Subject: Re: Disk format Path: lobby!newstf02.news.aol.com!portc04.blue.aol.com!newsfeed.wli.net!newsfeed.berkeley.edu!cyclone.swbell.net!typhoon01.swbell.net.POSTED!not-for-mail Message-ID: <36C235CB.71C9538B@swbell.net> From: Rubywand Reply-To: rubywand@swbell.net X-Mailer: Mozilla 4.5 [en] (Win95; U) X-Accept-Language: en MIME-Version: 1.0 Newsgroups: comp.sys.apple2,comp.sys.apple2.programmer References: <79sue8$ad6$1@platane.wanadoo.fr> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 44 Date: Wed, 10 Feb 1999 19:43:39 -0600 NNTP-Posting-Host: 207.193.12.56 X-Complaints-To: abuse@swbell.net X-Trace: typhoon01.swbell.net 918697403 207.193.12.56 (Wed, 10 Feb 1999 17:43:23 PDT) NNTP-Posting-Date: Wed, 10 Feb 1999 17:43:23 PDT Organization: SBC Internet Services Xref: lobby comp.sys.apple2:79589 comp.sys.apple2.programmer:9184 David Wilson writes ... > > "Aurelien Mere" writes: > >Does anybody know the disk format of 3"5 apple II disks ? > >I mean : number of sectors, tracks, bytes/sectors, heads, etc... > > It is the same (well almost) as the Mac: > > 80 tracks > 2 heads > 512 bytes/sector (Mac has extra 12 bytes for flags, Apple // has zeros) > Variable number of sectors per track > > For a single sided disk: > > Tracks Sectors/Track Sector #s > 0-15 12 0-191 > 16-31 11 192-367 > 32-47 10 368-527 > 48-63 9 528-671 > 64-79 8 672-799 > > I assume that for a double sided disk you just double the sector numbers. > Yes. For 2 sides, a 512-byte sector is usually called a "block" and the numbering of blocks alternates between the sides for each Track. For example ... Track 0, Side 1 has blocks 0-11 (decimal) Track 0, Side 2 has blocks 12-23 (decimal) So, you end up with ... Tracks Blocks/Track Block Numbers 0-15 12/side= 24 0-383 (decimal) ... 64-79 8/side= 16 1344-1599 (decimal) Rubywand