Displays (Was: COSMAC Elf 2000 - TIL311 displays)

I love the TIL-311's. I used them to make a display for a microcode ROM dump fixture for Wang 700-series calculators. Having the latch, decoder, and LED display all in one package made the whole thing a lot easier to build. Plus, the display just look cool. Desktop electronic calculators used just about every kind of display technology there was beginning with the Burroughs (and licensees) Nixie tube. Here I list some of them, and some examples (some of which can be found on the Old Calculator Museum website, http://oldcalculatormuseum.com). Nixie tubes were extremely popular in the early days, beginning with the first electronic calculator (Sumlock/Anita Mk 7 & 8), and lasting into the mid-1970's. The SCM Marchant-I "handheld" electronic calculator used Nixie tubes...the only "portable" electronic calculator that I know of that did this. There were also the unusual Nixie-like displays, where a number of digits worth of Nixies were combined into a single tube (Lago Calc LC-816). Small vector CRT displays were used on some early desktop calculators (like Friden 130/132, Friden 1160-series, SCM Cogito 240SR, Victor 14-32x series, and HP 9100A/B, with a few others) , and were very cool. Canon's early electronic calculators (Canon 130, 161, 130S) used edge-lit plastic panels with grain-of-wheat incandescent lamps to light the plastic panel from the edge. The panels had dots etched into them in the shape of digits to catch the light and project it out as numerals to the user. These were abandoned when Canon switched to Nixie tubes, as the edge-lit panel displays were simply too expensive, and tedious to repair when the lamps burned out. As Nixies started to wane in favor of less-expensive display technologies, lots of manufactures went to Burroughs Panaplex panels, which were less expensive, and easier to interface. Lots of machines (of few of which are Wang 600, Commodore US*1/US*8/US*10, Victor 1800-series, Friden 1203) used these panels. A few machines also used tube-type versions of 7-segment gas-discharge displays, such as the Passport CA-850(clone of APF Mark I), and Sperry-made multi-digit gas-discharge modules (Commodore US*14, Tektronix 31). LEDs came on board on some desktop machines (MITS 1440, HP 9800-series), but ended up really being the display of choice for the new up-and coming handheld machines, until VF, and later, LCD displays usurped them. There weren't all that many desktop calculators that ended up using LED displays. VF-style tube displays also took over in desktop and some handheld machines as the reign of gas-discharge tubes and panels came to an end. There was some interesting VF tubes, most notably, the Japanese Iseden-made Itron tubes that had a unique segment rendition to make digits look more "handwritten". These were first used on Sharp's QT-8D calculator, which was the second (though the first successful) electronic calculator to use a MOS/LSI chipset for all of the calculating logic (with the much earlier Victor 3900 actually claiming the title of first, but there were some major problems with the machine that led to low production figures, and many of the machines being recalled). These displays were different enough to make them engaging. Sharp used them on quite a number of desktop and "handheld" (EL-8, EL-8M) machines. Alas, the days of these displays is pretty much gone. LCD and VF panels have replaced them all in calculators, as well as all kinds of other stuff like kitchen appliances, gas pumps (for a long time gas pumps used really large Beckman gas-discharge displays), instrumentation, copiers, audio equipment, and just about everything else that needs a display. Though not used in any calculator that I'm aware of, the Burroughs "Self-Scan" displays, which were gas-discharge dot-matrix displays that used fancy manufacturing techniques to build the shift register that held the state of the dots into the display elements themselves (essentially a planar version of an old Dekatron tube). Data would be clocked into the display and it automatically shifted as the dots were being shifted in, and when static, no refreshing was required. These were used for in displays for early electronic point-of-sale cash registers that would display information about the item as well as the price. They were also used a lot in some early portable data terminals (with a few lines of perhaps 20 characters each). They were also quite popular in Computer Numerical Control (CNC) controllers for displays showing the status of the machine. They significantly reduced the complexity of making a device with a flexible alphanumeric (or even simple graphic) display. These, too, met their end when VF and later, LCD dot matrix displays replaced them. Displays have always been an interest for me, and dovetails well into my calculator fixation. Rick Bensene