Phillip Pearson - web + electronics notes

tech notes and web hackery from a new zealander who was vaguely useful on the web back in 2002 (see: python community server, the blogging ecosystem, the new zealand coffee review, the internet topic exchange).


Imaging old 3.5" floppy disks (DOS 720k, DOS 1.44M, ADFS 320k, ADFS 800k, DFS 100k, DFS 200k) in New Zealand using libdsk/dsktrans

Wow, it's been a while since I last posted. Since then I started working at Google, made a ton of hardware projects for the Acorn series of computers: Electron, BBC Micro, BBC Master, and have enjoyed a year and a half of marriage.

I spent a week in New Zealand visiting family for Christmas. My main project while there was to clean up a whole lot of stuff I left behind when I moved to the USA, which, among a whole lot of physical stuff like university notes, included various hard disks, and several hundred floppy disks in various formats. Most of them were 1.44M DOS disks, but the most interesting ones (because I was hoping to find traces of the earliest programs I'd written, in the 80s) were in various Acorn formats like 320k ADFS and 200k DFS, as well as the newer 800k and 1.6M ADFS.

Luckily it appears that the last desktop computer I bought, an Athlon XP machine from 2005, was capable of reading *all* the formats. As confirmed by Andrew Benham in London, the libdsk project and its dsktrans tool work really well and can autodetect all the formats I was interested in.

Healthy disks could be copied quickly with: dsktrans /dev/fd0 image.dsk

Disks with errors required: dsktrans -retry 10 -stubborn /dev/fd0 image.dsk

I never needed to specify -format; I experimented a bit with some unknown disks, but it looks like the ones that dsktrans couldn't autodetect were unreadable using any of the formats I tried.

This results in .DSK format files, which contain the data from the sectors on the disk, but also quite a bit of metadata about the disk, and can be converted into raw images suitable for reading in emulators by running them through dsktrans again:

For DOS disks, which macOS will happily open if given .dmg extensions: dsktrans image.dsk -otype raw image.dmg

For ADFS disks: dsktrans image.dsk -otype logical image.adf

I assume the ADFS approach will also work for DFS, but either I haven't found an emulator that understands 3.5" DFS disks yet, or my disks were too damaged.