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Texas Instruments TI-58C Pool Water Analysis

Date of introduction:	1979	Display technology:	LED-stick
New price:		Display size:	10 + 2
Size:	6.4" x 3.2" x 1.5" 162 x 81 x 37 mm³
Weight:	8.5 ounces, 240 grams	Serial No:	7183855
Batteries:	BP1A	Date of manufacture:	wk 17 year 1979
AC-Adapter:	AC9131	Origin of manufacture:	USA (ATA)
Precision:	13	Integrated circuits:	TMC0501E, TMC0591, CD2400, CD2401 TMC0573
Memories:	0-60
Program steps:	480-0	Courtesy of:	Mark Bollman

The main disadvantage of the TI-58, the non-permanant program storage was corrected with the TI-58C. Using a low-power C-MOS memory (an unknown chip in this machine) battery drop caused by the NiCd's itself was quicker than drop caused by the memory.

The TI-58C continued the usage of the Solid State Software Modules™ with up to 5000 program steps introduced with the TI-58 and TI-59 already in 1977. On the backside of the TI-58/59 you'll notice a small lid with a place for a module. The Master Library with 25 different programs was included, a lot of other modules were available.

We know four different approaches of the module expansion:

	Standard modules like the Master Library use only the small sticker above the A,B,C,D, and E keys.
	Other modules like this Pool Water Analysis developed by Olin Corporation make use of a colourful keyboard mask.
	Customized calculators like the USMC AV-8C calculator or insurance calculators sold by Allianz and others use special keyboard arrangements.
	The CAL-Q-TAX calculator uses an extender instead the usual drop-in modules.

Dismantling the Pool Water Analysis calculator reveals a standard TI-58C calculator manufactured in Spring 1979. It is one of the very early models, the printed circuit board (PCB) of the calculator was manufactured in Canada and makes use of some blue wires.

The calculator was available till the year 1983.

If you have additions to the above article please email: joerg@datamath.org.