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Calculators: Desktop: Adler 1216 (aka EC-31) (aka Triumph-Adler 1216)

(c) Emil Dudek 2011

Size (approx):

176mm x 240mm x 66mm(max) (w,h,d)
Weight 1,214g excluding power cable/plug


Mains (240V,  50/60Hz, 2.8 Watts) power through a two-pin plug. This enters the calculator on the top edge, in the middle. 
Display: 12 + symbol digit blue/green VFD, the symbol section indicating overflow, negative and memory indication.  Thousands indication.
Features: Standard four functions with constant memory, item count, square root, register exchange, percentage,  and five function memory.  Switched memory accumulation mode, switched fixed decimal modes and switched percentage modes. Semi-RPN logic. Dual-display item count.
Age: c1976
Manufacturer: Adler: T-A Vertriebs-GmbH, D85 Nürnburg, Germany.  Made in Japan.  Serial number 65587240N.


Big mains desktop with extra digits and an interesting range of functions; I especially like the "second memory" constant which is very flexible and the dual display mode for the total items count. Appears to be quite rare but have seen the Triumph model and the rechargeable "AD" version..

Case and Design: The case is made from smooth/textured black and beige plastic body sections. The whole case has a light tilt to it which can be increased with a rear metal leg.  A heavily inset green plastic display filter (with printed white numerals and item-count indication) gives a well-shielded and readable image.  The top area has a black printed metallic logo sticker which sits in its own recess and a considerably inset on/off switch.  This top area also has a number of cooling vents.

(c) Emil Dudek 2011

Keys and Switches: Big chunky keys with long travel and a hollow loud clunk and bounce. Colours are used to differentiate the functions.  The left slide-switch have silver painted raised lettering whilst the upper switch and keys have a black printed brushed aluminium panel set in its own recess.  
Construction: From underneath, remove the four screws. From the rear, the back will come off easily.
Boards: The main board (1216N-240402C) lies face down on top of the keyboard assembly. The two are joined by a 20-way ribbon cable and an earth wire. The two top screws hold down the main board which is supported by sturdy metal brackets. The display is mounted on it's own mini-board (1216-340403D).

The Omron IC is a branded Hitachi chip. At first glance it looks like the ICs are date-coded 1976 which would tend to imply that this design was rather archaic in its day.  It has the same IC profile as the Adler 1218.

Components: 1 x IC: Omron HD32614P 6K15 40 pin DIL 0.6" black plastic
1 x IC: Hitachi HD36117 6J31 36 pin DIL 0.6" black plastic
1 x 12+1 digit VFD unit (glass flat faced)
1 x transistors
18 x diodes
7 x capacitors
4 x resistor arrays
2 x resistors
0 x voltage converter F22
1 x transformer T0-7 30W6ZD8508501-2A
3 x fuses

Logic comments: The (C) key will also clear the last number entered, so it is a (C/CE) key really
The display is left-leading with leading and trailing zero suppression
Input overflow is not suppressed, keying a thirteenth digit causes and overflow which is not recoverable
The logic is semi-RPN (Reverse Polish Notation), to do 5-2 key in (5)(+=)(2)(-=)
Negative numbers are shown with a minus sign in the far left symbol cluster thereby allowing full twelve digit negative numbers
Overflow shows the shifted result and "<-" in the far left symbol cluster and is recoverable using (C)
Divide by zero is not flagged and results in zero!
Square roots of negative numbers are allowed and result in a positive number
The selectable constant is really just an extra memory to store your constant operator: (Kin) stores it, (RK=) recalls it and (KD) displays it,  repeated pressing of (RK=) will perform a Recall-add-to-register allowing you to use multiples of the constant
There is a sliding switch to select between "0,1,2,3,6" fixed decimal places, "F" for fully floating and "AM" for financial mode; where keying (5)(9)(9) will result in the entry of "5.99"
There is a sliding switch to select between percentage modes: % for normal use, TAX, Delta, Mark-up and Mark-down are also included.
Memory store is by use of the (M+=) and (M-=) with two other functions for memory recall (Mout) and memory clear (CM). 
Memory store is indicated by a small "M" in the far left symbol cluster
Overflow in memory is flagged, is recoverable by use of (C) and the memory maintains the shifted product
The (n) switch switches on the item count and rather neatly divides the display into a 10+2 system, so you can keep track of the item count at all times
There is a sliding switch above the memory keys to switch on the auto-accumulator "A": the result of every multiplication or division is added to the memory
It suffers the divide to negative zero bug: key in (1)(+=)(2)(-=) to give minus one, now divide repeatedly by 10 to eventually get "-0."

Footnotes: Thanks Serge: there is a Triumph 1216 that looks exactly the same, an Adler 1216 AD that looks the same but with a rechargeable battery, and another Adler 1216 with a different upper key configuration.  No doubt there are more variations.