Making A 286 Think It’s Alive Again

March 1, 2026 by Lewin Day 8 Comments

[Nagy Krisztián] had an Intel 286 CPU, only… There was no motherboard to install it in. Perhaps not wanting the processor to be lonely, [Nagy] built a simulated system to bring the chip back to life.

Okay, 68 pins does look like a lot when you arrange them like that.

The concept is simple enough. [Nagy] merely intended to wire the 286 up to a Raspberry Pi Pico that could emulate other parts of a computer that it would normally expect to talk to. This isn’t so hard with an ancient CPU like the 286, which has just 68 pins compared to the 1000+ pins on modern CPUs. All it took was a PLCC-68 socket, an adapter PCB, a breadboard, and some MCP23s17 logic expanders to give the diminutive microcontroller enough I/O. With a bit of work, [Nagy] was able to get the Pi Pico running the 286, allowing it to execute a simple program that retrieves numbers from “memory” and writes them back in turn.

Notably, this setup won’t run the 286 at its full clock speed of 12 MHz, and it’s a long way off from doing anything complex like talking to peripherals or booting an OS. Still, it’s neat to see the old metal live again, even if it’s just rattling through a few simple machine instructions that don’t mean a whole lot. [Nagy] equates this project to The Matrix; you might also think of it as a brain in a jar. The 286 is not in a real computer; it’s just hooked up to a microcontroller stimulating its various pins in a way that is indistinguishable from its own perspective. Continue reading “Making A 286 Think It’s Alive Again” →

The PC In Your Pico

August 18, 2025 by Jenny List 34 Comments

We’re all used to emulating older computers here, and we’ve seen plenty of projects that take a cheap microcontroller and use it to emulate a classic home computer or gaming platform. They’re fun, but serve mostly as a way to relive old toys.

As microcontrollers become faster though it’s inevitable that the machines they can emulate become more powerful too, so we’re moving into the realm of emulating productivity machines from years past. An example is [Ilya Maslennikov]’s pico-286, which as its name suggests, is a 286 PC emulator for the Raspberry Pi Pico.

It has an impressive set of sound and video card emulations, can drive either a VGA or an HDMI monitor, and uses a PS/2 keyboard and mouse. If DOS games are your thing it should provide what you want, but it’s caught our eye because there was a time when a 286 DOS PC was a productivity machine. There’s a huge library of still-useful software for DOS, and thus the prospect of a handheld DOS PC still has some appeal. We’d love to see someone put this in a badge.

MS-DOS may no longer be for sale, but there are several ways to land an open-source DOS in 2025. FreeDOS is something of a powerhouse.

Comprehensive Test Set Released For The Intel 80286

July 24, 2025 by Lewin Day 23 Comments

Remember the 80286? It was the sequel to the 8086, the chip that started it all, and it powered a great number of machines in the early years of the personal computing revolution. It might not be as relevant today, but regardless, [Daniel Balsom] has now released a comprehensive test suite for the ancient chip. (via The Register)

The complete battery of tests are available on Github, and were produced using a Harris N80C286-12 from 1986. “The real mode test suite contains 326 instruction forms, containing nearly 1.5 million instruction executions with over 32 million cycle states captured,” Daniel explains. “This is fewer tests than the previous 8088 test suite, but test coverage is better overall due to improved instruction generation methods.” For now, the tests focus on the 286 running in real mode. There are no “unreal” or protected mode tests, but [Daniel] aims to deliver the in the future.

[Daniel] uses the tests with the ArduinoX86, a platform that uses the microcontroller to control and test old-school CPUs. The tests aid with development of emulators like [Daniel’s] own MartyPC, by verifying the CPU’s behavior in a cycle-accurate way.

We’ve explored some secrets of the 286 before, too. If you’ve been doing your own digging into Intel’s old processors, or anyone else’s for that matter, don’t hesitate to notify the tipsline.

[Thanks to Stephen Walters for the tip!]

Making Intel Mad, Retrocomputing Edition

June 9, 2024 by Bryan Cockfield 20 Comments

Intel has had a deathgrip on the PC world since the standardization around the software and hardware available on IBM boxes in the 90s. And if you think you’re free of them because you have an AMD chip, that’s just Intel’s instruction set with a different badge on the silicon. At least AMD licenses it, though — in the 80s there was another game in town that didn’t exactly ask for permission before implementing, and improving upon, the Intel chips available at the time.

The NEC V20 CPU was a chip that was a drop-in replacement for the Intel 8088 and made some performance improvements to it as well. Even though the 186 and 286 were available at the time of its release, this was an era before planned obsolescence as a business model was king so there were plenty of 8088 systems still working and relevant that could take advantage of this upgrade. In fact, the V20 was able to implement some of the improved instructions from these more modern chips. And this wasn’t an expensive upgrade either, with kits starting around $16 at the time which is about $50 today, adjusting for inflation.

This deep dive into the V20 isn’t limited to a history lesson and technological discussion, though. There’s also a project based on Arduino which makes use of the 8088 with some upgrades to support the NEC V20 and a test suite for a V20 emulator as well.

If you had an original IBM with one of these chips, though, things weren’t all smooth sailing for this straightforward upgrade at the time. A years-long legal battle ensued over the contents of the V20 microcode and whether or not it constituted copyright infringement. Intel was able to drag the process out long enough that by the time the lawsuit settled, the chips were relatively obsolete, leaving the NEC V20 to sit firmly in retrocomputing (and legal) history.

Raspberry Pi Does Its Best Retro PC Impression

December 28, 2023 by Tom Nardi 12 Comments

The Raspberry Pi is a popular choice if you’re looking to put together a simple emulation box — it’s relatively cheap, small enough to tuck into pretty much any entertainment center, and benefits from a large and vibrant development community. You can even get enclosures that will dress the Linux single-board computer up like a miniature version of your favorite retro console. But what about the old school PC gamers who want to relive their glory days in a palm-sized package?

Well, if you’ve got a 3D printer, [fantasticmrdavid] might have just the solution for you. This second iteration of his printable Raspberry Pi enclosure is designed to look like the 286 desktop that he had in his youth, complete with a functional “floppy drive” in the front that takes an SD card. With a 3.5 inch MPI3508 LCD up in the “monitor” and a copy of DOSBox on the SD card, you’re well on your way to booting up a copy of Windows 3.11 or building some contraptions in The Incredible Machine.

While the external aesthetics of the design are impeccable, we appreciate that [fantasticmrdavid] didn’t skimp on the internals. There’s mount points for dual 25 mm fans to keep the more powerful variants of the Raspberry Pi cool, and a speaker expansion board that plugs into the GPIO header to provide era-appropriate bloops and bleeps. The tiny details here really shine, like the fact that the face plates for the dual drives are designed as separate pieces so they can be printed in a different color than the main case.

If you’re not interested in the classics, don’t worry. We’ve seen the Raspberry Pi stand in foraa modern gaming PC, complete with the RGB LEDs you’d expect in a contemporary rig.

The 286 Gives Up One Of Its Final Secrets

August 13, 2022 by Jenny List 115 Comments

Though it is largely forgotten today, the Intel 80286 was for a while in the 1980s the processor of choice and designated successor to the 8086 in the world of PCs. It brought a new mode that could address up to 16 Mb of memory, and a welcome speed boost over machines using an 8086 or 8088. As with many microprocessors, it has a few undocumented features, and it’s a couple of these that [rep lodsb] takes a look at. Along the way we learn a bit about the 286, and about why Intel had some of these undocumented instructions in the first place.

If you used a 286 it was probably as an end-user sitting in front of a PC-AT or clone. During manufacture and testing though, the processor had need of some extra functions, both for testing the chip itself and for debugging designs using it. It’s in these fields that the undocumented instructions sit, and they relate to an in-circuit emulator, a 286 with a debug port on some of its unused pins, which would have sat on a plug-in daughterboard for systems under test. The 286 was famous for its fancy extended mode taking rather a long time to switch to, and these instructions relate to loading and saving states before and after the switch.

The 286s time as the new hotness was soon blasted away by the 386 with its support for virtual memory, so for most of us it remains as simply a faster way that we ran 8086 code for a few years. They appear from time to time here, even being connected to the internet.

286 image: Thomas Nguyen (PttNguyen.net), CC BY-SA 4.0.

Compaq 286 Laptop Gets Raspberry Transfusion

April 2, 2022 by Tom Nardi 27 Comments

We know, we know. A lot of you don’t like projects that consist of gutting a vintage computer (or anything else, for that matter) and replacing its internals with modern electronics. But can you really look at the clunky Compaq LTE 286 laptop that [Dmitry Brant] hacked a Raspberry Pi into and honestly say it’s a machine worthy of historical preservation? The 30+ year old laptop had all the design cues of a saltine cracker, and the performance to match. At least now with a Pi under the hood, you can play some newer games on the thing.

Besides, [Dmitry] says the machine was damaged beyond the point of economical repair anyway. The only stock hardware that’s left beyond the case itself is the keyboard, which he was able to get talking USB thanks to a Teensy microcontroller. It’s not immediately clear if any attempt has been made to get the switches above the keyboard working, but we imagine it wouldn’t be too hard to tie them into some spare GPIO pins on the MCU for a bit of added authenticity.

The bottom half of the machine was cleared out to the point of it literally being a husk of its former self, which gave him plenty of room to hold the Pi 3B and the HDMI driver board that controls the new 9-inch TFT display. Speaking of which, the new panel was a close enough match to the original’s aspect ratio that only minor bezel modifications were required to get it to fit. The modern LCD makes for a massive improvement over the original, without looking too conspicuous.

While there’s still plenty of available space inside the Compaq, [Dmitry] has opted not to include an onboard battery at this time. Instead, power is provided to the Pi and associated hardware through a bulkhead mount USB connector on the side of the machine. It looks like it wouldn’t be too much trouble to add support for an off-the-shelf USB battery bank, as we recently saw with a particularly well engineered retro-futuristic folding cyberdeck, but far from us to tell a hacker what they should do with their bespoke computer.