8086 Multiply Algorithm Gets Reverse Engineered

The 8086 has been around since 1978, so it’s pretty well understood. As the namesake of the prevalent x86 architecture, it’s often studied by those looking to learn more about microprocessors in general. To this end, [Ken Shirriff] set about reverse engineering the 8086’s multiplication algorithm.

[Ken]’s efforts were achieved by using die photos of the 8086 chip. Taken under a microscope, they can be used to map out the various functional blocks of the microprocessor. The multiplication algorithm can be nutted out by looking at the arithmetic/logic unit, or ALU. However, it’s also important to understand the role that microcode plays, too. Even as far back as 1978, designers were using microcode to simplify the control logic used in microprocessors.

[Ken] breaks down his investigation into manageable chunks, exploring how the chip achieves both 8-bit and 16-bit multiplication in detail. He covers how the numbers make their way through various instructions and registers to come out with the right result in the end.

It’s a fun look at what’s going on at the ground level in a chip that’s been around since before the personal computer revolution. For any budding chip designers, it’s a great academic exercise to follow along at home. If you’ve been doing your own digging deep into CPU architectures, don’t hesitate to drop us a line!

Wooden ITX PC Case Smacks Of Sophistication

Computer cases have come a long way from the ugly beige boxes of the early 2000s. Still, if it was going to sit on his desk, [MXC Builds] wanted something with a little more class. His custom Ironbark ITX PC seems to fit the aesthetic nicely.

The case’s outer shell is ironbark wood cut at 45 degrees and joined for a beautiful waterfall edge (the wood grain seems to flow uninterrupted). The power supply was heavily modified to take a thinner but larger fan, and a new cover and intake grill were 3D printed. As there were no mounting holes on the bottom of the power supply, he printed a bracket with spring clips to hold the PSU securely. Next, he routed a PCI riser cable to the other side of the internal panel so the GPU could mount on the back. He cut custom cables to match up the lengths needed for every run. Finally, rather than placing the power button on the front or top, it was on the side in a custom bracket.

It’s an absolutely gorgeous build that packs some respectable hardware in a tiny space (7.9 L or ~482 in3). The use of 3D printed parts and careful planning results in an incredibly tidy computer that most would proudly display on their desk. It is an open-air case, and if you’re looking for something a little more enclosed, perhaps this mid-century PC might whet your appetite.

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Raspberry Pi Adds Second Laptop Monitor

If you have a cheap laptop and you realize you can’t connect a second monitor to it, what do you do? Well, if you are [Pierre Couy], you grab a Raspberry Pi and put together a virtual screen solution.

Like all good projects, this one started with some goals and requirements:

  • Low latency
  • Redable text
  • At least 10 frames per second
  • Fast catch up if the remote screen falls behind
  • Low-bitrate encoding; no hardware acceleration
  • A DHCP server on the Pi to manage the network
  • Power control for the attached monitor

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Sixteen wires of various colors are attached in pairs to record the electrical activity of split gill fungi (Schizophyllum commune) on a mossy, wooden stick. photo by Irina Petrova Adamatzky

Unconventional Computing Laboratory Grows Its Own Electronics

While some might say we’re living in a cyberpunk future already, one technology that’s conspicuously absent is wetware. The Unconventional Computing Laboratory is working to change that.

Previous work with slime molds has shown useful for spatial and network optimization, but mycelial networks add the feature of electrical spikes similar to those found in neurons, opening up the possibility of digital computing applications. While the work is still in its early stages, the researchers have already shown how to create logic gates with these fantastic fungi.

Long-term, lead researcher [Andrew Adamatzky] says, “We can say I’m planning to make a brain from mushrooms.” That goal is quite awhile away, but using wetware to build low power, self-repairing fungi devices of lower complexity seems like it might not be too far away. We think this might be applicable to environmental sensing applications since biological systems are likely to be sensitive to many of the same contaminants we humans care about.

We’ve seen a other efforts in myceliotronics, including biodegradable PCB substrates and attempts to send sensor signals through a mycelial network.

Via Tom’s Hardware.

PCIe For Hackers: The Diffpair Prelude

PCIe, also known as PCI-Express, is a highly powerful interface. So let’s see what it takes to hack on something that powerful. PCIe is be a bit intimidating at first, however it is reasonably simple to start building PCIe stuff, and the interface is quite resilient for hobbyist-level technology. There will come a time when we want to use a PCIe chip in our designs, or perhaps, make use of the PCIe connection available on a certain Compute Module, and it’s good to make sure that we’re ready for that.

PCIe is everywhere now. Every modern computer has a bunch of PCIe devices performing crucial functions, and even iPhones use PCIe internally to connect the CPU with the flash and WiFi chips. You can get all kinds of PCIe devices: Ethernet controllers, high-throughput WiFi cards, graphics, and all the cheap NVMe drives that gladly provide you with heaps of storage when connected over PCIe. If you’re hacking on a laptop or a single-board computer and you’d like to add a PCIe device, you can get some PCIe from one of the PCIe-carrying sockets, or just tap into an existing PCIe link if there’s no socket to connect to. It’s been two decades since we’ve started getting PCIe devices – now, PCIe is on its 5.0 revision, and it’s clear that it’s here to stay.

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A Thoroughly Modern Serial Terminal

The humble desktop serial terminal may have long disappeared from the world of corporate IT, but there are still plenty of moments when professionals and enthusiasts alike need to hook up to a serial port. Many of us use a serial port on our laptops or other mobile devices, but [Neil Crawforth] has gone one better than that with the VT2040. It’s an old-style serial terminal in a super-handy portable format, and as one might guess from the name, it has an RP2040 microcontroller at its heart.

Attached to the chip is a rather nice keyboard, and an ILI9488 480×320 LCD display. The software is modular, providing a handy set of re-usable libraries for the different functions including a PIO-based serial port. His main application seems to be talking to an ESP8266, but we’re guessing with a MAX232 or other level shifter chip it could drive a more traditional port. Everything can be found in the project’s GitHub repository, allowing anyone to join the fun.

As long-time readers will know, we’ve been partial to a few serial terminals in the past. Particularly beloved is this extremely retro model with vintage dot matrix LEDs.

Floppy-8 Is A Tiny PC In A Floppy Drive

At first sight, Floppy-8 is simply a LattePanda based PC built into the shell of a external vintage floppy drive. Indeed, it’s a very nicely executed LattePanda PC in a floppy, and we’re impressed by it. What turns it from a nifty case mod into something a bit special though, is the way creator [Abraham Haskins] has used floppy-like cartridges in the original floppy slot, as a means of loading software.

The cartridges started out as PCBs in the shape of a floppy with an SD socket on their bottom, and progressed to USB drives on 3D printed cartridges and finally and simplest of all, the same 3D printed cartridges with micro SD cards embedded in their leading edges. All this was necessary to get them thin enough to fit into the existing disk slot — if dimensions weren’t a concern, you could enclose various USB devices into printed cartridges. A script on the computer looks for new card insertion, and runs the appropriate autostart.sh script on the SD card if it finds one. If you don’t need the “disks” to fit into an existing slot, you could print them larger and embed

Beyond the cartridges, the PC itself is assembled on a 3D printed frame inside the case. It’s controlled via Bluetooth, with a pair of knock-off NES controllers for games and an Amazon Fire remote for media. We particularly like the idea of weighting the controllers with ball bearings to give them a little heft.

The LattePanda gives the Raspberry Pi a run for its money in these applications. We particularly liked this portable Macintosh.