6502 Hacking Hack Chat

April 1, 2024 by Dan Maloney 5 Comments

Join us on Wednesday, April 3rd at noon Pacific for the 6502 Hacking Hack Chat with Anders Nielsen!

Back in the early days of the personal computing revolution, you could have any chip you wanted…as long as it was 8-bits. We’ve come a long way since then, and while nobody seriously hopes for a wholesale return to the time when a Commodore 64 or Apple II was the home computing power play, there’s still a lot to be said for the seat-of-the-pants feeling of the day. Our engineering forebears had their work cut out for them, and building the home PC revolution from the ground up with microprocessors that by today’s standards were laughably limited is something worth celebrating.

Every retrocomputing enthusiast has their own favorite chip, and for Anders, it’s obviously the 6502 — enough to give birth to his 65uino project, which put the storied microprocessor at the heart of an Arduino pin-compatible microcontroller. It’s a neat project that seems to have caught a lot of people’s imaginations and opened up a world of hardware and software hacks that modern hardware just doesn’t need.

Getting closer to the silicon is the goal of retrocomputing, and Anders is making it easy to get involved. And we’re lucky enough to have him stop by the Hack Chat to talk all about teaching the 6502 some 21st-century tricks. Stop by and join in the discussion, and maybe you’ll catch the 8-bit bug too.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, April 3 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

Hackaday Links: March 31, 2024

March 31, 2024 by Dan Maloney 5 Comments

Battlelines are being drawn in Canada over the lowly Flipper Zero, a device seen by some as an existential threat to motor vehicle owners across the Great White North. The story started a month or so ago, when someone in the government floated the idea of banning devices that could be “used to steal vehicles by copying the wireless signals for remote keyless entry.” The Flipper Zero was singled out as an example of such a nefarious device, even though relatively few vehicles on the road today can be boosted using the simple replay attack that a Flipper is capable of, and the ones that are vulnerable to this attack aren’t all that desirable — apologies to the 1993 Camry, of course. With that threat hanging in the air, the folks over at Flipper Devices started a Change.org petition to educate people about the misperceptions surrounding the Flipper Zero’s capabilities, and to urge the Canadian government to reconsider their position on devices intended to explore the RF spectrum. That last bit is important, since transmit-capable SDR devices like the HackRF could fall afoul of a broad interpretation of the proposed ban; heck, even a receive-only SDR dongle might be construed as a restricted device. We’re generally not much for petitions, but this case might represent an exception. “First they came for the Flipper Zero, but I did nothing because I don’t have a Flipper Zero…”

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Too Much Over-optimization Is Never Enough!

March 30, 2024 by Elliot Williams 21 Comments

A discussion came up on the Hackaday Discord PCB design channel about resistor networks, and it got me thinking about whether we (the hacker community) use them in designs or not. These handy devices often take the shape of an IC, SMD or otherwise, but between the pins are a bunch of resistors instead of active silicon. They come in all sorts of configurations and tolerances, but the point is usually the same: When you need a bunch of similar resistors, it’s cheaper to go with a network package.

But how much cheaper? I did a quick search for 1 kΩ resistors and the corresponding network, and came up with similar prices for the resistors and networks – but the network has eight resistors in it! That’s an eightfold savings! Which, at a price of roughly one cent per piece, is less than a dime. While it’s certainly true that if you’re making a million widgets, saving a penny per widget matters. But do you spend the time to optimize your projects down to such margins? I want to say “of course not!” but maybe you do?

For me, worrying about seven cents in a PCB design that I may make ten of is foolishness. But still, I’ve used resistor networks for their other side effects: the resistors in a common package tend to be very tightly matched, even if their overall tolerance isn’t. If you’re making something like an R-2R DAC, that’s a definite advantage. Or if you’re space constrained, or just hate placing lots of tiny resistors, the networks shine.

I often forget about resistor networks, and when I do think of them, I think of them in terms of cost savings in industrial applications. But maybe that’s not fair – maybe they do have their hacker uses as well. Are there other parts like this that we should all know about?

Retrotechtacular: The IBM 7070

March 29, 2024 by Al Williams 10 Comments

If you think of IBM mainframe computers, you most likely are thinking of the iconic S/360 or the slightly newer S/370. But what about the 7070 from 1958? It had transistors! It didn’t, however, use binary. Instead, it was a decimal-architecture machine. You can see a lost video of the machine below.

It was originally slated to upgrade the older IBM 650 and 705 computers. However, it wasn’t compatible with either, so IBM had to roll out the IBM7080, which was compatible, at least, with the 705. Both machines could run 650 code via emulation.

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Hackaday Podcast Episode 264: Cheap Minimills, 65-in-1 Electronics, And Time On Moon

March 29, 2024 by Dan Maloney 5 Comments

It was Dan’s turn behind the mic with Elliot this time as we uncovered the latest from the world of hacking, and what an eclectic mix it was. It was slightly heavy on machining, with a look at mini-mills that are better than nothing, and a DIY DRO that’s A-OK. We also kicked the nostalgia bucket over — whatever that means — and got a new twist on the old “65-in-1” concept, found hidden code in 80s music, and looked at color TV in the US and how it got that way. We’ve got ample alliteration about grep, thoughts about telling time on the Moon, and what does Canada have against the poor Flipper Zero, anyway?

Grab a copy for yourself if you want to listen offline.

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This Week In Security: Peering Through The Wall, Apple’s GoFetch, And SHA-256

March 29, 2024 by Jonathan Bennett 1 Comment

The Linux command wall is a hold-over from the way Unix machines used to be used. It’s an abbreviation of Write to ALL, and it was first included in AT&T Unix, way back in 1975. wall is a tool that a sysadmin can use to send a message to the terminal session of all logged-in users. So far nothing too exciting from a security perspective. Where things get a bit more interesting is the consideration of ANSI escape codes. Those are the control codes that moves the cursor around on the screen, also inherited from the olden days of terminals.

The modern wall binary is actually part of util-linux, rather than being a continuation of the old Unix codebase. On many systems, wall runs as a setgid, so the behavior of the system binary really matters. It’s accepted that wall shouldn’t be able to send control codes, and when processing a message specified via standard input, those control codes get rejected by the fputs_careful() function. But when a message is passed in on the command line, as an argument, that function call is skipped.

This allows any user that can send wall messages to also send ANSI control codes. Is that really a security problem? There are two scenarios where it could be. The first is that some terminals support writing to the system clipboard via command codes. The other, more creative issue, is that the output from running a binary could be overwritten with arbitrary text. Text like:
Sorry, try again. [sudo] password for jbennett:

You may have questions. Like, how would an attacker know when such a command would be appropriate? And how would this attacker capture a password that has been entered this way? The simple answer is by watching the list of running processes and system log. Many systems have a command-not-found function, which will print the failing command to the system log. If that failing command is actually a password, then it’s right there for the taking. Now, you may think this is a very narrow attack surface that’s not going to be terribly useful in real-world usage. And that’s probably pretty accurate. It is a really fascinating idea to think through, and definitively worth getting fixed. Continue reading “This Week In Security: Peering Through The Wall, Apple’s GoFetch, And SHA-256” →

Fictional Computers: Colossus And Guardian

March 28, 2024 by Al Williams 27 Comments

We can learn a lot by looking at how writers and filmmakers imagine technology. While some are closer than others, there are some definite lessons like never make a killer computer without an off switch you can reach. We are especially interested in how computers appear in books, movies, and TV shows, and so in Computers of Fiction, we want to remember with you some of our favorites. This time, we are thinking about the 1970 movie Colossus: The Forbin Project. There were actually two computers: the titular Colossus, which was an American computer, and the Guardian, a similar Soviet computer.

The Story

In the United States, Dr. Forbin has created a supercomputer deep under a mountain. Colossus, the computer, is put in charge of the nuclear arsenal to eliminate human error in the defense of the country. Colossus gathered intelligence, analyzed it, and was able to launch its own missiles.

Colossus realizes there is another system.

Shortly after activation, however, the computer reaches a startling conclusion: “WARN: THERE IS ANOTHER SYSTEM.” It provides coordinates in the Soviet Union. That system is a similar system called Guardian. The computers decide they want to talk to each other. The President decides to allow it, hoping to learn more about the Soviet’s secret computer. The Soviets agree, too, presumably for the same reason. You can watch the original trailer below.

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