Collaborate Disseminate
It isn’t for everyone, but if you work much with computers at a low level, you’ll probably sooner or later entertain the idea of creating your own CPU. There was …read more Continue reading Scott’s CPU From the Bottom Up
We are certainly spoiled by all the microcontroller options nowadays — which is a great problem to have. But between the good old 8-bit controllers and an increasing number of 32-bit varieties, it almost seems as if the 16-bit ones are slowly falling into oblivion. [stnolting] particularly saw an issue …read more
Continue reading NEO430 Puts A Custom MSP430 Core In Your FPGA
A rite of passage for a digital designer is to build a CPU. That may seem a formidable task and if you are thinking of building a modern CPU like the one in your PC, it is. However, a simple CPU is well within the reach of anyone who can sling some logic gates or HDL. We’ve even seen CPUs built in Minecraft. Now you can play nandgame and build a CPU step-by-step in your browser.
The game is based on the popular From NAND to Tetris site. True to the name you start out with a single NAND gate …read more
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.
When you build a CPU in FPGA, …read more
Continue reading VexRiscv: A Modular RISC-V Implementation for FPGA
[Ben Eater] posted some videos of an 8-bit computer with no CPU chip that he built completely on a breadboard a few years ago. After being asked for schematics, he finally admitted that he didn’t have any. So, instead, he decided to rebuild it and keep a video log of each step in the process. You can see his kickoff video, below, but you can also find 30 more recent videos covering topics from the ALU design and troubleshooting to the decimal LED display. He even uses an Arduino to program a EEPROM that he uses to replace a lot …read more
[Agp.cooper] saw a vintage 4Kx4 bit RAM chip and decided that it needed a CPU design to match. The TTL design fits on two boards and has a functional front panel.
This custom CPU project has a few interesting bits worth noting. First, it is small enough that you can wrap your head around it pretty easily. And [Agp.cooper] gives a good account of the instructions set architecture choices he considered and why he settled on the final design.
Another interesting twist is the testing. Each of the boards can mate with an Arduino which will exercise and test its …read more
