The silicon is on the copper. Every mux on one board, both adders, the first lamps of the debug wall. Held next to the sim, the slice finally looks like the machine that was designed.

Read the dispatch →

The delayed order, replaced on the phone, then on the cobbles. After weeks of schematics, the chips are a box you can hold.

Desk cleared. Flux, tweezers, iron, meter. An SMD footprint is a different object in the hand than on a grid.

Tweezers, iron, one SOIC at a time. The dual-LUT plane is no longer a schematic symbol.

The indicators are tiny. Align, don’t bridge, repeat. Seven on the wall so far.

The PCBs all just arrived — five of them. I tested power with a continuity meter and logged no islands. It is beautiful watching a board of such sophisticated nature, realizing I remember placing every single trace.

Now the soldering begins. Read the dispatch →

As received on the desk — silk reads Tomato ALU 8 bit, July 2026. Five identical slices from the same panel run.

A slow pass over the stack — mask colour, edge plating, and the LED wall footprint visible before population.

First bring-up step: continuity on VCC and GND across every board. Clean on all five — no open pours, no shorted islands from fab.

KiCad 3D before fab — two alu_4b nibble cells chained on CIN-MAIN, with the flag block and opcode lamp wall for bench debug.

Fab-ready top layer — 308 vias, 2404 segments, every net closed before the order went out.

The predecessor on alu.tmarhguy.com — discrete MOSFETs where 07_alu now packs dual-LUT logic into 74xx copper.

Schematic tree mirrors Digital simulation — the hierarchy on the sheet matches the verification ladder from 1b through 8b.

The front-page orbit — paper-stock lighting on the real mask colour. Same model as the interactive bench on Orbit.

Swapped in when the paper runs Black — the same slice under low studio light, copper catching the key.

Brute-force sweep in Digital — the AND3 family surfaces at opcode 0x80 before the same vector is replayed on silicon.

Same sweep on hardware — the FPGA clip confirms the sim hit before copper is populated.

The iron is on the desk. Boards and DigiKey parts inbound. Dispatch →

Five boards under six dollars — cheap enough to spin again if the fab errs.

25 logic ICs per 8-bit slice — the 74ACT family that replaces discrete transistors on 07_alu.