icestorm

I'd also vote for an FPGA Mainboard, ideally Lattice, ideally iCE40, and ideally compatible with Project IceStorm (Yosys, Arachne-pnr, and IceStorm) open source tools: https://github.com/YosysHQ/icestorm Think something similar to MiSTer FPGA -- but in a laptop form factor, and able to run all sorts of "soft" CPUs on it, including (but not limited to) the following: https://opencores.org/projects?expanded=Processor

As others have already mentioned the Lattice ice40 family is supported by OSS chains through project icestorm [0]. There were some nice boards floating around though you may have to watch out for supply chain issues still plaguing this market. Examples: - icoboard: has the 8k LUTs chip, comes with soldered PMODs[1], if you get it watch out as you either need a RaspberryPI with GPIOs soldered to program it, or you purchase their USB FTDI interface in addition. See: http://icoboard.org/ - iCEBreaker, comes with the 5k LUTs chip, has the USB-FTDI interface built-in, but you need to solder the PMODs yourself. See: https://www.crowdsupply.com/1bitsquared/icebreaker-fpga#prod... [0] https://github.com/YosysHQ/icestorm [1] https://digilent.com/reference/pmod/start

Despite the last entry on the linked page being in 2018, the source repository shows that it is an active project. https://github.com/YosysHQ/icestorm From memory (simple?) VHDL is supported by using gHDL as a synthesis engine, the output of which can feed into the yosys/icestorm tool chain? https://ghdl.github.io/ghdl/using/Synthesis.html https://github.com/ghdl/ghdl-yosys-plugin

>The rest of this page explains how to compile and install a "bitstream" file to implement this processor in a cheap (about $50) FPGA board, then how to build Linux for that board and boot it to a shell prompt. >Numato: The cheapest usable FPGA development board ($50 US) the j2 build system currently targets is the Numato Mimas v2 (also available on amazon). It contains a Xlinux "Spartan 6" LX9 FPGA that can run a J2 at 50mhz, 64 megs of SDRAM, USB2 mini-B, and a micro-sd card slot. PDS: Nice! But, it would be an additional serious "would be nice"(!) -- if this could run on Lattice FPGA's / IceStorm Open Source Toolchain: https://www.latticesemi.com/Products http://www.clifford.at/icestorm/ https://github.com/YosysHQ/icestorm

I've so far been quite happy with the iCE40UP5k[1] based dev kit I got, though there are a lot of options out there[2]. The iCE40 FPGAs are a bit whimpy compared to Altera and Xilinx offerings from what I understand, but I really liked the idea of an open-source toolchain[3][4] being available. To get a taste without committing cash you could just use a simulator[5], which I imagine you'd be using a fair bit anyway as it allows you easier access to the internal state. As to actually programming, I've found the following resources useful. I started with Verilog mainly because code-gen tools like nMigen[6] generate Verilog, but for writing by hand it seems VHDL is preferred. Anyway, links, first off some exercises to get going[7]. Introduction to Verilog[8], also has a nice general overview of HDL. Details of how non-blocking vs blocking st

Lattice iCE40 is documented [1] and it has fully open source development tools [2], [3] [1] https://github.com/cliffordwolf/icestorm [2] http://www.clifford.at/yosys/ [3] https://github.com/cseed/arachne-pnr