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Calculators: Desktop: Adler 1218 (aka EC-53) (aka Triumph-Adler 1218)

(c) Emil Dudek 2011

Size (approx):

181mm x 248mm x 60mm(max) (w,h,d)
Weight 1,195g (1,365g including cable and UK three-pin plug)


Mains (220-240V,  50/60Hz, 30 Watts [surely this is an error and should be 3.0 watts?] ) power through a two-pin plug-in cable (of good length). This enters the calculator on the top edge, in the middle. My example has a supplementary sticker near the mains cable input, which may be for UK models only, which states: "Power: 240V +/- 10%, 50/60Hz".
Display: 12 + symbol digit green VFD, the symbol section indicating overflow, negative and memory indication.  Thousands indication.
Features: Standard four functions with constant memory, item count, square root, percentage,  and four function memory.  Switched memory accumulation mode, switched fixed decimal modes and switched percentage modes. Semi-RPN logic. Dual-display item count.
Age: 1978
Manufacturer: Adler: T-A Vertriebs-GmbH, D85 Nürnburg, Germany.  Made in Japan.  Serial number 70684545.


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. This was a member of a series of three calculators, including the 807 and 1217 models and there was a 1218P model (which looks very different) that was a printing version.

Case and Design: The case is made from smooth dark brown and cream plastic body sections and a textured top dark brown keyboard surround. 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 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.  A number of slide-switches have silver painted raised lettering.  The (n) key is a push-on/push-off type.  
Construction: From underneath, remove the two screws at the bottom and the two on the top edge of the calculator.  Carefully turn it over, remove the three sliding switch knobs and the front section will lift off.
Boards: The metal-framed keyboard assembly sits on top of the main board guided by some plastic lugs and pillars. This is joined by a 20-way ribbon cable and an earth wire to the main board.  This main board (841213) is fixed to the rear of the case by plastic lugs.

The Omron IC is a branded Hitachi chip. At first glance it looks like the ICs are date-coded 1978.  This would appear to be rather archaic design.  It has the same IC profile as the Adler 1216.

Components: 1 x IC: Omron HD32614P 8D15 40 pin DIL 0.6" black plastic
1 x IC: Hitachi HD36117 8B35 36 pin DIL 0.6" black plastic
1 x 12+1 digit VFD unit (glass flat faced) Itron FG-139F6 LHA
2 x transistors
14 x diodes
11 x capacitors
2 x resistor arrays
10 x resistors
1 x voltage converter F22
1 x transformer 8508501-2A
1 x fuse

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) key (or rather 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: 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."