What do you do when you decide that running CP/M on a Commodore 128 with a 5.25″ drive “Isn’t CP/M enough”? If you are [Chris Osborn], you reach for your trusty TRS-80 Model II, with its much more CP/M-appropriate 8″ drive.
There was one small snag with the TRS-80 though, its keyboard didn’t work. It’s a capacitive device, meaning that instead of each key activating a switch, it contains a capacitive sensor activated by a piece of aluminized Mylar film on a piece of foam. Nearly four decades of decay had left the foam in [Chris]’s example sadly deflated, leaving the keys unable to perform. Not a problem, he cast around for modern alternatives and crafted replacements from a combination of foam weather strip and metalized gift wrap.
Care had to be taken to ensure that the non-metalized side of the gift wrap faced the capacitive sensor pads, and that the weather strip used had the right thickness to adequately fill the gap. But the result was a keyboard that worked, and for a lot less outlay and effort than he’d expected. We would guess that this will be a very useful technique for owners of other period machines with similar keyboards.
What is CP/M, I hear you ask? Before there was Linux, Windows, and MacOS, there was DOS, and before DOS, there was CP/M. In the 1970s this was the go-to desktop operating system, running on machines powered by Intel’s 8080 and its derivatives like the Zilog Z80 in the TRS-80. When IBM needed an OS for their new PC they initially courted CP/M creators Digital Research, but eventually they hired a small software company called Microsoft instead, and the rest is history. Digital Research continued producing CP/M and its derivatives, as well as an MS-DOS clone and the GEM GUI that may be familiar to Atari ST owners, but were eventually absorbed into Novell in the 1990s.
[Thomas] loves his Logitech MX Master mouse, which has a pretty elaborate scroll-wheel mechanism. Perhaps too elaborate; it broke on him after a week of use, just when he was getting used to the feature. So what did he do? Took it apart and fixed it, naturally. And as a bonus, we get a guided tour of the interesting mechanism. Check out his video below to watch it in action.
The weighted scroll wheel switches between two different modes, one with a detent like you’re probably used to, and one where the wheel is allowed to spin freely for long-distance travel. And to do this, it’s actually got a little motor inside that rotates a cam and throws a lever into the side of the scroll wheel for the detent mode, and pulls the lever out of the way for free spins. It must also have some logic inside that detects how quickly the scroller is spun because it re-engages as soon as the scroll wheel stops.
On display at the PAX East gaming expo, the keys on 160 Logitech keyboards make up the “pixels” of a video wall showing a short film inspired from side-scroller video games. It’s the work of the production company iam8bit. Details on the system are scant, but we can learn a little from close observation of the video.
In 2013 the dean of an Ethiopian university addressed Maker Faire Hannover and outlined one of his concerns; that the high price of developed-world textbooks was holding back the cause of education for universities such as his own in developing countries. He was there to ask for help from the maker community to solve his problem, and a group of his audience took up the challenge to create an affordable and accessible automatic book scanner.
Their scanner builds on the work of Google engineer [Dany Qumsiyeh], whose open source linear book scanner turns pages by traversing the opened book over a triangular prismic former such that pages are turned by vacuum as they pass over carefully designed slots in its surface. Their modification replaces the vacuum with the Coandă effect, to more gently tease open each page and it is hoped reduce the chance of damaging the volumes being scanned.
The whole machine is controlled by a Raspberry Pi, and the scanning is performed by linear scanning optics, sensors, and electronics taken from flatbed scanners.
An important design goal of the project was to ensure that the scanner could be built without special tools or expertise that might be difficult to find in a developing country, as well as that it should be as inexpensive as possible. The frame of the machine is off-the-shelf extruded aluminium, and the body is acrylic sheet which can be cut to shape with a hand saw if necessary. It is estimated that the device will cost in the region of 500 Euros (about $568) to build.
Writing from the perspective of having been peripherally involved in a professional book scanning operation at a large publisher the benefits of this machine are immediately apparent. Removing the binding and automatically scanning each page as an individual sheet produces a very fast and high quality result, but by its very nature damages the volume being scanned. This machine promises to deliver a solution to the problem of book scanning that is considerably less intrusive.
It is also worth noting that the project does not address any copyright issues that might arise from scanning commercially published textbooks, though this is more of a concern for the end user in terms of what they scan with it than it is for the maker.
There’s a reason that the bog-standard serial port will never die. It’s just so robust and simple. When you need a console that will absolutely work with minimal software and hardware, UART is the way to go. Because of this, UART hacks abound. Here’s a new one to us, and a challenge to our readers.
[Tiziano Bacocco] decided to use UART signals as a type of PWM to create audio. That’s right, he’s plugging the serial TX line straight into a speaker. This gives you eight possible PWM output voltage levels. The trick is using some Python code (using the awesome pyserial module) to down-quantize the audio data to fit these eight possible values and then push them out at the correct sampling rate. ffmpeg is used to pre-process the files.
There are a number of ways to control an automobile without using the pedals, and sometimes even without using the steering wheel. Most commonly these alternative control mechanisms are installed in vehicles whose owners are disabled in some way, but [Anurag] has taken this idea of alternative control one step further. He has built a car that can be driven by hand gestures alone.
On a remote controlled car, a Raspberry Pi 2 was installed that handles processing and communication. A wireless network is created on the Pi, and a laptop connects to the Pi over the network. The web camera on the laptop regularly captures frames at 15 fps to check for the driver’s hand gestures. The image is converted to gray scale, thresholded, contours are obtained, and the centroid and farthest points are obtained.
After some calculations are done, a movement decision is taken. The decision is passed to the Pi, which in turn, passed that to the internal chip of the car. All of the code is available on the project’s github page. [Anurag] hopes that this can be scaled up to full sized cars in the future. We’ve seen gesture-based remote controls before that rely on Sonar sensors, so it’s interesting to see one that relies strictly on image processing.
[TK] is a retro computer enthusiast who’s had some difficulty locating a joystick for his trusty Amiga 500. New ‘sticks are expensive, and battered survivors from the 80s go for more than they should.
Happily these old controllers were simple devices, having only five control lines for the four directions and a fire button which were active low. [TK] therefore cast around the available components and decided to craft his own controller from a numerical keypad.
Numerical keypads may be ubiquitous, but they’re not the perfect choice for a joypad. Instead of individual switches, they are wired as a matrix. [TK]’s controller works within that constraint without butchering the keypad PCB, though his layout has the left and right buttons below the up and down buttons. Looking at the schematic we wonder whether the 4-5-6 and 7-8-9 rows could be transposed , though joypad layout is probably a matter of personal choice.
Making the controller was a simple case of wiring the pad to a 9-pin D socket in the correct order, and plugging it into the Commodore. He reports that it’s comfortable to use and better than some of the lower-quality joysticks that were on the market back in the day. Veterans of Amiga gaming will understand that sentiment, there were some truly shocking offerings to be had at the time.