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Calculators: Handheld: Rockwell 10R

Size (approx): 76mm (max) x 140mm x 22mm (max)  (w,h,d)
Weight 116g excluding batteries


9.0V DC, 1xPP3 size batteries.    Also accepts adapter (Part No. 331 R03-001 for the US 110V-120V) through top end socket on the left. 
Case: Sturdy stippled brown plastic case with light beige keyboard surround.  Red display cover shows a clear view of the numbers.  Squashy but positive lozenge-shaped keys work well.  The raised Rockwell logo and two vertical edges are painted silver and have survived very well on this example.  Fatter shape than most Rockwell calculators of this period by being about 15mm shorter than the norm. The on/off sliding switch is on the right hand side midway up.
Display: 8 digit red LED with bubble lens with no ninth digit.  
Features: Four function 
Age: 1974
Manufacturer: Rockwell International, Microelectronic Product Division, Anaheim CA 92803.   Assembled in Mexico, US and Foreign parts. Serial No. 105148


Lovely atypical USA Rockwell calculator with sound logic and clear display.  Only let down by the limit of seven digit negative numbers.  I presume that the key labelling is kept deliberately minimal:  the (C) key should be (CE/C) and the "-" key should be (-=).  Both the silver trim and any lettering on the keyboard surround have a tendency to rub off so finding good examples is not easy.   Original case is padded brown plastic with flip top cover and tuck-in tab at the front, embossed with Rockwell.

Components: 1 x cpu: A5000PA 7448 (week 48 of 1974) 42 pin DIL 
1 x 8 digit (nine bubble lens) LED unit 
0 x transistors
0 x diodes
10 x resistors
2 x capacitors
1 x transformer Paktransformer AA1224A
Boards: Keyboard unit is attached to the main cpu board via eight pins into sockets on the bottom and side of the main board.
Construction: Remove the four screws on the back.  Gently push out the front keyboard which hinges up from the display surround.  Pop off the display surround by using gently pushing a blunt object through the three slots on the rear.  The area above the display has a piece of matt grey card so that light does not show through the upper part of the red plastic cover.

Logic comments: (C) cancels an incorrect numerical entry, pressing a second time (C) clears the calculator
Divide by zero shows "" whilst overflows are shown with the answer and all points alight. The error is recoverable by use of (C)
Minus sign is shown on the immediate left hand digit which limits the calculator to seven digit negative numbers
Input overflow is suppressed, typing in nine digits ignores the last one
It has automatic constant on all functions

10R Manual

Small manual measuring 128mm x 68mm has colour cover (including inside diagram) and 32 additional one colour black printed pages.  Back states "Rockwell International ... where science gets down to business".  Ref 2520-D-63-R1-408, Litho in the USA.  Stated copyright of 1974.

Excellent in depth manual with advert in the middle for the whole range that year; 10R, 20R, 30R, 51R, 61R and 80R.