An Emulator For OBP, The Spaceflight Computer From The 1960s

November 1, 2021 by Donald Papp 9 Comments

[David Given] frequently dives into retrocomputing, and we don’t just mean he refurbishes old computers. We mean things like creating a simulator and assembler for the OBP spaceflight computer, which was used in the OAO-3 Copernicus space telescope, pictured above. Far from being a niche and forgotten piece of technology, the On-Board Processor (OBP) was used in several spacecraft and succeeded by the Advanced On-board Processor (AOP), which in turn led to the NASA Standard Spaceflight Computer (NSSC-1), used in the Hubble Space Telescope. The OBP was also created entirely from NOR gates, which is pretty neat.

One thing [David] learned in the process is that while this vintage piece of design has its idiosyncrasies, in general, the architecture has many useful features and is pleasant to work with. It is a bit slow, however. It runs at a mere 250 kHz and many instructions take several cycles to complete.

Sample of the natural-language-looking programming syntax for the assembler. (Example from page 68 of the instruction set manual for the OBP.)

One curious thing about the original assembler was documentation showing it was intended to be programmed in a natural-language-looking syntax, of which an example is shown here. To process this, the assembler simply mapped key phrases to specific assembly instructions. As [David] points out, this is an idea that seems to come and go (and indeed the OBP’s successor AOP makes no mention whatsoever of it, so clearly it “went”.) Since a programmer must adhere to a very rigid syntax and structure anyway to make anything work, one might as well just skip dealing with it and write assembly instructions directly, which at least have the benefit of being utterly unambiguous.

We’re not sure who’s up to this level of detail, but embedded below is a video of [David] coding the assembler and OBP emulator, just in case anyone has both an insatiable vintage thirst and a spare eight-and-a-half hours. If you’d prefer just the files, check out the project’s GitHub repository.

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A conventiongoer plays Pokemon on a working Color Game Boy costume.

Convention Plays Pokemon On Giant Color Game Boy Costume

September 29, 2021 by Kristina Panos 2 Comments

Standard cosplay is fun and all, but what is there for admirers to do but look you up and down and nitpick the details? Interactive cosplay, now that’s where it’s at. [Jaryd Giesen] knows this, and managed to pull together a working color Game Boy costume in a few days.

The original plan was to use a small projector on an arm, like one of those worm lights that helped you see the screen, but [Jaryd] ended up getting a secondhand monitor and strapping it to his chest. Then he took the rest of the build from there. Things are pretty simple underneath all that cardboard: there’s a Raspberry Pi running the RetroPie emulator, a Pico to handle the inputs, and two batteries — one beefy 12,000 mAH battery for the monitor, and a regular power pack for the Pi and the Pico.

As you’ll see in the build and demo video after the break, nearly 100 people stopped to push [Jaryd]’s buttons. They didn’t get very far in the game, but it sure looks like they had fun trying.

Since we’re still in a pandemic, you may want to consider incorporating a mask into your Halloween costume this year. Just a thought.

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Interactive Clips For Game Boy: Sit Back And Watch Or Take Control

September 21, 2021 by Kristina Panos 4 Comments

How often does this happen to you? You find yourself describing something that happened in a game to someone, and they’re not sure they know what part of the map you’re talking about, or they’ve never gotten that far. Wouldn’t it be cool to make a bookmark in a video game so you can jump right to the beginning of the action and show your friend what you mean using the actual game?

That’s the idea behind [Joël Franusic] and [Adam Smith]’s fantastic Playable Quotes for Game Boy — clip-making that creates a 4-D nugget of gameplay that can either be viewed as a video, or played live within the bounds of the clip. The system is built on a modified version of the PyBoy emulator.

Left: the full game ROM. Right: a bookmarked slice of the game ROM with the rest set to zero.

Basically, a Playable Quote is made up of a save state and all that entails, plus a slice of the game’s ROM that includes just enough game data to recreate an interactive clip. Everything is zipped up and steganographically encoded into a PNG file. Here’s a Tetris quote you can play (or watch) right now — you might recognize it from the post thumbnail. You’ll find the others on the games site, which allows people to create and share and build on each other’s work.

There’s so much more that can be done with this type of immersive and interactive tool outside the realm of games, and we’re excited to see where this leads and what people do with it.

Haven’t heard of PyBoy before? Let us introduce you.

Hey, MiSTer Emulator, Gimme Almost Any Classic Platform!

September 12, 2021 by Jenny List 20 Comments

I’m back with another of the talks from Hackerspace Gent’s NewLine conference, fresh from my weekend of indulgence quaffing fine Belgian food and beers while mixing with that country’s hacker community. This time it’s an overview from [Michael Smith] of the MiSTer project, a multi-emulator using an FPGA to swap out implementations of everything from an early PDP minicomputer to an 80486SX PC.

At its heart is a dev board containing an Intel Cyclone SoC/FPGA, to which a USB hub must be added, and then a memory upgrade to run all but the simplest of cores. Once the hardware has been taken care of it almost seems as though there are no classic platforms for which there isn’t a core, as a quick browse of the MiSTer forum attests. We are treated to seamless switching between SNES and NED platforms, and even switching different SID chip versions during a running Commodore 64 demo.

There are many different routes to a decent emulator set-up be they using hardware, software, or a combination of both. It’s unlikely that there are any as versatile as this one though, and we’re guessing that as it further evolves it will become a fixture below the monitor or TV of any gamer. It’s a step up from single-platform FPGA emulators, that’s for certain!

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GateBoy Is A Game Boy Emulated At Gate Level

September 7, 2021 by Lewin Day 26 Comments

Old game systems are typically the most popular targets for emulation. With huge communities of fans wanting to recreate the good times of yesteryear, most old systems have all been brought back to life in this manner. However, some simply dive into emulation for the technical challenge, and [Austin Appleby] has done just that with GateBoy.

GateBoy is a project to emulate the Game Boy logic gate by logic gate. It’s a lower level approach that builds upon earlier work [Austin] did on a project called MetroBoy, which we featured previously.

The emulator was created by painstakingly reverse-engineering the logic of the Game Boy. This was done by poring over die shots of the actual DMG-01 CPU silicon. GateBoy emulates most of the chip, though avoids the audio hardware at this stage.

Presently, GateBoy runs at roughly 6-8 frames per second on a modern 4GHz CPU. As it turns out, emulating all those gates and the various clock phases at play in the DMG-01 takes plenty of processing power. However, compilation optimizations do a lot of heavy lifting, so in some regards, GateBoy runs impressively quickly for what it is.

[Austin] still has plenty of work to do before GateBoy is completely operational, and there are some strange quirks of the Game Boy hardware that still need to be figured out. Regardless, it’s a fantastic academic exercise and a noble effort indeed. Meanwhile, you might like to check out the Game Boy emulator that runs just one single game.

Pi Pico Emulates ROM For Speedy Retro Hacking

September 2, 2021 by Tom Nardi 22 Comments

If you’ve ever worked on a system that loads its software from a ROM or EPROM, you know how much of a hassle it can be to make frequent changes to the code. Pulling the chip, flashing it, and sticking it back into the socket each time you change a line isn’t anyone’s idea of a good time. Which is why [Nick Bild] has come up with the PicoROM, a way to emulate a ROM chip using the Raspberry Pi Pico.

With the Pi Pico standing in for the original ROM, updating firmware takes a fraction of the time and doesn’t require you to actually disconnect any of the hardware. [Nick] had done something similar with FPGAs in the past, but the far cheaper and easier to work with Pi Pico makes this version particularly appealing. The secret to getting it to work is the overclocking potential of the Pico, which he says has been pushed to 400 MHz for this particular application.

The downside is that you can’t access the Pico’s onboard flash when the chip is running that fast. To get around that limitation, all of the code is loaded into the microcontroller’s RAM. With a healthy 264 KB of memory this isn’t really a problem when emulating 32 KB chips, but [Nick] says his method would quickly fall apart for larger ROMs.

Beyond the Pi Pico itself, [Nick] is using a trio of 74LVC245AN 8-bit logic level shifters so the chip can talk to the 5 V logic of his homebrew 6502 computer. With everything wired up on a simple breadboard, PicoROM has no trouble serving up the operating system as it hums along at 2 MHz.

Of course, a modern high-performance microcontroller isn’t strictly necessary. In the past we’ve covered devices that could emulate an EPROM using 1990s era silicon.

Calculate Like It’s 1989 With This HP15C Emulator

August 31, 2021 by Dan Maloney 41 Comments

Back in the day, your choice of calculator said a lot about your chops, and nothing made a stronger statement than the legendary Hewlett-Packard Voyager series of programmable calculators. From the landscape layout to the cryptic keycaps to the Reverse Polish Notation, everything about these calculators spoke to a seriousness of purpose.

Sadly, these calculators are hard to come by at any price these days. So if you covet their unique look and feel, your best bet might be to do like [alxgarza] and build your own Voyager-series emulator. This particular build emulates the HP15C and runs on an ATMega328. Purists may object to the 192×64 LCD matrix display rather than the ten-digit seven-segment display of the original, but we don’t mind the update at all. The PCB that the emulator is built on is just about the right size, and the keyboard is built up from discrete switches that are as satisfyingly clicky as the originals. We also appreciate the use of nothing but through-hole components — it seems suitably retro. The video below shows that the calculator is perfectly usable without a case; a 3D-printed case is available, though, as is an overlay that replicates the keypad of the original.

We’ve seen emulators for other classic calculators of yore, including Sinclair, Texas Instruments, and even other HP lines. But this one has a really nice design that gets us going.

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