On Jan 18, 16:16, Philip Pemberton wrote: The way Acorn did that with things like the Master 128 Welcome Disc was to make all the directory entries (on track 0) point to tracks between 5 and 9, and 20 and 39. Track 20 on a 48-tpi drive is where track 40 would be on a 96-tpi drive: 96tpi 0 5 9 19 20 39 40 59 60 79 | | | | | | | D |X| |XXXXXXXXX| | | |__|_|____|_________|_________|_________| | | | | | | D |xxxx| |xxxxxxxxx|xxxxxxxxx| | | | | | | 48tpi 0 4 5 9 10 19 20 29 30 39 So you need to format parts of the disk as if they're 40-track and parts as if they're 80-track. Start by formatting the disk normally, at the density-of-your-choice. Next, write some dummy files that will occupy exactly tracks 0 (less the directory area) to 4, 5 to 9, and 9 to 19, and then delete the dummy that is in the space 9 to 19. You only need to do this for one density, thankfully, as the object is just to get the right placeholders in the space map. Then write the real data. Switch densities, format the tracks that need to be the alternate density (Disc Doctor can do this), and write the real files again. You may need to do the second set of writes with raw disk access, as IIRC ADFS will "overwrite" a file by writing a new version andf then deleting the old one -- which is not what you want because it will use the wrong space! -- Pete Peter Turnbull Network Manager University of York