April 3, 2026
When nostalgia boots to drama
DCJ11Hack+ – DEC PDP/11 based homebrew computer
Retro fans lose it over DIY PDP-11 build: “That chip is gorgeous” vs “Where are the bytes”
TLDR: A hobbyist released a DIY computer using a vintage PDP‑11 chip, sharing open schematics and code and moving the project to Codeberg. Comments love the craftsmanship but brawl over missing byte support, the old-school debug mode, and the GitHub exit—proof retro DIY is thriving and spicy.
Retrocomputing just lit up: maker Paula Maddox dropped her hand-built PDP‑11-inspired computer, based on the shiny DEC DCJ11 chip, and the comments immediately went full time machine. She posted the schematics, code, and PAL files on her site maddoxp.pro, crediting Beent Hilpert’s work and even linking the eBay backplane. Fans swooned over the chip’s look—memes dubbed it “silicon cheesecake”—and cheered the demo programs, from a “Hello, World” to the classic Knight Rider/Cylon light show.
Then came the drama. It boots into ODT, a built‑in command mode for poking around memory, instead of auto‑running code. Purists demanded “real” operating systems; tinkerers shouted back that ODT is the whole point. The biggest food fight: this board only reads and writes 16‑bit “words.” Byte writes? They’ll trash memory. One side called it a fatal flaw; the other called it a smart simplification for a hobby build. Jokes flew—“Wordle‑only RAM” trended—and someone insisted the write‑only text display is “the most vintage thing ever.”
And yes, there’s platform politics: the project moved from GitHub to Codeberg, sparking cheers from open‑source loyalists and groans from convenience crowd who “won’t make another account.” Through it all, Paula’s openness—down to PAL (programmable logic) files and a clear memory map—won major respect, while the eBay backplane listing reportedly braced for a stampede.
Key Points
- •Paula Maddox released schematics, PCB designs (KiCad), and PAL files for a modular DCJ11 (PDP‑11) homebrew computer.
- •The system comprises a CPU board and a combined RAM/ROM/text display board designed for a backplane.
- •On boot, the machine enters ODT mode; serial defaults are 115200 8N1 for console interaction.
- •A defined memory map allocates 32K RAM, 16K ROM, a write-only text display, a matrix display region, and future expansion space.
- •Code examples and workflow include using a PDP‑11 simulator, Tera Term uploads with 10 ms delays, and a 16‑bit word-only memory access constraint.