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Calculators: Handheld: Rockwell 44RD

Size (approx): 75mm x 155mm x 23mm  (w,h,d)
Weight 134g excluding batteries


4.5V DC, 3 x AA size  batteries.  Accepts an adapter / charger (undefined but 4mm plug) through socket on the top side at the far left. The first battery slot must be left empty.
Case: Sturdy stippled brown plastic case with light beige keyboard surround.  Neutral display cover shows a clear view of the numbers.  Squashy but positive keys work well.  The raised Rockwell logo and two vertical edges are painted silver and have not worn well in this example.  The model number is printed on the keyboard surround.
Display: 8 digit blue VFD display with a ninth digit for the minus sign.  Display input starts at the left rather than the normal right.
Features: Standard four functions, square root, change sign, trigonometric, logarithms, exponential (powers and roots), squares, reciprocal and pi, scientific notation, parentheses and two function memory.  Switch for degrees and radians.
Age: 1976
Manufacturer: Rockwell international, Microelectronic Product Division, Anaheim, California 92803.  Made in Japan.  Serial No. 103816.096


Classic Rockwell shape made that bit more desirable by the sophisticated functions - top notch model of the day.  Original case is black leather-effect with flip over top and tuck in band.  Built to last with solid logic.  There was a branded version; the House of Fraser 44HF

Components: 1 x cpu: Rockwell A6500CA 7606 (date code week 6 of 1976) 42 pin staggered DIL
1 x 9 digit VFD flat panel glass faced display
2 x transistors
4 x diodes
6 x capacitors
2 x resistor arrays
7 x resistors
1 x transformer
Boards: The keyboard assembly (Ref 20260923) is attached to the front of the calculator via 12 screws and to the cpu board (Ref. IL-6500) via 18 strong copper wires. 
Construction: Very gently poke a blunt pointed object through the two holes at the bottom of the rear side.  Squeeze apart the sides and this will pop out the keyboard surround.  Do the same through the top three holes for the display cover.

Logic comments: (CE/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 ""  and is not recoverable
Overflow shows a ""  and is not recoverable
Memory storage is not indicated - you have to remember it
Negative square roots are not allowed and result in an unrecoverable error
nth root of m is calculated by  (m)(Yx)(n)(1/x)(=)

44RD Manual

The manual on the left measures 72 x 136mm and  contains 24 printed pages.  The inside pages are one colour black.  It contains instructions in English, German, French and Spanish.  Simple example instructions work ok.  The first few pages are split per language but then you have to put up with four lines of text for each example.  There are a few English spelling mistakes that make me believe this has been converted from the Japanese. Ref. 2520D-124 NEW1-76 (1226R12-001).