Silver Reed 98

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Calculators: Handheld: Silver-Reed 98

		Size (approx):	77mm x 127mm x 25mm (max) (w,h,d) Weight 122g excluding batteries
		Power:	3.0V DC, 2 x AA size batteries. Accepts an adapter/charger (DC 3V, 0.3W) through a socket on the bottom side, on the far right.
		Case:	Solid feeling calculator with rounded top and bottom. The case is two-piece smooth black plastic with a prominent groove either side. The green plastic display filter is flat and flush, giving a good bright image. Below this is a black printed metallic sticker with the brand and model number. The keyboard surround is brushed aluminium which sits flush with the case. The keys are medium travel and quite springy.
		Display:	8 digit green VFD with a ninth digit for negative and memory indication
		Features:	Standard four functions with percentages, square root, squares, reciprocal, change sign, brackets and four-function memory.
		Age:	est. 1975
		Manufacturer:	Silver Seiko International, Frankfurt, West Germany. Made in Japan. Serial No. 921759 is on the inside of the battery cover.
		Comments:	Solid calculator of the no nonsense variety with some useful extra functions. The logic is OK with good recovery but let down by negative roots and the pseudo fixed decimal bug. Original case is soft black plastic with open top and lowered sides for access.

Components:	Suspect a Rockwell main IC
Boards:
Construction:	Cannot find an easy way to open it has the sides are too stiff to easily pop off the internal lugs.

Logic comments:	The (C/CE) key is used to once to cancel the last number entered whilst a second press clears the whole calculator
	Input overflow is suppressed, inputting a ninth digit is ignored
	There is automatic constant on all four functions
	Overflow shows the result with all decimal points alight and is recoverable using (C/CE)
	Divide by zero shows "0.0.0.0.0.0.0.0.” and is recoverable using (C/CE)
	Negative numbers are shown with a "-" in the far left (ninth) digit thereby allowing full eight digit negative numbers
	You can use the change sign function in mid number entry
	Square roots of negative numbers are allowed and result in a negative number
	Memory store is indicated by the decimal point of the far left (ninth) digit
	It suffers the pseudo fixed decimal bug: key in (1)(+)(0)(.)(0)(0)(0)(=) to give an answer of “1.000” which remains a fixed three decimal number until more digits are required or you use multiply/divide/subtract