Calculators and handheld computers consumed what time I might have spent with the marmot yesterday and Sunday, though I did sit in on the Tinderbox meetup on Sunday.
I need to correct something I mentioned on Saturday. I had the impression that the TI-89 series used a Z-80 processor and that's not the case. It used the Motorola 68000, as did the TI-92. The 89 was basically the 92 without a QWERTY keyboard, which apparently made it acceptable in some classroom settings where the 92 wasn't permitted. I knew they are largely feature identical, (the 92 has a larger screen) but seemed to recall being somewhat surprised to learn the 89 had been supposedly developed using the Z-80. I don't know where I got that impression, but it's false and I wanted to correct my error.
In other news, I also mentioned NTDS on Saturday, and it seems much, if not all, of the text of a book on the history of NTDS, When Computers Went to Sea, is available online as a web site. Even if you're not interested in NTDS, chapter two (link at the bottom of chapter one), has a nice capsule history of computer development. It also offers a more nuanced view, crediting Eckert and Mauchly with the "stored program" design of a general purpose computer, something that has historically been credited exclusively to John Von Neumann.
And as a font of all wonders, the Internet Archive will serve up a Naval Postgraduate School paper on using handheld calculators and computers for Target Motion Analysis. I think this is a variation on existing programs in the tactical program library, as I was on shore duty in September 1983, and I think I had been introduced to the HP-67/97 and Sharp PC-1500 programs while on sea duty. It's not important, and I suppose I could dig out my service record and check the dates of my schools. I know I did not see either the HP-75 or the HP-71 as part of the tactical program library, possibly because I think the handheld programs were subsumed by a larger Navy computer effort called JOTS, the Joint Operational Tactical System (Jerry O. Tuttle System).
Parenthetically, with regard to the paper using target bearings accurate to a tenth of a degree, I'm skeptical. With an acoustic towed array, I suppose it's possible to resolve bearing to that precision, if the array is long enough; but I think the tactical towed arrays weren't that long and were probably capable of 1 degree of bearing resolution at best. I could be wrong. And the baseline for own-ship onboard high frequency radio direction finding is likewise not capable of bearing resolution to a tenth of a degree. Again, I could be wrong. But I was surprised to see the author using inputs of that precision. The idea behind TMA was to get an area of probability that was practical to search with a helo or other asset, or to place a Harpoon or Tomahawk missile with its own onboard sensor within an area that ensured a high enough probability of acquiring the target.
One thing leads to another in these spelunking expeditions and I found a guy who makes an arduino interface for the TI-74 and TI-95 to replace the cassette recorder interface, which is nearly impossible to find. $30 shipped, so...
Finally, as serendipity would have it, there's a book coming out on "the rise and reign of the pocket calculator," Empire of the Sum. I looking forward to reading it.
Originally posted at Nice Marmot 04:45 Tuesday, 15 August 2023