updated 17 feb 2020
Feb 2020 note: obviously today you'd just use a Raspberry Pi and everything would be easy. In 2006 when I started this storage was mechanical hard disks, the only configurable hardware that could run linux was "desktop" motherboards, etc. Power supplies were tricky. A lot changed in 10 years.
The software bundle, which includes linux config, runtime scripts, perl script for the player, and C code for the Arduino control head, is here: Music computer for 70 Hornet.zip. Uncompressed it's 35 MB or so. This also includes a simple wifi "war driver", it worked pretty well at snarfing wifi driving down a freeway. It kept SSID lists, and I realized if I cached last-assigned DHCP IP, I could probably cheat it.
(2009 note: I abandoned this project after three years of work; the software and hardware worked great, but the power supplies kept popping and at $100 each, it was too much. They're clearly not designed to deal with the load dumps caused by older American cars. I assume they test on little Hondas and the like.)
To be blunt modern car stereos are not only crap, they're a total rip-off. Like sheep, buyers flock to flashy displays, somehow ignoring how terrible they perform: lousy controls (pushbuttons for volume up and down? Are they mad?), a few useful functions buried under excessive modality, bristling with useless features (the same old "tone controls" tied to memory settings and sold to you as "profiles"), plus they're delicate, expensive, attract ruinous dim-witted thieves, and the bottom line, they don't really sound any better than good car stereos did 20 years ago. (Switcher power supply tech at least means you can get 20 watts RMS per channel though.) And to add insult, the old "music power" rating lies are back -- "240 peak watts!" is intentionally deceitful.
I decided to do something about this and design a trivial-to-use (but unfortunately not to build), absolutely unflashy but solidly functional sound system for my 1970 AMC Hornet. Four speakers plus subwoofer, 25 watts RMS driving each (hearing-loss capable!), our collective entire music collection (about 400 CDs ripped so far) available with one hand while driving, no "removeable front panel" nonsense, and looks like it belongs in a 36-year-old car.
There is no way to rip music CDs in the car; this is intentional. With enough storage for my entire music collection, what's the point? When I get a new CD, I rip it at home, and it's automagically copied into the car via the internet. I've have had problems with wifi networking, which is why it's been absent from this page; see below for details.
Whether you like my system or not, I have very specific criteria for what it should do and how it should "feel", a lot of which is intentionally counter to car electronics fashion. Read, in order, before you complain or ask questions: