A Miniature VT102 Running A Miniature PDP11

We spend a lot of time looking at retrocomputing in the form of gaming and home computers, but it’s true to say that minicomputers are less common than hardware projects. Perhaps it’s the size, cost, or even relative rarity of the original machines, but DEC minicomputers are a bit unusual around here. [Sprite_TM] hasn’t bought us a PDP11 or a VT102 terminal, but he’s done the next best thing in the form of a miniature working VT102 that also conceals a PDE11 emulator. It runs Tetris, which was originally developed on a Russian clone of the PDP11 architecture, and the 2.1BSD operating system.

Powering it all is an ESP32 module, and the PDP11 emulator is the well-known SIMH software. Porting this to the slightly limited environment of the microcontroller required a few compromises, namely the network stack and the configuration interface. In a particularly clever move [Sprite_TM] enabled BSD networking by writing an ESP32 layer that takes network packets via SIMD directly from BSD. It includes its own DHCP client and wireless network configuration tool, allowing an ancient UNIX-derived operating system from the 1970s to connect to the 21st century Internet through an emulator with its network code stripped out.

The case is a masterwork in OpenSCAD, a complete VT102 unit in miniature with a tiny LCD screen that when printed on a resin printer is a remarkable facsimile of the real thing. It doesn’t have a keyboard counterpart, but even with a miniature Bluetooth ‘board it still looks pretty impressive. In the video below the break he boots it into 2.1BSD, and importantly since it is a server operating system, logs into it from his laptop and plays a game of Zork.

[Sprite_TM] has brought us so many impressive projects over the years using the ESP32 and other parts. Maybe you have a favorite, but for us it’s the PocketSprite Game Boy-like tiny handheld console.

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“A Guy In A Jet Pack” Reported Flying Next To Aircraft Near LAX

In case you needed more confirmation that we’re living in the future, a flight on approach to Los Angeles International Airport on Sunday night reported “a guy in a jet pack” flying within about 300 yards of them. A second pilot confirmed the sighting. It’s worth watching the video after the break just to hear the recordings of the conversation between air traffic control and the pilots.

The sighting was reported at about 3,000 feet which is an incredible height for any of the jet packs powerful enough to carry humans we’ve seen. The current state of the art limits jet pack tech to very short flight times and it’s hard to image doing anything more than getting to that altitude and back to the ground safely. Without further evidence it’s impossible to say, which has been an ongoing problem with sightings of unidentified flying objects near airports.

While superheros (or idiots pretending to be superheros) flying at altitude over the skies of LA sounds far fetched, the RC super hero hack we saw nine years ago now comes to mind. At 300 yards, that human-shaped drone might pass for an actual person rather than a dummy. This is of course pure speculation and we don’t want to give the responsible members for the RC aircraft community a bad name. It could have just as easily been trash, balloons, aliens, or Mothra. Or perhaps the pilot was correct and it was “some guy” flying past at 3,000 feet. That’s not impossible.

We anxiously await the results of the FAA’s investigation on this one.

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ESP32 Altair Emulator Gets Split Personality

If you wanted me to demo CP/M running on an emulated Altair 8800, I’d pull out a tiny board from my pocket. You might wonder how I wound up with an Altair 8800 that runs CP/M (even WordStar), that fits in your pocket and cost less than $10. Turns out it’s a story that goes back to 1975.

When the Altair 8800 arrived back in 1975, I wanted one. Badly. I’d been reading about computers but had no hands-on experience. But back then, as far as I was concerned, the $400 price tag might as well have been a million bucks. I was working for no real pay in my family’s store, though in all fairness, adjusted into today’s money that was about $2,000.

I’d love to buy one now, but a real Altair costs even more today than it did back then. They also take up a lot of desk space. Sure, there are replicas and I’ve had a few. I even helped work the kinks out of Vince Briel’s clone which I’ve enjoyed. However, the Briel computer has two problems. First, it takes a little work to drive a serial port (it uses a VGA and a PS/2 keyboard). Second, while it’s smaller than a real Altair, it is still pretty large — a byproduct of its beautiful front panel.

So to quickly show off CP/M to someone, you need to haul out a big box and find a VGA monitor and PS/2 keyboard — both of which are becoming vanishing commodities. I made some modifications to get the serial port working, but it is still a lot to cart around. You could go the software route with a simulator like SIMH or Z80pack, but now instead of finding a VGA monitor and a PS/2 keyboard, you need to find a computer where you can install the software. What I really wanted was a simple and portable device that could boot CP/M.

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Learn PDP-11 Assembly For Fun But Probably No Profit

Learning a new skill is fun, especially one that could land you a new job. We don’t think you’ll find too much demand for PDP-11 assembly language programmers, but if it still interests you, check out [ChibiAkumas’s] video that starts a series on that subject for “absolute beginners.”

The PDP-11 is a venerable computer, but you can still find simulators ranging from SIMH to browser-based virtual devices with front panels. If you want real hardware, there is a PDP-11 on a chip that is still around (or you can score the real chips, sometimes) and there are some nice hardware simulations, too.

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Altair 8800 Again Project

[Dirk] posted a video (you can see below) titled, “Mystery Retro Project Start.” That turned out to be the first of a multipart series on his Altair 8800 Again simulator. The front panel appears to be laser cut and in some future video episodes, we expect to see him simulate the CPU with a Teensy.

There have been plenty of 8800 clones ranging from projects that recreate the original PCBs, to those that just run a Raspberry Pi inside. The middle ground will use an Arduino or some other small CPU to simulate the 8080 CPU.

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Better Simulators With Homemade Potentiometers

Perhaps you’ve played a flight simulator before, using something like a mouse and keyboard. That’s a fine experience, but like any other activity you can get a lot more out of it if you put a little more effort into the experience. Some will upgrade to a joystick for a modest improvement, and others will build incredible accurate cockpit replicas down to the smallest detail. The builders of these “pits” are always looking for ways of improving their setups, and it’s from this world that we find a method of building specialized, inexpensive hall-effect sensors.

A hall-effect sensor is a circuit that outputs a voltage based on the presence of an external magnetic field. These can be used to make compasses, but with a permanent magnet in close proximity can also be used to create a potentiometer-like device at lower cost and with higher precision than a similarly-priced pot. There was a method of building these in the simulator world using the housing of a Bic pen and some strong glue, but [LocNar] has improved on this method as well. He repurposed some bearings and some stock metal tubing in order to fabricate a professional-level sensor at a fraction of the cost.

This build is essentially a solution for anyone needing a potentiometer that’s easier to build, less expensive, has higher precision, and interacts with a digital input in a much more predictable (and programmable) way. Certainly this has applications in the simulator world, but will work for many other applications. If you’ve never thought about the intricacies (and shortcomings) of potentiometers, some other folks have taken a deep dive into that as well.

Thanks to [Keith O] for the tip!

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Hackaday Links: May 19, 2019

Cheap nostalgia, that’s the name of the game. If you can somehow build and ship ‘cheap nostalgia’, you’re going to be raking in the bucks. For the ‘musicians’ in the crowd, the king of cheap nostalgia has something great. Behringer is cloning the Yamaha CS-80. and it was announced at this month’s Superbooth.

The Yamaha CS-80 is the synth in Blade Runner, and since Toto’s Africa is making a comeback on top-40 radio, it’s the instrument of our time. A Wonderful Christmas Time, it seems. Aaaannnyway, yes, there might be a huge and inexpensive version of one of the greatest synthesizers ever made real soon. The cheap 808s and 909s are making their way to stores soon, and the 101 needs a firmware update but you can buy it now. Cheap nostalgia. That’s how you do it.

The PiDP-11/70 is a project we’ve been neglecting for some time, which is an absolute shame. This is a miniature simulation of what is objectively the best-looking minicomputer of all time, the PDP-11/70. This version is smaller, though, and it runs on a Pi with the help of SimH. There are injection molded switches, everything is perfect, and now there are a whole bunch of instructional videos on how to get a PiDP-11/70 up and running. Check it out, you want this kit.

Considering you can put a phone screen in anything, and anyone can make a keyboard, it’s a wonder no one is making real, well-designed palmtop computers anymore. The Vaio P series of PCs would be great with WiFi, Bluetooth, and a slight upgrade in memory and storage. This was [NFM[‘s recent project. This palmtop gets an SSD. The object of modification is a decade-old Sony Vaio CPCP11 palmtop modified with a 256 GB SSD. The Vaio only supports PATA, and the SSD is mSATA, so this is really a project of many weird adapters that also have to be built on flex connectors.

Here’s something for the brain trust in the Hackaday comments. First, take a look at this picture. It’s the inside of a rotary encoder. On the top, you have a Gray code (or what have you) that tracks the absolute position of a shaft. On the bottom, you have some sort of optical detection device with 13 photodiodes (or something) that keeps track of each track in the Gray code. This is then translated to some output, hopefully an I2C bus. What is this device, circled in red? I know what it is — it’s an optical decoder, but that phrase is utterly ungooglable, unmouserable, and undigikeyable. If you were me, what would you use to build your own custom absolute rotary encoder and you only needed the sensor? I technically only need 10 tracks/sensors/resolution of 1024, but really I only need a name.

Lol, someone should apply to Y Combinator and pitch yourself as a B Corp.