T E C H N I C A L D A T A of the Mechanical Calculator CONTEX-10 *********************************************************************** Older Version Serial Number: 467645 Dimensions: (ca.) Width = 8" / 20 cm Depth = 10" / 25.5 cm Height = 4" / 10 cm Weight: (ca.) 6 lbs / 2.8 kg Mechanics: 10-Block-Keyboard, Serial-to-parallel Conversion Rocking Segment Mechanism Functions: Add, Subtract, Multiply, ( Divide ) Registers: Input = 10 Decimals Counter = 1 Decimal Arithmetic = 11 Decimals Manufacturer: BRDR. CARLSEN Gentofte, Denmark 1957 H O W T O U S E the CONTEX - 10 ************************************** ( Picture from the Operator's Manual ) OPERATING CONTROLS 1 Keyboard 5 Subtraction 9 Tabulator 2 Clear 6 Position Marker 10 Function Key 3 Multiplication & Correction 11 Control Display 4 Division 7 Decimal Marker 12 Result Display 8 Return Key START: ------ Press [C] key (2) to clear arithmetic & counter units. Shift the red slider (6) to the right to clear the input unit. ENTER A NUMBER: --------------- The actual number of digits entered are shown with the red slider (6). If wrong digits are entered, push the slider to the right to clear input. ADDITION: --------- Everytime a number is entered and the FUNCTION KEY (10) is pressed, the number is added to the content of the arithmetic unit (12). THE INPUT IS "BLIND" !!! REPEAT: ------- To enter the same number more than once, press & push to the left [X] key (3) before pressing the function key (10). The keyboard will not be cleared. To release the [X] key (3): Press & push it right. SUBTRACTION: ------------ Press [-] key (5) before pressing the function key (10). NEGATIVE RESULTS are displayed in the arithmetic unit as the COMPLEMENT of the next higher 10, 100, 1000, ... Example: -12 = 99...9988 MULTIPLICATION & DIVISION: -------------------------- Because the counter unit has only O N E decimal, multiplication & division is tricky, and needs to k e e p t r a c k of numbers either "IN MIND or ON PAPER" ... MULTIPLICATION: 123 x 45 = 5535 Press [C] key to clear arithmetic & counter units. Shift the red slider to the right. Lock the [X] key ... Enter the multiplicand (=123). The multiplicator (=45) has two digits. Press the function key as often as the figure in the "1" position - The counter will show it with its BLACK FIGURE (=5). Press the tabulator [ <- ] key. Press the function key as often as the figure in the "10" position - The counter will show it with its BLACK FIGURE (=4). The result (5535) is in the arithmetic unit. DIVISION: 22 : 7 = 3.14285714 Remainder 2 Press [C] key to clear arithmetic & counter units. Shift the red slider to the right. Enter the dividend (=22). Press the tabulator [ <- ] key as often as possible to shift it to the left. Press the function key. Enter the divisor (=07). Press the tabulator [ <- ] key as often as possible to shift it to the left. Press and lock [DIV] & [-] keys. Press the function key until the [-] key comes up (= Underflow). Press the function key again (= Addition/Correction). Read the RED FIGURE: This is the 1st digit! THE FUNCTION KEY IS BLOCKED NOW! Press the [-] key. Press the tabulator [ -> ] key. THE RIGHT DISPLAY CLEARED! Press the function key until the [-] key comes up (= Underflow) again. Press the function key (= Addition/Correction) again. Read the RED FIGURE: This is the 2nd digit! ... REPEAT ... UNTIL ALL DIGITS ARE CALCULATED ... R E M A R K S (1) T O R E S T A U R A T I O N : ======================================================================= This CONTEX-10 came with an ERROR ALSO FOUND IN OTHER CONTEX machines: The Matrix tend to stuck on the right side and had to get a left-push on the little red slider (6) to be freed for working. My SOLUTION ... Out of sheet metal ( from a fish can ) a SPRING was cut, folded and fixed in the right position by a KEY-RING. At the end of each machine cycle the matrix was pushed right - but bounced back on the spring into the right position - ready for the next operation ... R E M A R K S (2) : *********************************************************************** The INSTRUCTION MANUAL (14 pages) can be downloaded from ... http://www.rechenwerkzeug.de/Contex.zip HELP for "REPAIRING A BOHN CONTEX" can be found in ... http://www.csparks.com/contex ... together with useful links around this calculator. R E M A R K S (3) : ======================================================================= Two lines of interesting and innovative mechanical calculators came on the market under the name » CONTEX « in the '50s and '60s : The first was a key-driven adding machine in style of a Comptometer, with a "half" keyboard and simplified mechanism: CONTEX-A & CONTEX-B. The second was a series of 10-Block-Keyboard machines. This CONTEX-10 is a manual one. The CONTEX-20 is motor-driven. The CONTEX-30 has improved motor-driven multiplication and division. The CONTEX-55 has its own DIVISION REGISTER to complete the division full automatically. impressum: *********************************************************************** © C.HAMANN http://public.BHT-Berlin.de/hamann 11/15/08 |