If you're interested in learning more or porting a driver yourself, the following resources might be helpful:

• Existing drivers for Syllable: http://syllable.cvs.sourceforge.net/syllable/syllable/system/sys/kernel/drivers/ or from CVS syllable/syllable/system/sys/kernel/drivers
• The Syllable kernel documentation: http://development.syllable.org/documentation/index.html
• Linux, from http://www.kernel.org
• The BSD driver models are different, but may provide a source of inspiration:
  • FreeBSD
  • NetBSD
  • OpenBSD
• Linux Device Drivers by Alessandro Rubini & Jonathan Corbet is an excellent introduction to writing drivers. While it is aimed at Linux, many of the core concepts apply to Syllable. It is available from bookshops, or the 2nd edition is available free to download from http://www.xml.com/ldd/chapter/book/