Too Many Calculators

I don't know how it started, but it did. Somehow I've ended up collecting old scientific (mostly) calculators. I certainly don't do it for the investment - I think it's more about the thought and engineering that went into many of these, especially the early ones. These were made back when calculators were serious and expensive tools, not just something you pick up while waiting in the check-out line. Good design never goes out of style, and a well made tool will always be useful.

In order of decreasing age (there are some pictures still yet to be taken, others are fuzzy, and the 3d stuff is pretty goofy - at least until we get a good VR stand):

	An HP-35 (1973): The first scientific pocket calculator (way cool! Thanks Susan). This is a version 2 model with the raised bump on the "5" key but no red dot. As an added bonus, it has the ROM bugs like e^x (ln 2.02) = 2, which were corrected in most 35's by a recall. (Read more at the HP calculator museum.)

	A TI SR-11 (1973): SR stood for "slide rule!" While far from the power of the HP-35, it was considerably less expensive and featured a square root function (as well as reciprocal and square). (Read more at the Datamath calculator museum.)

	A TI SR-50 (1974): This was TI's answer to the HP-35. At about half the cost of the 35 and a few more functions (note the hyperbolics) it was very successful. Even more interesting, this was one of the first calculators to implement "algebraic logic" (i.e. operator precedence) where 1 + 2 x 3 gives you 7, not 9. (Read more at the Datamath calculator museum.)

	A Corvus 322 (1974): Not a scientific, but an early basic function model (with memory!). Despite their unique styling, Corvus only produced calculators for a few years. What's interesting about this model is how the memory works (hint: you have to hit the "M" key first to perform any memory manipulation).

	An HP-21 (1975): The next iteration of the HP-35. It was amazing in its day for its small size - you can see it in 3d here (requires Apple's quicktime software). (Read more at the HP calculator museum.)

	A Kings Point SC-20 (197?): OK, I have no idea when this calculator was made and there's very little information about King's Point out there (they didn't last long). I had an SC-20 in junior high school, so that would put it somewhere around here on the list. Unfortunately, this isn't the same machine - my first one was a casualty of my curiosity, and it took me another quarter century (sigh) to find another. Looking inside, it's probably easy to see why King's Point went out of business - the whole thing is hand soldered! It must have taken hours to put together. But it has a good solid feel, a nice keyboard, and is a pleasant machine to work with.

	A Kings Point SC-40 (197?): Like the SC-20, I have little information on this one (even the owner's manual doesn't have a date). It's similar to the SC-20, but despite the larger model number it's missing a few functions compared to the SC-20 (like factorials). On the other hand it seems to be a later manufacture (more integration on the cpu board) and sports a 10 digit display (+2) versus the 8(+2) of the SC-20. I need to get in there and change out the nicads, so I'll try and get a date off the chips too.

	A Radio Shack EC-4001 (1977): Before you laugh, I should point out that it's a re-branded Sinclar Cambridge Programmable - well known for being one of the least accurate calculators ever made. And I don't mean the occasional error - the algorithms it uses are just fundamentally bad (cos(Pi/3) = 0.5002651!). Never trust it to more than 4 digits. But still, it's cool, and was amazingly small and powerful for 1977.

	An HP-67 (1977): I can remember playing with one of these in a store when they first came out and thinking it was one of the most remarkable devices I had ever held. 224 program steps, 26 storage registers (26! that's more than anyone would ever need), and the ability to read/write everything to magnetic cards. Remember, this was back before CMOS memory was widely used, and everyone's calculators forgot your work when you turned them off. They were about $500 back then, so there was no way a 14 year old kid was ever going to get one, and sure enough, it took me another 25 years. You can see it in 3d here (requires Apple's quicktime software). (Read more at the HP calculator museum.)

	An HP-97 (1978): This is the desktop version of the HP-67 (just above). Although it is portable (including rechargable batteries) it's a bit much to put in your pocket - or backpack for that matter!. (Read more at the HP calculator museum.)

	A Radio Shack EC-4000 Programmable Calculator (1978). This is really a re-branded TI-57 (only the label is different). Produced from 1977 to 1982, the 57 was the low end of the 57/58/59 series (8 memories and 50 merged program steps). (Read more at the Datamath calculator museum.)

	A Sharp EL-5100 (1979): Simply a classic. When people talk about extraordinary design, this is it! I actually bought this one for myself when I was in high school. At the time, I didn't have the money for an HP and I preferred the Sharp design/features to the Ti's (that still holds true today).

	A Sharp EL-208 (1979): Not really a scientific, but there's something cute about an LCD calc that needs a 9V battery! It's tiny and oddly shaped to boot.

	A TI-55 (1979): What can I say. It's the mini-van of the late 1970's calcs. Well, that and the Ti-30 (the 30 was the 4 cylinder mini-van, the 55 was the V-6). (Learn more about it at the Datamath museum.)

	A Radio Shack TRS-80 Pocket Computer (PC-1) (1980?): One of the first pocket computers (programs in BASIC), it's really a Sharp PC-1211 with the Radio Shack label on it (all their calculators and pocket computers were made by 3rd parties). It can store about 1400 steps and 26 memories and can even be interfaced with a cassette tape recorder for storage of programs/data. Internally it's even more interesting with 2 4-bit CPUs, one for the display and one for the BASIC interpreter.

	A Sharp EL-512 (date unknown): Little and pretty beat up. I'm not even sure how I ended up with this one (I remember it from college, I think). Still, a lot of power in a small package - it's even programmable in a limited"recording keystrokes" mode.

	An HP-33C (1980): This was the bottom line of the "Spice" series programmable scientifics. It's interesting to compare this to an HP-32C (which I don't have) - notice the functions that were removed in order to provide program registers (what! no hyperbolics?). (Read more at the HP calculator museum.)

	An HP-34C (1981): The top of HP's "Spice" series, this one features built in numerical integration and equation solving. 20 years ago!!! And the numbers flash while it's thinking, which you really can't beat. You can see it in 3d here (requires Apple's quicktime software). (Read more at the HP calculator museum.)

	An HP-41C (1981): This was the first of the HP hand calculators to use an LCD display rather than an LED. Even more remarkable was its alphanumeric capabilities - calculators had pretty much reached the point where they had more functions than could be assigned to keys (note the 34C above, which has 4 functions per key!). For the HP-41C, there were about twice as many functions in ROM than you could get at from the keyboard. These functions are called by putting the calculator into "alpha" mode and typing in the name (later calculators started using menus, like the 28C below). The calculator itself is remarkably expandable (4 expansion ports) and clearly one of the most significant calculator of the early 1980's. You can see it in 3d here (requires Apple's quicktime software). (Read more at the HP calculator museum.)

	A TI-58C (1981): They made me buy this for college calculus. While it didn't have "lots" of built in functions, it had a lot of memory - program steps and register storage. You could also get little "solid state modules" that plugged into the back and added functions (programs). A good work horse, but it never quite impressed me as being as "interesting" as the HP and Sharp models of the time. (Read more at the DataMath Calculator Museum.)

	An HP-71B (1984): This was one of HP's forays into the world of handheld "computers" that were programmable in BASIC. But unlike the 75C/D, the 71B had a separate numerical keyboard and a very interesting "CALC" mode with an oddly logical operator precedence input mode (it is not an RPN calculator). With about 17Kb RAM, 4 expansion slots, an optional magnetic card reader and HP-IL interface, this was a very powerful device (many saw service as portable data collection/control systems). (Read more at the HP calculator museum.)

	An HP-11C (1985): The HP 10 through 16 series is an interesting contrast to the HP-41C/CV/CX - more of a replacement for the 30 series and a traditional calculator (and at $130, a lot cheaper). Despite its small size, it's a remarkably capable machine and a favorite (along with the 10, 15, and 16) among collectors. (Read more at the HP calculator museum.)

	A Sharp EL-5150 (1986): The rare updated version of the 5100. This is tied with the HP-34c and HP-67 as my favorites, although the way you enter equations is considerably different from most calculators. Many functions are entered more like you would read/write them, like <ln> <2> = to find the the natural log of 2, which takes a lot of getting used to (especially after having used RPN for a while).

	An HP-28C (1987): I bought this for myself as a present for passing my Ph.D. qualifying exam. This was one of the first calculators capable of doing symbolic math - including calculus! But the 28C was somewhat limited by it's small about of memory. I never really liked the on-screen menus though either - I want buttons, lots and lots of buttons. The 28C (and it's financial model cousin) were also HP's first calculators to use the clamshell case. It turned out to be unpopular because it made using the calculator while holding it very difficult. (Read more at the HP calculator museum.)

	A Sharp EL-5500II (1987?): Hmmm. Programs in Basic plus has a regular calculator mode which is quite powerful. This is a fun one!

	A Sharp EL-5500III (198?): This is the last of the EL-5500 series of calculator/computers. It has twice the RAM and a much larger ROM (almost double) compared to the 5500II.

	An HP-48G (1996): OK, this one shouldn't be here, but it is interesting to compare this with the HP-35 above just to show how far things progressed in the 23 year between them. But even for its power, the 48 is a tough machine to use - almost too many functions, many lost deep in menus within menus!