Another Kind Of “Bare Metal”: 6502 Computer Powers RPN Calculator

[Mitsuru Yamada] states that one of the goals for this 6502 computer build was to make it strong enough to survive real-world usage. In that regard alone we’d call this a success; the die-cast aluminum enclosures used a little blast from the past and lend a nice retro industrial look to the project. The main chassis of the computer fairly bristles with LEDs and chunky toggle switches for setting the data and address busses. The interior is no less tidy, with the 6502 microprocessor — date code from 1995 — and associated support chips neatly arranged on perf board. The construction method is wire wrapping, in keeping with the old-school look and feel. Even the hand-drawn schematic is a work of art — shades of [Forrest Mims].

As for programming, this machine is as low-level as it gets. Nothing but 6502 machine language here, entered manually with the toggle switches, or via an externally programmed ROM. The machine can only address 1k of memory, a limit which the code to support the RPN calculator add-on [Yamada] also built brushes up against, at 992 bytes. The calculator keypad has a 20-key matrix pad and an eight-digit dot-matrix LED display, and can do the four basic operations on fixed-point binary-coded decimal inputs. The brief video below shows the calculator in action.

We love the look of this build and we’re eager to see more like it. We’ve seen a ton of 6502 builds from discrete chips lately, and while we love those too, it’s nice to see one of the big old DIPs put back in action for a change.

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Retrotechtacular: The $5,000 40 Pound HP Classroom Computer

See if you can talk your local school district into buying a computer that costs about $5,000 and weighs 40 pounds. That was HP’s proposition to schools back in 1968 so really it is more like $35,000 today. The calculator had a CRT display for the RPN stack that you could mirror on a big screen. You could also get a printer or plotter add-on. Pretty hot stuff for the ’60s.

The 1970 videos promoting the HP 9100, posted by the [Computer History Archive Project], shows something we’d think of as a clunky calculator, although by the standards of the day it was a pretty good one with trig functions and a crude programming capability.

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3D-Printer And CNC Make This Russian Calculator Bilingual

Let’s be clear right up front: there are probably more obvious solutions to the problem of using a Russian calculator when you don’t speak Russian than printing new keys and engraving translated markings on them. But easy solutions are boring and generally considered beyond the scope of Hackaday articles, so let’s dive in.

They say that mathematics is the universal language, but that’s only true to an extent. Still, even with our limited non-existent Cyrillic skills, the Russian keyboard on this RPN calculator isn’t that hard to figure out. But as [Amen] points out, in the midst of fevered calculations, one prefers not to mentally translate Χ→П to STO or remember that В↑ is the Enter key. So he printed a set of replacements for the confusing keys from PLA. While pondering how to safely fixture such small parts for the later engraving step, [Amen] hit on a genius solution: move the print bed to the CNC router and fixture everything in one go. The resulting characters are large enough to be legible and deep enough to be filled with air-drying polymer clay for contrast. After sanding and polishing, the calculator looks like it came from the Министерство электронной промышленности that way.

Honestly, we’d love to get a look inside this calculator. The insides of Russian electronics can be fascinating, and we’ve even seen entire forums dedicated to decapping Russian parts. But we understand the desire to keep it intact.

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Vintage Console Becomes The Calculator It Appears To Be

What’s sitting on [Bob Alexander]’s desk in the video below did not start out life as the desktop calculator it appears to be. Turning it into a standalone calculator with features the original designers couldn’t imagine turned out to be an interesting project, and a trip down the retrocomputing rabbit hole.

A little explanation is in order. Sure, with its Nixie display, calculator keypad, and chunky mid-century design, the Wang 360 desktop console looks like a retro calculator. But it’s actually only a dumb terminal for a much, MUCH bigger box, called the Electronic Package, that would fit under a desk. The foot-warming part that was once connected to [Bob]’s console by a thick cable that had been unceremoniously lopped off by a previous owner. [Bob] decided to remedy the situation with modern electronics. The console turned out to have enough room for a custom PCB carrying a PIC32, some level-shifting components, power supply modules that include the high-voltage supply for the Nixies, and a GPS module because Nixies and clocks just go together. The interesting bit is the programming; [Bob] chose to emulate the original Wang methods of doing math, which include multiplication by logarithmic addition. Doing so replicates the original look and feel of the calculator down to the rapid progression of numbers across the Nixies as the logarithms are calculated using the display registers.

We normally frown on vintage gear being given modern guts, but in this case [Bob] hit just the right balance of new and old, And given that the Electronic Packages these consoles were connected to go for $1500 or more on eBay, it was a better choice than letting the console go to scrap. A similarly respectful approach was taken with this TRS80 Model 100 revival.

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Hackaday Podcast Ep 007 – Everything Microcontrollers, Deadly Clock Accuracy, CT X-Rays, Mountains Of E-Waste

Elliot Williams and Mike Szczys look at all that’s happening in hackerdom. This week we dive deep into super-accurate clock chips, SPI and microcontroller trickery, a new (and cheap) part on the microcontroller block, touch-sensitive cloth, and taking a home X-ray to the third dimension. We’re saying our goodbyes to the magnificent A380, looking with skepticism on the V2V tech known as DSRC, and also trying to predict weather with automotive data. And finally, what’s the deal with that growing problem of electronic waste?

Links for all discussed on the show are found below. As always, join in the comments below as we’ll be watching those as we work on next week’s episode!

Direct download (88.7 MB)

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Nonpareil RPN HP-41 Calculator Build

The early HP Reverse Polish Notation calculators have a special place in the hearts of engineers and tinkerers as there are lots of projects involving them. They haven’t been produced in decades, but [Chris Chung] has used some open source code to create DIY hardware version of the HP-41 Reverse Polish Notation (RPN) calculator.

The open source code behind the calculator is the Nonpareil High-Fidelity Calculator Simulator, and [Chris] has used it along with a custom designed readout and PCBs to create a working prototype. The simulator uses the original byte code of the HP-41 so the its behavior is exactly the same as the original calculator.

[Chris] has designed the PCBs so that the buttons and the screen are separate and join together. This neat idea means that he can try out different screens or different button PCBs and mix-and-match to find the combination that works best. He’s also designed a 3D printed case for the calculator. He does prefer using the bare buttons on the board to the 3D printed ones he printed for use with the case.

We love calculators here so there have been a bunch of articles over the years. Check out the documentation that comes along with this open source calculator, or check out this pocket calculator that emulates two other pocket calculators!

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Shmoocon: Advanced Low Power Techniques And A Watch

Real quick question: how do you increase productivity at work? The greatest (highest paid) minds would just say: do agile or scrum or something. What’s scrum? That’s where you gather ’round every morning for a waste of time meeting that kills your every desire to be productive. A while back, [Travis Goodspeed] was stuck in some lesser circle of hell like this and in an effort to be polite by not looking at his phone too much, looked at his watch too much. This led to the creation of the Goodwatch, a new bit of hardware that replaces the guts of a Casio calculator watch with a hex editor, ISM-band radio, MSP430 disassembler, and of course an RPN calculator.

[Travis] has already introduced the GoodWatch to the world. We took a look back in December but haven’t heard anything since. His talk at Shmoocon 2018 put a little more light on how this project came to be.

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