Notes on Celestial Calculator ComparisonsStarPilot The TI-86 is designed for high school students, which means it has to be durable! Push any keys, remove batteries with calc on or off, plug into your computer on or off, no problem. Snuggled into its protective otterbox, you could drive a car over it, or submerge it to 100 feet. The calculator and program are protected by an internal backup battery. If your calculator does, however, happen to get damaged or lost, just pick up a new one in whatever corner of the globe you happen to be — the TI-86 is one of the most popular calculators in the world — load StarPilot again into your new product (no new program cost to you) and you are off. The AAA batteries are also easy to come by any place in the world. Key pad Key action is positive and clean. The key pad of a TI-86 looks a bit complex, but its use in StarPilot is very simple — only the number keys are needed for entering data. All programs are selected from a plain-language menu. No special lables are needed for the keys.
This calculator is also durable to random key pushing. To interrupt any operation, just turn it off and back on. The removal of batteries will not hurt the program, but it will erase all stored sight data in the calculator. The only special precaution is removal of the EPROM chip. This product has a removable EPROM chip on the back of the calculator that stores the program, and this vintage of calculator is susceptible to damage if the EPROM is accidentally removed with the power on. If the calculator is damaged for any reason it can be returned to the manufacturer in WA state for repair or replacement or perhaps contact promsoft who specialize in this type of calculator. The program is built into a permanent EPROM card, which has the advantage of being safe if the batteries fail — a must for units without a backup battery — but it has the disadvantage that it cannot be updated or upgraded. Key pad Keys are very sensitive but with little practice one learns to enter key stokes without double keying. Several keys have function labels, each of which executes a series of functions. The manual explains which functions are reached by which keys.
The Merlin II suffers one drawback in this area which was never much of a real problem for practicing navigators underway but it was relentlessly used against them by their competitors. The Sharp PC1248 does not have a backup battery system and the program is not in an EPROM, so it is necessary to not let the batteries go dead and to change batteries when needed within a minute or so period to avoid losing the program. The batteries only have to be changed every 5 years, or to be safe, every 3 years, but when doing so, it must be done within that period. The calc cannot sit around more than 5 minutes or so without batteries. The product comes with very clear warning and explanation of this, nevertheless, it can happen that they get put away for more than 5 years and then opened to be found dead. And, like the Celesticomp and the NC-2000, this product can only be repaired or replaced by sending it back to the manufacturer, in this case in Sydney, AU or San Juan Island in WA state. Key pad Keys are "keyless" variety that takes some adjustment since there is no real feel when pressed. We used these for years, however, and found almost no mis-keying. Keys are not labeled. Functions are run by pressing "Def" key followed by a letter, which serves as the name of the function.
Available from...
Durability
Sharp Model PC calculators
to be placed here as they arise...
Freeware and shareware Navigation and Astronomy software for the HP-48 series
Morse code for the HP-48
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AP Systems (the producer of the product)