OT--HP & TI in the 70s

Hello all.

Here's a question I've always wondered about. When the SR-52 & 56 were introduced, the comparison charts were arranged to compare the SR-56 to the HP-25 and SR-52 to the HP-65. But, if the 19C, 29C and 67 were available later to parallel the current availability of the SR-52 & 56, wouldn't those be appropriate comparisons instead?

Even though they were released later, the HP-19C/29C would be better comparison to the SR-56 and the HP-67 to the SR-52.

What TI models were released to compare to the 19C/29C and HP-67?

On another note, it seems to me the HP-41 is far superior to both TI-58/58C/59. But, why and how did TI think that the 58/59 system would far exceed the 41?

Edited: 4 May 2012, 9:44 p.m.


You're making the assumption that specific TI models were introduced in response to specific HP models, and vice versa. Except in rare instances, this almost certainly was not true.

What TI models were released to compare to the 19C/29C and HP-67?

The TI-59 and PC-100A were introduced in May 1977, and were generally considered to compete with the HP-67 and HP-97. The HP-29C and HP-19C were introduced in July and September 1977, and perhaps one could consider the TI-58, without or with the PC-100A, to compete with them.

While HP and TI were in competition, that product development usually took a year or more, so both companies were constantly developing new and improved calculators. If one company introduced a new model in May 1977, and the other in September 1977, there is basically no chance that the latter product is an intentional, specific response to the former.

But, why and how did TI think that the 58/59 system would far exceed the 41?

Who says that they did? The TI-58 and TI-59 were introduced in May 1977. They had more functionality than the HP-67, which had been introduced in July 1976, but they probably were not so much a response to the HP-67 as an obvious evolution of the SR-52.

The HP-41C wasn't introduced until more than two years later, in July 1979.

The more interesting question is why TI cancelled the TI-88, which would have been somewhat competitive with the HP-41C. Of course, even if they had shipped it, they would have been fairly late to the party, since they didn't even announce it until May 1982. That is clearly a demonstration of the long product development cycle; it is quite possible that they didn't anticipate that HP would introduce something anywhere near as sophisticated as the HP-41C in 1979.


Eric, thanks for your always-enlightening posts. I always find them interesting.


Hello Eric and the group.

For a long time, since (yes, I'll admit it) I was an avid TI user and a dedicated calculator aficionado, During that time, I've noticed the various comparisons between TI & HP calcs . From the TI sales brochures, comparisons in their charts compare various HP models (HP-35, 45, 55, 65 and 25) against the TI equivalents SR-50, SR-51, SR-52 and SR-56 and so forth. Although your references point out the asynchronous release dated between HP & TI models, I guess it was just my impression that TI & HP were in competition with one another. Just my impressions. Thanks for setting the record straight.

Edited: 5 May 2012, 12:24 a.m.


The comparisons were made when the units were available. The developments were independent.

The main drawback of the SR-56 (my first programmable) was the lack of constant memory or external storage. That's why I replaced it later with a TI-59. A comparison between the SR-56 and an HP-25 seems fair.


Back in those days Richard Nelson who was publishing a newsletter for HP users (HP Calculator Journal)and Richard Vanderburgh who was publishing a newsletter for TI users (52 Notes)reached some agreements on matchups for competitive exerecises. Sorry, but I don't have my copies of 52 Notes with me so I can't be sure of what the matchups were or what all the competitive exercises were.

There were some oddities in the competitive results. For example in most cases the TI-59 outperformed the HP-67, but an HP-67 program for finding prime factors couldn't be matched for speed by any TI-59 program. TI-59 programs were better in one respect -- being able to handle 13 digit input integers while the HP-67 programs could only handle 10 digit input integers.


I spent six weeks of my military take-home pay for a new HP-67 and a few accessories in early 1977. Before that I was solidly in the TI camp because of TI's lower cost and better innovation. The SR-56 was my top machine before the HP-67, and I consider it much more capable than the HP-25.

Later in 1977 when TI announced the TI-58 and -59, I bought a 58. I liked it so much that I traded it to a shipyard engineer for his HP-35 (a Red Dot that I still have..though I did not recognize that as significant back then) and bought a TI-59 and PC-100.

Today HP fans often neglect just how much value the PC-100 print cradle added to the the calculator system...much more so than even the innovative Solid State Software modules that the TI-58/59 used. The PC-100 was a wonderful product that also worked with the SR-51, SR-52, and SR-56. It was the first reasonably-priced calculator thermal printer with any degree of sophistication and flexibility. HP had nothing even remotely competitive and versatile until the HP 82240A/B a decade later.

If the TI-59/PC-100 been available when I was first considering the HP-67, I would likely not have purchased the HP-67. The TI system was, except for quality of construction and appearance, much more advanced and capable than my HP-67 at much lower cost. Although it typically took about 35 percent more program steps to program the TI for any application I had on the HP-67, the TI had much more RAM and mag card memory than was wasted by the inefficiency of its algebraic non-stack-based programming model.

However capable the TI system, it failed the test for durability. I've mentioned before that I went through five TI-59s and three PC-100s between 1977 and 1980. During that time, I only had to return the HP-67 for repair once. As a result, all my critical naval nuclear submarine propulsion reactor programming utilized my HP-67 or the HP-97 that I had the ship purchase. However, the old SR-52/PC-100 that I had the ship purchase (in 1976 before either the HP-67 or TI-58/59 had been announced) for the ship's chemistry and radiological lab functioned for years without any problem. I believe that the SR-52 was better built than the TI-58/59.

Of course, the 1977 TI-58/59 and PC-100 were never intended as a competing product line with the HP-41C series that first showed up two and a half years later. To compare these two product lines in such a light is anachronistic nonsense.


Hmm...SR-51/51A latched to the PC-100. I'm guessing, since there were no PRINT functions on the SR-51 itself, the PC-100 did all the automation depending on its PRINT/TRACE/ADV^ switches. Right? Please shed some light on how this worked. Thanks.

Edited: 7 May 2012, 4:07 p.m.


Mat, you got it. There were 4 revisions of the PC-100: The original PC-100, then the A, B and C versions. The oldest model only supported The 51/52 (and probably the 50 and 56) calculators, the A is the most versatile which can be switched to accept all calculators from the 51 to the 59. Later models dropped support for the earlier calculators.

The printer is very accurate and fast because it prints a complete line of dots in one go (no moving head). But the driver chips and the print head are delicate parts, tending to burn up.


I don't have a PC-100A here to check, but didn't the switch have to be placed in the middle position, where there was no logo, to accomodate the TI-58/59?

My other recollection is that the A ran quieter and more reliably than the C. And, wasn't the B for use in Europe?


Thanks! I was just going on instinct and following a hunch. Seems I know more about calcs than I give myself credit for.


I had a PC-100A (which later failed) and it worked with my SR-56 and later with the TI-59. I didn't have an SR-52 at the time and my SR-51A was long given away to my sister so I couldn't try them. The printer mechanics didn't change as far as I can tell, it was mostly the board that was updated.

If you find any of these check if they contain an old battery in the charging compartment (charging added by the A model). The problem is that the outgasing has most probably destroyed traces on the board.


The PC-100 did not have a switch position for the TI-58/59, so it only worked for the SR-51/52 and SR-56. (Unofficially it could sometimes be made to work with the TI-58/59 by getting the switch between the two positions, but it wasn't very reliable and didn't charge batteries like the PC-100A.)

The PC-100A added the switch setting for the TI-58/59 and battery charging.

The PC-100B was a cost reduced version that didn't have the switch, nor the ROMs to support the SR-51/52 and SR-56, so it only worked on the TI-58/59.

The PC-100C was a further cost reduction. It was replaced the PC-100B fairly quickly, so the PC-100B is fairly rare.

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