If you have a signal that passes through a capacitor or transformer, you will lose the DC portion of the signal. What do you do? If you need it, you can restore the DC bias using various techniques, as [Sam Ben-Yaakov] shows in a recent video.
These types of circuits were common in analog TVs, and, in fact, [Sam] shows the schematic of a TV to explain the need for the DC level. In that case, a vacuum tube diode does the work, but a solid state one will do the same job.
Since China State Shipbuilding Corporation (CSSC) unveiled its KUN-24AP containership at the Marintec China Expo in Shanghai in early December of 2023, the internet has been abuzz about it. Not just because it’s the world’s largest container ship at a massive 24,000 TEU, but primarily because of the power source that will power this behemoth: a molten salt reactor of Chinese design that is said to use a thorium fuel cycle. Not only would this provide the immense amount of electrical power needed to propel the ship, it would eliminate harmful emissions and allow the ship to travel much faster than other containerships.
Meanwhile the Norwegian classification society, DNV, has already issued an approval-in-principle to CSSC Jiangnan Shipbuilding shipyard, which would be a clear sign that we may see the first of this kind of ship being launched. Although the shipping industry is currently struggling with falling demand and too many conventionally-powered ships that it had built when demand surged in 2020, this kind of new container ship might be just the game changer it needs to meet today’s economic reality.
That said, although a lot about the KUN-24AP is not public information, we can glean some information about the molten salt reactor design that will be used, along with how this fits into the whole picture of nuclear marine propulsion.
Continue reading “China’s Nuclear-Powered Containership: A Fluke Or The Future Of Shipping?”
Switching inputs between desktops seems like something that should be simple but can prove to be a pain in reality. [Hrvoje Cavrak] decided to take matters into his own hands and build a better keyboard and mouse switch.
DeskHop is built from two Raspberry Pi Pico boards connected via UART and separated by an Analog Devices ADuM1201 dual-channel digital isolator. Through the magic of Pico-PIO-USB these RP2040s can be both host and device. To keep things simple, the PCB is single-sided, and the BOM only has five distinct components.
Once hooked up to your Windows, Mac, or Linux device, your mouse pointer “magically” goes from one screen to the other when dragged across the screen edge. Keyboard LEDs can be reprogrammed to indicate which device is active, and the real beauty of the device is that since it’s a hardware solution, you don’t have to install any software on a computer you might not have admin access to.
If you want to see some more ideas for keyboard and mouse switching, check out this Pi KVM with ATX signaling, this USB triplexer, or this Pi KVM on a PCIe card.
Last time, I talked about racing the beam, a type of graphics used when memory was scarce. Now it’s time to step into the future with more memory and talk about what modern 2D games still do to this day: rasterization.
Continuing the trend set by racing the beam, rasterized graphics are also on a grid, just a much tinier one. Though not unique to rasterized, the “frame buffer” is the logical conclusion of bitmap mode fidelity: enough memory is allocated so that every pixel can have its own color. What’s different about a frame buffer is that everything is drawn before it is shown and, crucially, this doesn’t have to happen in the same order as the pixels are displayed. Rasterization draws entire shapes — triangles, lines and rectangles — into the frame buffer and the screen is typically updated all at once. Continue reading “Game Graphics: Rasterization”
Despite the popularity of the IBM PC in the West during the 1980s, it had shortcomings that prevented it from flourishing in the Japanese market, most of all support for the Japanese language. This led to a sort of parallel universe in which NEC’s PC-9800 series (‘PC-98’) was the dominant personal computer, including its NEC µPD7220 display controller with its 4096-color palette. These computer systems led to a graphics style that persists to today, along with a whole ecosystem of games and applications that never left the PC-98. In an article by [Biz Davis] this software ecosystem, its art style and their lasting impact is explored.
Although the NEC PC-9800 series of computers was primarily focused on Japanese businesses with its release in the early 1980s, it found itself adopted for educational and hobby purposes as well. During the 1980s and early 1990s they faced little opposition from IBM PCs and clones, despite them all being x86-based systems running DOS. It wasn’t until the early 1990s that mostly US companies began to explicitly design computers to work for the Japanese market, leading to a gradual decline of the PC-9800 series PCs in the market.
Despite the last PC-98 system having been released in 2000 – with the last systems running some flavor of Windows – these systems and the software for them isn’t just a unique time capsule of this part of Japan’s history, but continues to see new software releases to this day. If you wish to experience this software for yourself, a number of open source PC-9800 emulators are available, including the nyan-tastic Neko Project II.
Top image: PC-9801 system. (Credit: MH0301 – Own work, CC BY-SA 4.0)
What do you get when you join a slide projector and a digital camera? Filmolimo, an open source slide scanner. The scanner uses an M5Stack Fire, an ESP32 development board. Thanks to the ESP32, you can control the device via WiFi.
All the project files, including KiCAD design files, are on GitHub. Of course, you will probably have to adapt things to your specific camera and slide projector. The PCB is double-sided and looks easy to put together. The board is mostly opto-isolation and interface between the controller and the equipment. The software allows you to change things like the time between slides, for example.
This is one of those projects you probably only need for a bit. Unless, of course, you regularly scan slides. You can farm it out to a service provider, but what fun is that? If you have a few hundred thousand slides, you might need to go for speed. If you just have a few, you can get by with a simple adapter.
If you were to talk about sixteen bit computing in retrocomputing circles, misty-eyed reminiscences of the ST or Amiga would emerge. Both fine platforms, but oddly the elephant in the 16-bit room has become a victim of its own success. DOS, the granddaddy of all PC operating systems, seems oddly overshadowed by its 68000-based competitors in a way it certainly wasn’t back in the day. Perhaps it’s the often-atrocious graphics when cards designed for business graphics were pressed into gaming service, but it’s easy to forget that DOS PCs were the powerhouses of their day. They still pack a punch even in 2023, as [Lunduke] is here to show us by running a DOS web server. Take that, nginx! Continue reading “A Web Server, The Sixteen Bit Way”
