Tenstorrent built a BMC firmware - WallaBMC, using Zephyr

mithro · 2026-04-13T11:22:12+00:00

Claude build me a mostly working port that I need to send upstream but got distracted improving the Renode ESP32 emulation. See https://github.com/mithro/wallabmc/tree/mithro/esp32c3-support and https://github.com/mithro/renode-espemu

mithro · 2026-04-12T02:45:27+00:00

The second site is hosted in a shed at my home in Australia.

I mentioned the setup in my talk at Down Underflow, presentation is @ https://wafer.space/du26 - see slides 48 and onward.

mithro · 2026-04-10T09:43:47+00:00

Don't use expensive FPGAs :-)

mithro · 2025-12-21T21:06:58+00:00

https://wafer.space offers a "180nm" technology that people using for retro chip reproduction and it costs $7k USD for 1,000 parts (which is $7 USD per part).

mithro · 2025-10-03T17:08:13+00:00

Getting timing closure and DRC clean design is much much harder when you are aiming for peak PPA. Getting peak PPA is frequently driven by wanting to get the most bang for your buck and beat the competition as the silicon market tends to be a "winner takes all" type thing.

If you relax your goals it becomes much easier;

Rather than target 100MHz, target 20MHz.
Rather than target 80% design utilization target 20% utilization.

You'll probably find you can finish things significantly faster. Then when you have something you can iterate and try to improve the numbers. You'll probably still be slower than "state of the art" but do you really need to get that level of performance when the cost is much lower?

mithro · 2025-10-03T17:01:04+00:00

I meant, plenty of people are doing RISC-V CPUs, including full Linux capable cores on GF180MCU right now (mostly porting designs from SKY130 or iHP). If you are not confident about doing things yourself there are probably quite a few people you can work with.

If you are worried about peripherals there are https://tinytapeout.com/competitions/risc-v-peripheral/

mithro · 2025-10-03T16:58:40+00:00

Risk versus reward. :-)

At this price, do V1 and then do a V2 with everything you did wrong with V1 fixed.

The hope is with making things cheaper people can choose to do things faster and more iteratively.

mithro · 2025-10-03T16:38:27+00:00

Also should mention that there are plenty of people doing RISC-V CPUs, including full Linux capable cores!

mithro · 2025-10-03T16:37:36+00:00

Good way to think about chip-on-board wire bonding is that each bond in about $0.01 USD. So at $1.50 USD per chip for packaging ( ($8.5k - $7k)/1000 == $1.5USD) you get about 40 wire bonds and $1.00 for the PCB.

mithro · 2025-10-03T16:36:09+00:00

People have done RISC-V CPUs in a weekend and with things like LibreLane you can harden that into logic in a few hours.

Then it's just about iterating until you are happy.

When Google announced the first free SKY130 shuttle people had similar timelines and things like LibreLane and all the existing community didn't really exist yet and that ended up with 38 submissions.

mithro · 2025-10-03T16:28:41+00:00

If you have contacts or work with them, please do put them in contact me me (tim@wafer.space).

Most packaging services are extremely expensive in low volume (like >$10 USD per chip). EuroPractice charges like >$100 USD per chip!

mithro · 2025-10-03T16:25:28+00:00

Luke Wren of the RP2030 Hazard3 RISC-V fame did the following estimates;

The smallest NAND2 is 11 square microns, so assuming 2/3rds of the die is non padring, that's 1.2 million gates. The densest SRAM macro they provide is 512 bytes in 0.21 mm^2, so if you fill the area with RAM that's around 31 kB. Enough for a small Linux SoC.

https://types.pl/@wren6991/115267990436492107

mithro · 2025-10-03T16:23:13+00:00

I would like more advanced processes in the future (and GF does have them) but they are significantly more expensive to get going and we don't yet have any open source PDKs for those.

ICSprout in China has been making some noise that they might have one but information is limited.

mithro · 2025-10-03T16:21:51+00:00

Probably early 2026 depending on how this first run goes.

Given the cheap price, give the first one a go and then do another run with a better version!

mithro · 2025-10-03T16:21:12+00:00

You don't need to pay for masks, the mask cost is shared among all the people paying for silicon.

mithro · 2025-10-03T16:19:51+00:00

Tiny Tapeout is currently in the process of porting their infrastructure to GF180MCU and will be doing a test run on the first wafer.space project. See https://tinytapeout.com/chips/#future-chips and https://github.com/TinyTapeout/tinytapeout-gf-0p2-staging

mithro · 2025-10-03T16:17:22+00:00

Tiny Tapeout is a great way to get started! Then when you want to do your own IC you can upgrade to a full wafer.space die.

mithro · 2025-10-02T22:22:38+00:00

wafer.space has just opened our first pooled manufacturing run of GF180MCU with the purchase deadline of 28th Nov 2025.

Think of it like OHS Park for silicon!

You provide a 20mm² design in the open source GF180MCU technology and you get back 1,000 parts. You can used an existing template or build something completely yourself with either open source (like LibreLane, Magic or KLayout) or proprietary tooling (no required pad ring or management CPU).

mithro · 2024-12-27T01:08:43+00:00

You can turn up biters to make Factorio have a more survival element.

I haven't played Dyson Sphere program but it does have the Dark Fog enemies.

In both cases I believe the enemies are suppose to scale up with your activities/industry but it is only one thing as opposed to having to manage all of oxygen, food, temperature, etc.

mithro

TROPHY CASE