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Calculators: Handheld: Rockwell 64RD

Size (approx): 86mm x 150mm x 24mm  (w,h,d)
Weight 152g excluding batteries


4.5V DC, 3 x AA size batteries.  Accepts an adapter/charger (undefined centre positive) through socket on the top side in the middle.  The four-AA sized battery compartment has a plastic post to allow you to insert three batteries only.
Case: Sturdy stippled brown plastic case with light beige keyboard surround.  A neutral display filter is flat and flush, showing a clear view of the numbers though a window.  Squashy but positive keys have extra labels printed in black on the keyboard surround.  The raised Rockwell logo and two vertical edges are painted silver and are prone to wear.  The model number is printed on the lower keyboard surround in dark brown. There is a large metallic sticker on the back which is crammed with instructions.
Display: 8+2 digit blue VFD display with a ninth digit (and intervening one) for the minus signs.  Display input starts at the left rather than the normal right.
Features: Standard four functions, square root, squares, change sign, trigonometric, logs, powers, reciprocal, pi,  scientific notation, polar-rectangular coordinates, parentheses, DMS conversion, register exchange and three function memory.  Switch for degrees, gradians and radians.
Age: 1976
Manufacturer: Rockwell international, Microelectronic Product Division, Anaheim, California 92803.  Made in Japan, serial number 113072.096.


Classic Rockwell design a little larger than most with a useful array of scientific functions.  However, with no recovery, strange (EE) key isolated function and lack of cancel (INV), the logic could be better.  The original case is thin soft black plastic with a flip over top flap and front tuck in band.  Two cuts in the back allow it to be worn on a belt.

Components: 1 x cpu: Rockwell A4806CB 7644 (date code week 44 of 1976) 42 pin staggered DIL
1 x 12 digit VFD unit, single glass tube flat face
2 x transistors
5 x diodes
6 x capacitors
2 x resistor arrays
9 x resistors
1 x transformer DCT-06B Zebra
Boards: The keyboard assembly (GICO 51.9.27) sits on top of the main cpu board and is held in place by the 24 joining wires. The cpu board is held in place by the battery terminals. 
Construction: Remove the display plastic first by gently levering out the sides and pushing the lugs that can be seen at the top.  Quite difficult to be very careful.  Then repeat the process with the keyboard surround.  You will never believe the number of cracked cases I have seen on these so if in doubt - don't bother.

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
The display mode is always scientific unless you are in input mode: key in (6)(=) will show "6.0000000 00"
Negative numbers are shown with a minus in the ninth (far left) digit thereby allowing full eight digit negative numbers.  Negative exponents in the intervening digit.
There is automatic constant on all four functions
Divide by zero shows a ". .0.0."  and is not recoverable
Overflow shows a ". .0.0."  and is not recoverable.  This is also what happens when you underflow by dividing to zero: key in (1)(EE)(9)(9)(+/1) to give "1.0000000 -99" then (/)(1)(0) will give ". .0.0.".
The change sign function can be used in mid number entry but not before
Memory storage is not indicated - you have to remember it
Memory clear is by storing zero: (0)(STO)
Overflow in memory stores the original number
Negative square roots are not allowed and result in an unrecoverable overflow
The extra functions are accessed by first pressing the (INV) key, but you cannot cancel it
The "EE" key used in isolation creates some strange result try (9)(=)(EE) to give "1." with an exponent of "00"