1314 4J (September 1974), 20 pin DIL, 0.3" width black plastic
1 x nine digit LED model with integral bubble lenses, Sanyo SL-1952
0 x transistors
2 x diodes
2 x capacitors
23 x resistors
Boards: The keyboard assembly (TCK) is fixed to the front panel with 6 screws.  16 stiff wires join to the main board which is fixed to the rear section by plastic lugs. 
Construction: Remove the screws from the top edge and the case separates easily.  However, it is difficult to get full access as the short cables keep the boards together. 

Logic comments: (CE) cancels an incorrect numerical entry, whilst (C) clears the calculator
Input overflow is not suppressed, keying in a ninth digit causes and overflow error and is not recoverable
Negative numbers are shown with a "-" sign in the far left (ninth) digit thereby allowing full eight digit negative numbers
Overflow shows "" and is not recoverable 
Divide by zero shows "" and is not recoverable 
There is automatic constant on multiply and divide only
It suffers the negative zero bug: key in (1)(-)(2)(=) to give "-1" then add one by (+)(1) to give "-0"
It suffers the pseudo fixed decimal bug: key in (1)(+)(0)(.)(0)(0)(0)(=) to give "1.000" which remains a fixed three decimal point number until more digits are required or divide is used
It suffers the divide to negative zero bug: key in (0)(-)(1)(=) to give "-1" then (/)(1)(0)(=)(=)(=) etc to give eventually "-0.0000000" if you then (+)(1)(=) it will give "1.0000000", inheriting the above bug.

manual The manual measures 80mm by 124mm and is printed with an orange cover, then black throughout.  It is 12 pages in total, with the last two empty, and contains basic descriptions and instructions.

There is no country of origin, no reference numbers, and no mention of the manufacturer or brand name.

It is very similar to some of the manuals from contemporary Decimo models. See manual for Decimo Vatman X (opens new window).


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