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Calculators: Handheld: Rockwell 8R

Size (approx): 75mm (max) x 155mm x 23mm (max)  (w,h,d)
Weight 120g excluding batteries

Power:

9.0V DC, 1xPP3 size battery.  Also accepts adapter (undefined) through top end socket on the left. There is an on/off sliding switch on the left hand side about half way up.
Case: Sturdy stippled brown plastic case with light beige keyboard surround.  Red inset display cover.  Lovely lozenge-shaped keys in chocolate brown have a positive click and work well.  The raised Rockwell logo and two vertical edges are painted silver.
Display: 8 digit LED with bubble lens
Features: Four function plus percentages. 
Age: 1975/6
Manufacturer: Rockwell International, Microelectronic Product Division, Anaheim CA 92803.  Made in Hong Kong.  There appears to be no serial number.
Comments:

 

A classic looking calculator made a little frustrating by the seven digit limit to negative numbers and the equals button placed at the top right, rather than the easier bottom right.  This calculator was also built as the House of Fraser model 8F in a dark blue case with white buttons and the Radio Shack EC-220 in beige and white.

Components: 1 x 9 digit bubble lens LED module
Boards: Keyboard assembly is attached to the main board by soldered connectors around two edges.  It is impossible to get access to the main board without de-soldering the nine pins.  Other models like the 21R used the pins self located into sockets for easy removal.
Construction: Remove the four screws on the back.  Gently pull out the front keyboard which hinges up from the display surround.  Pop off the display surround by pulling it upwards. Main assembly can be removed by slightly twisting away from the on/off switch.

Logic comments: (CE) cancels an incorrect numerical entry, pressing a second time (C) clears the calculator
An error results in the display lighting up all decimal points  Error is recoverable by use of (CE)
Minus sign is to the immediate left of a number, thereby limiting you to seven digit negative numbers.
Input overflow is suppressed, typing in nine digits ignores the last one
It has automatic constant on all functions