At FCCM 2026 I saw a keynote by Onur Mutlu on abusing DRAM chip timings to have them perform vector (row) copies and even or/and/nand computations on entire rows, 'for free' (happens physically through capacitors charge). And this is on current, off-the-shelves DDR3/DDR4 memory!
Well, I've got a bunch of great FPGA boards featuring good old SDRAM chips and ...
It turns out RowClone is possible on older SDRAM chips!
The TMDS clock wasn't meeting timing on #ULX3S. There is so little logic in the clk_pix_5x domain I doubted I could do much. Then I realised each channel shared a small critical ring counter. Giving each colour channel its own added 100 MHz+ to the max frequency! #FPGA 🚀
https://github.com/projf/isle/blob/main/hardware/arch/ecp5/dvi_generator.v
Made some time for 🏝️ Isle.Computer today. Getting the graphics registers working across clock domains so the CPU can double buffer, scroll, adjust transparency etc. #FPGA
Images show RISC-V CPU reading graphics registers in sim and on #ULX3S.
The @RadionaOrg ULX3S hub site now honors device dark mode! Sunglasses no longer needed 😎
I also added a Tiny Tapeout section, as (pending a few Pull Request merges) @latticesemi #ECP5 FPGA support for testing your ASIC design on the #ULX3S is coming to @tinytapeout
You can find the source code on GitHub (I'm considering moving to Codeberg): https://github.com/projf/isle
Includes everything you need for:
* @machdyne Lakritz (Lattice ECP5)
* Digilent Nexys Video (Xilinx XC7)
* Radiona #ULX3S (Lattice ECP5)
* Verilator simulator with SDL (Linux/macOS/Windows)
And a quick lunchtime shot of 🏝️ Isle.Computer running on #ULX3S.
Simulation may be practical for software dev, but it feels so much better seeing it running on real hardware. This is #riscv asm decoding UTF-8 sent over UART to Isle hardware running on #fpga. Verilog and asm written by hand. 😊
You can find the open-source designs and instructions for 🏝️ Isle FPGA computer at: https://github.com/projf/isle
You can run Isle on Linux/Mac/Windows under simulation, and it's really easy to set up.
Plus, there's board support #ULX3S, @machdyne Lakritz, and Digilent Nexys Video.
sylefeb
Flux
gojimmypi
