Voyager FDS on a Chip

The computer that left the solar system. On SKY130 silicon.

The Voyager Flight Data Subsystem, placed on SkyWater SKY130 130nm silicon. Each coloured rectangle is a transistor. The green is polysilicon. The pink is metal1. The blue is nwell. The original filled a shoebox. This fits on a grain of sand.

What Is This

A synthesisable implementation of the Voyager Flight Data Subsystem (FDS) processor, the computer that flew on Voyager 1 and Voyager 2. Synthesised to SkyWater SKY130 130nm standard cells.

Gates	58 (after optimisation)
Area	4,793 µm²
Timing	Met at 1 MHz (original: 806.4 kHz)
Architecture	16-bit words, 13-bit PC, ALU with ADD/SUB/XOR/AND/OR
Source	JPL Memo MJS 2.64A (Wooddell, 7 October 1974)
Status	Still operating. 24 billion km away.

Files

• voyager_fds.sv — SystemVerilog source (the design)
• voyager_fds_sky130.v — SKY130 gate-level netlist
• voyager_fds.def — Placed layout (viewable in KLayout)
• sky130_fd_sc_hd.gds — SKY130 cell library GDS (for viewing)
• flow/ — OpenROAD scripts for place-and-route

Viewing the Layout

1. Install KLayout
2. Open sky130_fd_sc_hd.gds (cell library)
3. Open voyager_fds.def (placed design)
4. Zoom in. Those are the transistors of the computer that photographed Neptune.

Building

# Synthesise
takahe --lib sky130_fd_sc_hd__tt_025C_1v80.lib \
       --map voyager_fds_sky130.v \
       --sta 1 \
       voyager_fds.sv

# Place and route (Docker)
docker run -v $(pwd):/work openroad/orfs \
       bash /work/flow/clean_and_route.sh

Fabricate

Submit the layout to TinyTapeout for a SKY130 shuttle run. ~$150 for a tile. 12-16 weeks to silicon. The computer that went to Neptune, in your hand.

History

The FDS was designed by JPL engineers in the early 1970s. The architecture memo is dated October 7, 1974. Voyager 1 launched September 5, 1977. Voyager 2 launched August 20, 1977.

Both spacecraft are still operating. Voyager 1 has entered interstellar space. The FDS processes all science data: every photograph of Jupiter, every reading from Saturn's rings, every measurement of the heliopause.

It has been running for 48 years without a reboot. Your phone struggles to make it through the day.

We thought someone should be able to hold that computer in their hand.

Built With

Synthesised using Takahe, an open-source SystemVerilog/VHDL synthesiser. Placed via OpenROAD.

License

MIT. The instruction set is from a 1974 JPL memo (US government, public domain). The implementation is original.