Tuesday, March 23, 2010

Linux as a Serial Terminal; Revenge of the Floppi

I'm thinking it's time to upgrade the operating system in my PC Engines WRAP boxlet, which I use as a DMZ (of sorts) between my home boxen and the ADSL modem, or "home router". The WRAP, of course, has no keyboard, no mouse, and no monitor. Other than Ethernet, the only way it communicates with the outside world is via a serial port. So, for testing I'm going to need some kind of serial terminal.

This placed me in a predicament of sorts, because all of the computers with serial ports around here were junked long ago. Except for one... old Dell laptop that I had been using as a doorstop. When I took the battery out, I was able to power it up and even boot MS-DOS from a floppy. On the net I found this HOWTO:

Linux as a serial terminal

The HOWTO calls for a floppy disk to be created with a minimalist Linux system on it, to serve as a "dumb" serial terminal. Simple enough, I thought - there's even a floppy image for download, so you don't have to roll your own. I downloaded the floppy image to my Ubuntu machine, installed a floppy drive, and issued the command fdformat /dev/fd0

No go on the first diskette. I proceeded to try about 30 more, but none of them worked. At first I thought I'd have to buy some new diskettes, but then I poked around some on Google and discovered that there's a bug in later 2.6.x kernels (from around 2.6.28, but I reproduced it in 2.6.24 off a live CD) that makes it impossible to low-level format a floppy disk. What a joy!

After I got "Linux as a serial terminal" onto a floppy, the old Dell laptop booted right up into microcom. However, I haven't had time yet to test it with the WRAP.

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