Flux

1 Aug 2025

Isle 🏝️ is my new #FPGA project. Isle is a simple, modern computer — an open design that encourages tinkering, experimentation, and doing your own thing. I hope to inspire you to come on a journey with me and build your own computer. projectf.io/isle/fpga-co...

freebsd.org The FreeBSD Project

I’m happy to see #FreeBSD has FRED support. One day, when memory is affordable, this will come in handy, particularly for servers. www.freebsd.org/status/repor...

projectf.ioECP5 FPGA Clock GenerationYosys and nextpnr have excellent support for Lattice ECP5 FPGAs. However, without using the ECP5 PLL (phase-locked loop), you’re stuck running at the speed of your dev board oscillator. This post outl...

If you're working with ECP5 #FPGA, I recommend learning how to control the PLLs to set your own clock frequencies, for example, to generate video signals or interface with DRAM. projectf.io/posts/ecp5-f... PS. Hand written blog with no ads or tracking. Just content. Happy #FPGAFriday 🕰️

FreeBSD FreshPorts is back online. Hooray. Now we just need those pkg servers to finish building…

New (secondhand) book to help me develop 🏝️Isle.Computer floating point in #riscv asm. Subnormals seem much easier in software than hardware. 😄

github.comGitHub - ulfjack/ryu: Converts floating point numbers to decimal stringsConverts floating point numbers to decimal strings - ulfjack/ryu

Floating point to decimal string conversion is one of the trickiest parts of rolling your own library. It’s kind of mind blowing that “Ryū: fast float-to-string conversion” was published as recently as 2018! github.com/ulfjack/ryu

The lesser-known #Amstrad fondue computer. Does anyone know anything about its architecture?

22 Sept

Fascinated Wikipedia clicking always leads to knowledge. Whether this is worthwhile knowledge is left as an exercise for the reader. “At one stage in 1981, three of the top ten best selling books in the US were books on solving Rubik's Cube...”

“The plot of the 1971 comedy film Lady Liberty, starring Sophia Loren, is based on the United States ban on mortadella.”

Flux reposted

Lynn™

@lynn.cat

21 Sept

demos in the 1990s: chrome sphere on chessboard demos in the 2020s: chrome sphere in dimly lit room

Flux reposted

github.comisle/boards/verilator at main · projf/isleIsle FPGA Computer. Contribute to projf/isle development by creating an account on GitHub.

13 Sept

Replying to @willflux.bsky.social

Can you help? #FPGA I'd like to collect some Isle.Computer Verilator simulation performance from a range of systems. Please run the Verilator simulation of the Isle ch07 design, setting conf.bench_frames = 100; in main_ch07.cpp. Thank you. ☺️ See github.com/projf/isle/t... for instructions.

12 Sept

New draft 🏝️ Isle.Computer blog post: projectf.io/isle/graphic... “This post is a tale of two devices: Display and Earthrise. These graphic devices make the graphics CPU programmable for the first time.“ #FPGA

github.comisle/boards/verilator at main · projf/isleIsle FPGA Computer. Contribute to projf/isle development by creating an account on GitHub.

13 Sept

13 Sept

Both my M1 MacBook Air and Framework i5-1240P Linux laptop get 18.5 FPS (165 ns/cycle) with ch07. My Linux laptop is much faster in performance mode than balanced. The simulation is single threaded. So, I'm particularly interested to see how fast the Ryzen 9000 and latest Apple Silicon are.

gitlab.comQEMU emulator version 6.0.50 Failure with nested FreeBSD bhyve (#337) · Issues · QEMU / QEMU · GitLabBUG: Starting FreeBSD Layer 2 bhyve Guest within Layer 1 FreeBSD VM Host on Layer 0 Ubuntu 21.04 KVM / QEMU Host results in Layer 1...

10 Sept

The open-issue emotional roller coaster. 🎢 Hooray, there's an issue for this... oh no, it's been open since 2021! Issue affects nested #qemu virtualisation with #FreeBSD: gitlab.com/qemu-project...

🏝️ Isle.Computer is my #FPGA computer from scratch. Exciting new features have been in short supply of late due to life and spending the time I have on improving existing designs/Verilog. I'm now getting back to: * Display Device * Debug Monitor * Dynamic devices with MMIO * Codeberg migration

1 Sept

Deleting unneeded hardware is satisfying. I realised my degenerate triangle handling logic is no longer needed. Triangles where all vertices are coincident, or in a line, render correctly. 📐

10 Sept

Quick 🏝️ Isle.Computer status update. The latest Isle design is already merged in git. I'm currently writing the next blog post. Once that's live, I plan to work on the debug monitor and migration to Codeberg.

github.comisle/boards/verilator/profiling.md at main · projf/isleIsle FPGA Computer. Contribute to projf/isle development by creating an account on GitHub.

10 Sept

I've been attempting to speed up my 🏝️ Isle.Computer #Verilator sim with profiling. I've added some brief notes on how I profiled on Linux: github.com/projf/isle/b... #FPGA

4 Sept

Verilog hates you. If reg [7:0] wptr; and wptr=255 these expressions are completely different: wptr + 1 == 0 wptr + 1'b1 == 0 I blogged about this yet it still caught me out: "Verilog uses the width of the widest operand when evaluating an expression". The width of 1 is 32 bits because #Verilog.

docs.cocotb.orgRelease Notes — cocotb 2.1.0 documentation

2 Sept

Just spotted a new release of cocotb: docs.cocotb.org/en/v2.1.0/re... A long list of changes to get my head around. Not sure of the implications yet. I wonder if my existing 2.0 tests will run OK? Nice that Python 3.14 is now supported. #verilog #fpga

16 Aug

Looks like I've found a real hardware rendering bug. I've only tested this in Verilator/SDL sim so far, but time for me for me to call it a night. I can check it on FPGA when I'm back at my desk. 😴

22 Aug

With scroll hardware registers fixed, here’s a demo of draw and display scrolling hardware. #ULX3S #FPGA

Met Office - weather and climate

17 Aug

Looking forward to seeing Arcadia on the stage for the first time.

Flux reposted

@metoffice.gov.uk

13 Aug

Temperatures provisionally reached 38.1°C at Kew Gardens, making it the hottest day of the year so far. This is the second time this year we have reached 38°C. The only other time this has happened twice in one year was in 2022. It also makes it the 5th hottest day on record.

11 Aug

Testing CPU control of the Earthrise graphics engine. Open source designs running on an ECP5 #FPGA.

13 Aug

It's too hot to think clearly. 🥵 While working on my hardware graphics engine, I was dismayed to discover a new hardware scrolling bug. On closer inspection it turns out to be an error in my RISC-V asm. ☺️ You can see the broken version running here in simulation.

youtu.beRevision 2019 - Compo - Amiga DemoYouTube video by Revision Demoparty

12 Aug

There's a solar #eclipse today. A good excuse to watch Eon by TBL (feel those goosebumps at Revision): youtu.be/zwoyfH7TgEQ?... #amiga #demoscene

Flux reposted

Met Office - weather and climate

@metoffice.gov.uk

8 Aug

The UK will experience a partial solar eclipse on Wednesday 12 August. The extent of the Sun's coverage and the timing of maximum obscuration will differ across the country. Never look directly at the sun; use a pinhole projector or certified eclipse glasses to view it.

3 Aug

Oh no, there's a translation bug in my hardware 2D drawing engine... wait no, my docs aren't clear enough (even to me). Translation only affects coordinates set *after*. 😮‍💨 Docs revised. Now I can move onto CPU controlled animation testing.

5 Aug

The Earthrise drawing engine assembler now outputs memory offsets and the mnemonics assembled. The drawing engine uses 16-bit instructions, but a 32-bit bus to match the 32-bit RISC-V CPU. While I'm big endian at (68K) heart, Earthrise is little endian to match RISC-V.

3 Aug

Hastings weather station recorded 1.2 mm of rain for the month of July.

metoffice.gov.ukHistoric July sees record dryness, unprecedented sunshine and exceptional warmthJuly 2026 has been an exceptional month for the UK's climate statistics, with records challenged or broken for rainfall, temperature and sunshine, according to provisional Met Office statistics.

3 Aug

July weather was exceptional. Southern England had its driest, sunniest, and hottest month on record. The rainfall records go back to 1836! 🫠 www.metoffice.gov.uk/about-us/new...

projectf.ioIsle FPGA Computer

1 Aug

I've just realised it's one year since I first wrote about 🏝️ Isle.Computer. I believe the case for simple, open hardware is as compelling as ever. I look forward to releasing the next chapter this month. ☺️ #FPGA #OpenHardware projectf.io/isle/fpga-co...

31 July

Pleasantly surprised to find Verilog support built in to @panic.com Nova 14. Perhaps less surprisingly, it's also 10x less memory hungry than VS Code.

31 July

So, it turns out this is an extension, not built in, but it still seems to work well.

25 July

🏝️ Isle.Computer doesn't have interrupts yet, but catching bus faults is still handy, especially when running software under Verilator simulation. Here's the code I worked on this morning. #FPGA

30 July

Done a bit of work on the 🏝️ Isle.Computer graphics devices today. Here's a 16 colour compositor test running under simulation. #FPGA

26 July

It’s raining! 🌧️ It’s been so long, I’ve almost forgotten what rain is. Europe is very dry this summer.

19 July

One courgette on the allotment managed to hide amongst the leaves.

The display device composites different graphics together, e.g. text mode and bitmap layers, with scrolling, transparency and double buffering. The debug monitor lets you debug from the inside, wozmon style. Dynamic MMIO devices allow hardware to automatically work in different "slots".

16 July

I've snuck in a little work on the display device. Getting the display control signals to work across hardware modules, hardware registers, and software takes some doing, especially after recent renaming and refactoring. Having scrolling and transparency under software control is fun though. ☺️

16 July

I try to learn from past hardware, but I have to wonder what Sega were thinking with the Saturn architecture. Just look at the motherboard! I don’t envy game devs starting out with it. www.copetti.org/writings/con...