While discussing the design, [Francis] reveals his first pass at the instruction set, discussed what he found wrong about it, and then reveals the final set composed of real instructions and some macros to handle other common cases.
Continue reading “Virtual CPU Stays on Script”
Since an FPGA is just a sea of digital logic components on a chip, it isn’t uncommon to build a CPU using at least part of the FPGA’s circuitry. VexRiscv is an implementation of the RISC-V CPU architecture using a language called SpinalHDL.
SpinalHDL is a high-level language conceptually similar to Verilog or VHDL and can compile to Verilog or VHDL, so it should be compatible with most tool chains. VexRiscv shows off well in this project since it is very modular. You can add instructions, an MMU, JTAG debugging, caches and more.
Continue reading “VexRiscv: A Modular RISC-V Implementation for FPGA”
It is easy to dismiss bash — the typical Linux shell program — as just a command prompt that allows scripting. Bash, however, is a full-blown programming language. I wouldn’t presume to tell you that it is as fast as a compiled C program, but that’s not why it exists. While a lot of people use shell scripts as an analog to a batch file in MSDOS, it can do so much more than that. Contrary to what you might think after a casual glance, it is entirely possible to write scripts that are reliable and robust enough to use in many embedded systems on a Raspberry Pi or similar computer.
I say that because sometimes bash gets a bad reputation. For one thing, it emphasizes ease-of-use. So while it has features that can promote making a robust script, you have to know to turn those features on. Another issue is that a lot of the functionality you’ll use in writing a bash script doesn’t come from bash, it comes from Linux commands (or whatever environment you are using; I’m going to assume some Linux distribution). If those programs do bad things, that isn’t a problem specific to bash.
One other limiting issue to bash is that many people (and I’m one of them) tend to write scripts using constructs that are compatible with older shells. Often times bash can do things better or neater, but we still use the older ways. For example:
Continue reading “Linux Fu: Better Bash Scripting”
July 20th, 1969 was the day that people from Earth set foot on different soil for the first time. Here we are 48 years later, and the world’s space programs are — well — not very close to returning to the moon. If you aren’t old enough to remember, it was really amazing. The world was in a lot of turmoil in the 1960s (and still is, of course) but everyone stopped to look at the sky and listen to the sound of [Neil Armstrong] taking that first step. It was shocking in a good way and almost universally observed. Practically everyone in the world was focused on that one event. You can see some of that in the NASA video, below.
Space flight was an incredible accomplishment, but it paled in comparison with the push to actually landing a person on the moon and bringing them home safely. The effort is a credit to the ability of people to work together (on the order of thousands of minds) to overcome a difficult challenge. We can learn a lot from that alone, and it makes a compelling argument to continue taking on tough problems. Today, as we remember the Apollo landings, let’s take a moment to recognize what came of it beyond an iconic boot-print in the floury lunar soil.
Continue reading “Beyond a Boot Print: The Lasting Effect of Apollo on Humanity”
Silent film star [Lon Chaney] had the nickname “man of a thousand faces.” The Try It Out website (tio.run) might well be the site of a hundred languages. Well, in all fairness, they only have 97 “practical” languages, but they do have 172 “recreational languages” but the site of 269 languages doesn’t trip off the tongue, does it? The site lets you run some code in each of those languages from inside your browser.
By the site’s definition, practical languages include things like C, Java, Python, and Perl. There’s also old school stuff like FOCAL-69, Fortran, Algol, and APL. There’s several flavors of assembly and plenty of other choices. On the recreational side, you can find Numberwang, LOLCODE, and quite a few we’ve never heard of.
Continue reading “The Site of a Hundred Languages”
The documentation is a bit sparse but readable. You simply define the function you want to execute and the dimensions of the problem. You can specify one, two, or three dimensions, as suits your problem space. When you execute the associated function it will try to run the kernels on your GPU in parallel. If it can’t, it will still get the right answer, just slowly.
Hackaday readers don’t need an introduction to the Arduino. But in industrial control applications, programmable logic controllers or PLCs are far more common. These are small rugged devices that can do simple things like monitor switches and control actuators. Being ruggedized, they are typically reasonably expensive, especially compared to an Arduino. [Doug Reneker] decided to evaluate an Arduino versus a PLC in a relatively simple industrial-style application.
The application is a simple closed-loop control of flow generated by a pump. A sensor measures flow for the Arduino, which adjusts a control valve actuator to maintain the specified setpoint. The software uses proportional and integral control (the PI part of a PID loop).
Continue reading “PLC vs Arduino Show Down”