Harvard H-303

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Calculators: Handheld: Harvard H-303


		Size (approx):	70mm (max) x 134mm x 24mm (max) (w,h,d) Weight 68g excluding batteries.
		Power:	9.0V DC, 1 x PP3 size battery. Also accepts adaptor/charger (undefined) through a left side socket about a third of the way down.
		Case:	Cheap feeling two piece shiny black plastic case. Edges are a bit sharper than you would normally expect. It has brushed aluminium panels for the brand / model info above the display and keyboard surround below. The flaring that you can see above the word "Student" is the original sticky-back plastic coating. The body is titled up towards the back and widens at the top to accommodate the 9V battery. Cheap battery terminals are just two metal tags rather than a proper 9V battery connector. The red plastic display filter is flat and flush but gives a decent, if narrow view. Buttons make a positive loud click. Blue and black colour scheme of keys reminiscent of a Texet calculator. On/off sliding switch on the right side, in line with the display.
		Display:	8 digit red LED with bubble lens display - ninth used for minus sign.
		Features:	Basic four function with percentages, change sign and four-function memory.
		Age:	1981
		Manufacturer:	Serial Number 0759598. Made in Hong Kong.
		Comments:	The fact that this calculator has a CS button for change sign means it is very very likely to be a Texet calculator. Cheaply made but works well enough. Logic quite robust except for the pseudo fixed decimal bug. See the Same Calculator page for more clones.

Components:	1 x IC Texas Instruments TMS0972NL NBT8114 (week 14 of 1981), 28 pin DIL, 0.3" width black plastic 1 x 9 digit LED display with integrated bubble lens
Boards:	One main board, floating in a couple of plastic pillars.
Construction:	Difficult to open as this was never designed to be repaired. There are numerous plastic lugs along all the edges. Best success was found starting at the top pushing the upper section inwards. If in doubt -don't do it!

Logic comments:	The Clear Entry key (CE) is used to clear an input number, the clear (C) key is used to completely reset the calculator
	Overflow on the input of a number is suppressed
	The constant function is automatic on all four operations
	The negative sign is shown on the immediate left digit pushing into the ninth to allow 8-digit negative numbers
	There is no indication of memory storage - you have to remember it.
	Overflow errors are shown as a flashing number which are recoverable by use of the (CE) key.
	A divide by zero or overflow error is shown as a flashing "0" which is recoverable by use of the (CE) key.
	It suffers the pseudo fixed decimal bug: key in (1)(+)(2)(.)(0)(0)(0)(=) to get "3.000" which remains a three digit fixed decimal until more are needed or you use multiply or divide.

	This box is calculator-sized at 155mm x 83mm x 34mm and printed in full four-colour process. Also says Made in Hong Kong, but no other details.