Texas TI-33

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Calculators: Handheld: Texas Instruments TI-33

	Size (approx):	80mm (max) x 145mm x 35mm (max) (w,h,d) Weight 108g excluding batteries
	Power:	9.0V DC, 1xPP3 size battery. Also accepts adapter kit (RK3 which includes a rechargeable battery) through right hand side socket, midway. Alkaline battery life is quoted as 20hrs
	Case:	Typical bulging Texas shape with a slightly squeaky case. Buttons have a solid click for easy entry. Made from stippled black plastic with brushed aluminium keyboard surround painted. Texas logo is proud and painted silver, with silver painted display fake-escutcheon.
	Display:	8 digit LED with bubble lens (plus one for minus sign)
	Features:	Square root, reciprocal, square, pi. The functions Sin, cos, tan, log, lnx and y-to-x are inverted by use of the INV key. EE or INV EE switches between 8-digit calculator and scientific (5+2) and back. Right arrow key briefly shows any scientific-format number as full eight digit. Sign change, parentheses, constant, Degree/radian/grad mode and three full function memories make this a sophisticated calculator. EXC exchanges memories or display with memory.
	Age:	1978
	Manufacturer:	Texas Instruments, assembled in Italy. Serial number 2979RCl
	Comments:	This must have been the business in its day. Large battery compartment implies that the rechargeable battery must have been quite a bit bigger. This particular model has a blanking plate over the mains adapter input which may be a home-made revision. Automatic power save and switch off mode is useful.

Components:
Boards:
Construction:

Logic comments:	ON/C is press once to switch on, once to clear an incorrect number entry and twice to all clear.
	A complex table is given in the manual to show what keys presses are needed to clear an incorrect operator!
	An error results in the display "Error" in the first five digits. No error is recoverable - not very forgiving, the manual says start over!
	Minus sign is shown to the immediate left of a number but can travel into the ninth digit allowing full eight digit negatives.
	There is no indication of memory - you have to remember it.
	All memory functions are two key; (Mn)(+) stores with add, (M)(=) recalls a memory, (M)(On/C) clears a memory.
	You cannot enter first operator greater than 1 x 10 [99], it has to be a second one - Weird!
	Internal accuracy is to 11 digits even though only 8 are displayed. Subtract the eight digit number to find the extra bits.
	A power save function (on mine after 28 seconds) switches the display into travelling decimal point to the right. Recovered by pressing EXC twice. After ten minutes it will power down completely.
	The ninth digit is used to indicate trigonometric modes; "I" for Radians and "II" for Grads.
	It has constant function using the (K) key used after the operator. Can also be used on y-to-x and x-root-of-y.

	This lop-sided looking box (honest it's an optical illusion) was about the same size as the calculator at 160mm x 80mm x 38mm (H x W x D). Probably faded such that it looked more like the manual originally. Rear of the box lists the 15 world-wide service centres and states that it is printed in Italy.		The manual is also about the size of the calculator at 152mm x 75mm (H x W) and is stapled to hinge from the top. At 88pp including the four process colour cover this is quite a beast. All inner pages are one colour black. This copy also has a loose Erratum sheet which corrects some errors in the description of operator priority in calculations. Printed in Italy, Ref No, M.Om 393 387 S and 1103509-2, but no date of copyright.