FT-DOS disk size

This is the best place to discuss about the various Oric operating systems like Sedoric, Randos, FT-Dos, and others.
Post Reply
User avatar
Symoon
Archivist
Posts: 1105
Joined: Sat Jan 14, 2006 12:44 am
Location: Paris, France
Contact:

FT-DOS disk size

Post by Symoon » Sat Apr 22, 2017 6:20 pm

Hi all,
I'm trying to write FT-DOS on a real 3" disk for someone that bought a Jasmin drive, but I keep having write errors after a while.

I noticed the DSK file is 513Kb big. Isn't it too much for a 3" disk?
Or is it just my real disks, or drive, that are getting old?

christian
Officer Cadet
Posts: 50
Joined: Sun Nov 24, 2013 9:58 pm

Re: FT-DOS disk size

Post by christian » Sat Apr 22, 2017 9:21 pm

Hi,

The usable size is 256 bytes * 17 sectors * 41 Tracks * 2 sides = 356 864 bytes.

But, a MFM_DISK image use 256 bytes for the header and 6400 bytes per track instead of 17*256 = 4352.
256 + 6400 * 41 *2 = 525 056 bytes or about 513Ko

User avatar
Symoon
Archivist
Posts: 1105
Joined: Sat Jan 14, 2006 12:44 am
Location: Paris, France
Contact:

Re: FT-DOS disk size

Post by Symoon » Sat Apr 22, 2017 9:42 pm

Ah, thanks a lot for this! Brillant explanation. So it should be fine, I'll keep trying with other disks...

BTW I tried to test the faulty disk with my Jasmin 2 but it began smoking after 30 seconds of unsuccessful attempts to boot... :cry:
I really know why I prefer tapes ;)

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest