Slicing And Dicing The Bits: CPU Design The Old Fashioned Way

April 22, 2024 by Al Williams 12 Comments

Writing for Hackaday can be somewhat hazardous. Sure, we don’t often have to hide from angry spies or corporate thugs. But we do often write about something and then want to buy it. Expensive? Hard to find? Not needed? Doesn’t really matter. My latest experience with this effect was due to a recent article I wrote about the AM2900 bitslice family of chips. Many vintage computers and video games have them inside, and, as I explained before, they are like a building block you use to build a CPU with the capabilities you need. I had read about these back in the 1970s but never had a chance to work with them.

As I was writing, I wondered if there was anything left for sale with these chips. Turns out you can still get the chips — most of them — pretty readily. But I also found an eBay listing for an AM2900 “learning and evaluation kit.” How many people would want such a thing? Apparently enough that I had to bid a fair bit of coin to take possession of it, but I did. The board looked like it was probably never used. It had the warranty card and all the paperwork. It looked in pristine condition. Powering it up, it seemed to work well.

What Is It?

The board hardly looks at least 40 years old.

The board is a bit larger than a letter-sized sheet of paper. Along the top, there are three banks of four LEDs. The bottom edge has three banks of switches. One bank has three switches, and the other two each have four switches. Two more switches control the board’s operation, and two momentary pushbutton switches.

The heart of the device, though, is the AM2901, a 4-bit “slice.” It isn’t quite a CPU but more just the ALU for a CPU. There’s also an AM2909, which controls the microcode memory. In addition, there’s a small amount of memory spread out over several chips.

A real computer would probably have many slices that work together. It would also have a lot more microprogram memory and then more memory to store the actual program. Microcode is a very simple program that knows how to execute instructions for the CPU. Continue reading “Slicing And Dicing The Bits: CPU Design The Old Fashioned Way” →

The Hunt For MH370 Goes On With Barnacles As A Lead

April 22, 2024 by Lewin Day 43 Comments

On March 8, 2014, Malaysia Airlines Flight 370 vanished. The crash site was never found, nor was the plane. It remains one of the most perplexing aviation mysteries in history. In the years since the crash, investigators have looked into everything from ocean currents to obscure radio phenomena to try and locate the plane. All have thus far failed to find the wreckage.

It was on July 2015 when a flaperon from the aircraft washed up on Réunion Island. It was the first piece of wreckage found, and it was hoped it could provide clues to the airliner’s final resting place. While it’s yet to reveal a final answer as to the aircraft’s fate, some of the ocean life living on it could help investigators need to find the plane. The picture is murky right now, but in an investigation where details are scarce, every little clue helps.

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Hackaday Links: April 21, 2024

April 21, 2024 by Dan Maloney 12 Comments

Do humanoid robots dream of electric retirement? Who knows, but maybe we can ask Boston Dynamics’ Atlas HD, which was officially retired this week. The humanoid robot, notable for its warehouse Parkour and sweet dance moves, never went into production, at least not as far as we know. Atlas always seemed like it was intended to be an R&D platform, to see what was possible for a humanoid robot, and in that way it had a heck of a career. But it’s probably a good thing that fleets of Atlas robots aren’t wandering around shop floors or serving drinks, especially given the number of hydraulic blowouts the robot suffered. That also seems to be one of the lessons Boston Dynamics learned, since Atlas’ younger, nimbler replacement is said to be all-electric. From the thumbnail, the new kid already seems pretty scarred and battered, so here’s hoping we get to see some all-electric robot fails soon.

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A standard-compliant MXM card installed into a laptop, without heatsink

MXM: Powerful, Misused, Hackable

April 18, 2024 by Arya Voronova 28 Comments

Today, we’ll look into yet another standard in the embedded space: MXM. It stands for “Mobile PCI Express Module”, and is basically intended as a GPU interface for laptops with PCIe, but there’s way more to it – it can work for any high-power high-throughput PCIe device, with a fair few DisplayPort links if you need them!

You will see MXM sockets in older generations of laptops, barebones desktop PCs, servers, and even automotive computers – certain generations of Tesla cars used to ship with MXM-socketed Nvidia GPUs! Given that GPUs are in vogue today, it pays to know how you can get one in low-profile form-factor and avoid putting a giant desktop GPU inside your device.

I only had a passing knowledge of the MXM standard until a bit ago, but my friend, [WifiCable], has been playing with it for a fair bit now. On a long Discord call, she guided me through all the cool things we should know about the MXM standard, its history, compatibility woes, and hackability potential. I’ve summed all of it up into this article – let’s take a look!

This article has been written based on info that [WifiCable] has given me, and, it’s also certainly not the last one where I interview a hacker and condense their knowledge into a writeup. If you are interested, let’s chat!

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VCF East 2024 Was Bigger And Better Than Ever

April 17, 2024 by Tom Nardi 16 Comments

I knew something had changed before I even paid for my ticket to this year’s Vintage Computer Festival East at the InfoAge Science and History Museum in Wall, New Jersey.

Over the last couple of years, attendance has been growing to the point that parking in the lot directly next to the main entrance has been reserved for only the earliest of risers. That hasn’t described yours truly since the days when I still had what my wife refers to as a “real job”, so that’s meant parking in the overflow lot down the road and walking the half a mile or so back to the main gate. Penance for working on the Internet, let’s call it.

But this time, while walking along the fence that surrounds the sprawling InfoAge campus, I came across an open gate and a volunteer selling tickets. When commenting to her that this was a pleasant surprise compared to the march I’d anticipated, she responded that there had been so many people trying to get into the main entrance that morning that they decided to station her out here to handle the overflow.

I was a few steps past her table and into InfoAge before the implications of this interaction really hit me. Two entrances. How many attendees does there need to be before you setup a secondary ticket booth out by the reserve parking lot just to keep things moving smoothly? Well, I can’t tell you what the exact number is. But after spending the rest of the day walking between all the buildings it took to contain all of the exhibits, talks, and activities this year, I can tell you it’s however many people came to VCF East 2024.

Compared to its relatively humble beginnings, it’s incredible to see what this event has grown into. InfoAge was packed to the rafters, and despite what you might think about a festival celebrating decades old computing hardware, there were plenty of young faces in the crowd. I’m not sure exactly what’s changed, but the whole place was positively jumping. Perhaps it’s partially the generational nostalgia that’s kept Netflix cranking out new seasons of the 1980’s set Stranger Things. I’m sure attention (and attendance) from several well known YouTube personalities have played a big part as well.

Whatever the magic formula that’s turned what was once a somewhat somber retrospective on early desktop computers into a major destination for tech lovers, I’m all for it. Love Live the Vintage Computer Festival!

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Microsoft Killed My Favorite Keyboard, And I’m Mad About It

April 16, 2024 by Lewin Day 74 Comments

As a professional writer, I rack up thousands of words a day. Too many in fact, to the point where it hurts my brain. To ease this burden, I choose my tools carefully to minimize obstructions as the words pour from my mind, spilling through my fingers on their way to the screen.

That’s a long-winded way of saying I’m pretty persnickety about my keyboard. Now, I’ve found out my favorite model has been discontinued, and I’ll never again know the pleasure of typing on its delicate keys. And I’m mad about it. Real mad. Because I shouldn’t be in this position to begin with!

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Hackaday Links: April 14, 2024

April 14, 2024 by Dan Maloney 10 Comments

The Great American Eclipse v2.0 has come and gone, sadly without our traveling to the path of totality as planned; family stuff. We did get a report from friends in Texas that it was just as spectacular there as expected, with the bonus of seeing a solar flare off the southwest limb of the disk at totality. Many people reported seeing the same thing, which makes us a bit jealous — OK, a lot jealous. Of course, this presented an opportunity to the “Well, ackchyually” crowd to point out that there were no solar flares or coronal mass ejections at the time, so what people saw wasn’t an exquisitely timed and well-positioned solar flare but rather a well-timed and exquisitely positioned solar prominence. Glad we cleared that up. Either way, people in the path of totality saw the Sun belching out gigatons of plasma while we had to settle for 27% totality.

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