Reverse Engineering The NeXT Computer Keyboard Protocol

January 26, 2022 by 22 Comments

The NeXT computer was introduced in 1988, with the high-end machine finding favor with universities and financial institutions during its short time in the marketplace. [Spencer Nelson] came across a keyboard from one of these machines, and with little experience, set about figuring out how it worked.

The keyboard features a type of DIN connector and speaks a non-ADB protocol to the machine, but [Spencer] wanted to get it speaking USB for use with modern computers. First attempts at using pre-baked software found online to get the keyboard working proved to be unreliable. [Spencer] suspected that the code, designed to read 50 microsecond pulses from the keyboard, was miscalibrated.

Some analysis with an oscilloscope and logic analyzer allowed [Spencer] to figure out the keyboard was communicating with pulses ever 52.74 microseconds, corresponding to a frequency of 18.960 kHz, sending two 9-bit messages at a time. Disassembling the keyboard confirmed these findings – inside was a 455 kHz clock, with the keyboard sending a signal every 24 ticks producing the 18.960 kHz output.

Reworking the initial code found online to work with the actual pulse widths coming from the keyboard got everything humming along nicely. Now, [Spencer] has a nice vintage keyboard with excellent feel that reliably works with modern hardware. We’d call that a win.

If you need more of a fix, be sure to dive into Keebin’ with Kristina, a regular column all about our favorite tactile input devices!

Linux Fu: Bash Strings

January 26, 2022 by 40 Comments

If you are a traditional programmer, using bash for scripting may seem limiting sometimes, but for certain tasks, bash can be very productive. It turns out, some of the limits of bash are really limits of older shells and people code to that to be compatible. Still other perceived issues are because some of the advanced functions in bash are arcane or confusing.

Strings are a good example. You don’t think of bash as a string manipulation language, but it has many powerful ways to handle strings. In fact, it may have too many ways, since the functionality winds up in more than one place. Of course, you can also call out to programs, and sometimes it is just easier to make a call to an awk or Python script to do the heavy lifting.

But let’s stick with bash-isms for handling strings. Obviously, you can put a string in an environment variable and pull it back out. I am going to assume you know how string interpolation and quoting works. In other words, this should make sense:

echo "Your path is $PATH and the current directory is ${PWD}"

The Long and the Short

Suppose you want to know the length of a string. That’s a pretty basic string operation. In bash, you can write ${#var} to find the length of $var:


#/bin/bash
echo -n "Project Name? "
read PNAME
if (( ${#PNAME} > 16 ))
then
   echo Error: Project name longer than 16 characters
else
   echo ${PNAME} it is!
fi

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Major Bug Grants Root For All Major Linux Distributions

January 26, 2022 by 65 Comments

One of the major reasons behind choosing Linux as an operating system is that it’s much more secure than Windows. There are plenty of reasons for this including appropriate user permissions, installing software from trusted sources and, of course, the fact that most software for Linux including the Linux kernel itself is open source which allows anyone to review the code for vulnerabilities. This doesn’t mean that Linux is perfectly secure though, as researchers recently found a major bug found in most major Linux distributions that allows anyone to run code as the root user.

The exploit is a memory corruption vulnerability in Polkit, a framework that handles the privilege level of various system processes. It specifically impacts the program pkexec. With the proof-of-concept exploit (file download warning) in hand, all an attacker needs to do to escalate themselves to root is to compile the program on the computer and run it as the default user. An example is shown by [Jim MacDonald] on Twitter for those not willing to try this on their own machines.

As bad as this sounds, it seems as though all of the major distributions that this impacts have already released updates that patch the issue, including Debian, Ubuntu, Red Hat, Fedora, open SUSE, and Arch. There is also a temporary workaround that removes read/write permission from the pkexec program so it can’t run at all. That being said, it might be best to check that your Linux systems are all up-to-date and that no strangers have been typing random commands into the terminal recently.

Strange Computer Languages: A Hacker’s Field Guide

January 26, 2022 by 50 Comments

Why do we build radios or clocks when you can buy them? Why do we make LEDs blink for no apparent purpose? Why do we try to squeeze one extra frame out of our video cards? We don’t know why, but we do. That might be the same attitude most people would have when learning about esolangs — esoteric programming languages — we don’t know why people create them or use them, but they do.

We aren’t talking about mainstream languages that annoy people like Lisp, Forth, or VBA. We aren’t talking about older languages that seem cryptic today like APL or Prolog. We are talking about languages that are made to be… well… strange.

INTERCAL

We have to start at the beginning. INTERCAL. This was started as a joke in 1972 and the acronym is purportedly for Compiler Language With No Pronounceable Acronym. There was no actual implementation, though, until around 1990. Now there are two: C-INTERCAL and CLC-INTERCAL.

Since INTERCAL is a parody, it makes some very odd choices. For example, bitwise operators like AND operate with two arguments, but one of the arguments is reversed. That is, the top bit of one operand matches the bottom bit of the second operand. In a nod to social convention, there is a modifier known as PLEASE that you should sometimes use when, for example, reading data as in “PLEASE READ IN.” If you don’t use it often enough, the compile will fail warning you that the program is insufficiently polite. However, if you use it too often, you’ll also get an error that your program is excessively polite.

Originally, the implementation used EBCDIC, so it uses some characters that don’t appear on conventional 7-bit ASCII systems. This forced some character substitutions and now, with Unicode, some versions will allow the old-style characters if you prefer them. The INTERCAL manual renames nearly all the special characters for further confusion. A single quote is a “spark” and the equal sign is a “half-mesh”. Only the ampersand remains unscathed.

Want to know more? Be careful what you wish for.

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Monitor For Bedridden Patients Aims To Improve Care

January 26, 2022 by 11 Comments

One of the joys of being a Maker and Hacker is solving problems and filling needs. When you can do both, well, that’s something special. [rodrigo.mejiasz]’s project surely fits into that special category of solving a problem and filling a dire need with his Bedridden Patient Monitor.

While [Rodrigo]’s project page does not specify his motivation for creating this project, one only needs to look as far as their local hospital ward or senior care facility to understand why this device is so wonderful. Healthcare workers and caregivers are stretched paper thin, and their attention is being constantly interrupted.

This is where the Bedridden Patient Monitor comes in. A healthy person can reposition themselves if they are uncomfortable, but bedridden patients cannot. It’s not just that a bedridden patient is unable to get out of bed, but that they are unable to move themselves without assistance. The result is a great amount of pain. And if left unchecked, pressure sores can be the result. These are not only extremely unpleasant, but an added danger to a patients health.

The Bedridden Patient Monitor steps in and provides not just an egg-timer like alert, but helps caregivers track a patients position in bed across even several working shifts. This ensures a continuity of care that might otherwise be easy to miss.

The beauty of this build is in its application but also its simplicity: it’s just an Arduino Mega, a TFT shield with its Micro SD card, and the touch screen itself. A few LED’s and a buzzer take care of alerts. A thoughtfully configured interface makes the devices use obvious so that staff can make immediate use of the monitor.

Makers have a long history diving into the medical field, such as this stab wound treatment device that won the Dyson award in 2021.

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The SHA2017 Badge Just Keeps On Giving, This Time It’s A Solar Monitor

January 26, 2022 by 2 Comments

Regular readers will know that we have covered the world of electronic badges for many years, and nothing pleases us more than seeing an event badge having a life afterwards rather than becoming a piece of e-waste. Thus we were especially pleased to see [Angus Gratton]’s use of a SHA2017 badge as a solar output monitor, over four years after the event.

The SHA badge used an ESP32 as its processor, and paired it with a touch keypad and an e-ink screen. Its then novel approach of having a firmware that could load MicroPython apps laid the groundwork for the successful open source badge.team firmware project, meaning that it remains versatile and useful to this day.

The solar monitor simply grabs time-series information from the database used by his web graphing system and displays it on the e-ink screen in graph form, but the interest apart from the use of the badge in his treatise on MicroPython coding. He makes the point that many of us probably follow unconsciously, writing for full-fat Python and then fixing the parts which either don’t work or use too many resources on its slimmer cousin. Finally he powers the device from an old phone charger, and shares some tips on controlling its tendency to reboot on power spikes.

It’s almost a year ago that we showed you a SHA badge being used as an environmental sensor.

Thanks [Sebastius] for the tip.

Exercise Bike Hacked As Input For Xbox 360

January 25, 2022 by 12 Comments

If you like playing Grand Theft Auto, you’re pretty familiar with squeezing the triggers for accelerating and braking while driving around. [David Programa] decided this was too easy, and instead developed a system to allow him to pedal his way around the virtual world.

The device relies on a flywheel-based exercise bike, with six magnets placed on the flywheel that triggers a reed switch six times per rotation. The extra magnets give the system better resolution at slow speeds. A Hall Effect sensor would be a more reliable way to build this to survive in the long term, but the reed switch does work. It’s paired with a debounce circuit to keep the output clean. A Raspberry Pi is pressed into service, running a Python program to read a GPIO pin activated by the reed switch, counting pulses to determine the speed of pedalling.

The trigger control used in the Xbox 360 controller is a potentiometer that creates varying voltages depending on its position, allowing it to act as an analog accelerator input. 0 volts corresponds to no input, while the trigger reads 3.3 volts when fully depressed. The Raspberry Pi emulates this with its PWM output, paired with a low-pass filter to create the relevant voltage to inject into the trigger input on a generic Xbox 360 controller.

While it’s a lot less practical than simply using a regular controller, the pedal controls do allow you to get a great workout while playing Grand Theft Auto. Some of the more intense chase missions should be a great way to get your heart rate up, and that’s got to be a good thing.

Ironically, though, the system only works for cars and motorbikes in game. The bicycles in Grand Theft Auto are controlled by mashing the A button instead. Alternatively, you might consider a similar system for playing Mario Kart on the Nintendo Switch. Video after the break.

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