Rockwell 9TR

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Calculators: Handheld: Rockwell 9TR

	Size (approx):	75mm (max) x 155mm x 23mm (max) (w,h,d) Weight 122g 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 dark green plastic case with light beige keyboard surround. There is an oversized stippled red inset display filter with a smooth window. It has a raised Rockwell logo painted silver. Lovely lozenge-shaped keys in olive green have a positive soft click and work well. The keyboard surround is printed in olive green for the key labels and a designer line. It does not have the model number printed on the lower front or lower edge like Rockwell usually did.
	Display:	8 digit LED with bubble lens with no ninth digit.
	Features:	Four function plus percentages.
	Age:	1975
	Manufacturer:	Rockwell International, Microelectronic Product Division, Anaheim CA 92803. Assembled in Mexico, US and Foreign parts. Serial number 228220.
	Comments:	Wow, a Rockwell 8R in green! This was made for the US chain store True Value. 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.

Components:	1 x cpu: Rockwell B5000CB 7548 (week 48 of 1975), 42 pin staggered DIL, 0.6" width 1 x 8 digit bubble lens LED module 2 x capacitors 2 x resistors
Boards:	Keyboard assembly is attached to the main board (20167D67-03) by 9 protruding wires that slot into long sockets on the main board.
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 whilst gently pushing a blunt object through the slots at the top of the rear.. Main assembly can be removed by slightly twisting away from the on/off switch.

Logic comments:	(CE/C) cancels an incorrect numerical entry, pressing a second time clears the calculator
	Input overflow is suppressed, typing in nine digits ignores the ninth
	There is automatic constant on all four functions
	Divide by zero results in "0.0.0.0.0.0.0.0." and is recoverable by using (CE/C)
	Overflow shows the result with all decimal points alight and is recoverable using (CE/C)
	Negative numbers are shown with a minus in the digit to the immediate left of a number but as there is no ninth digit to travel into you are limited to seven digit negative numbers.