Subject: Re: Apple2 disk controller questions From: david@uow.edu.au (David Wilson) Newsgroups: comp.sys.apple2 Date: 14 May 99 02:32:36 GMT Organization: University of Wollongong, Australia Lines: 38 Message-ID: References: <19990513022148.00956.00001254@ng38.aol.com> NNTP-Posting-Host: wraith.cs.uow.edu.au supertimer@aol.com (Supertimer) writes: >Wow! Ok, next question: how does the Amiga fit 880k into a DS/DD 3.5" disk? From http://www.blizzard.u-net.com/expand/floppy.html: As well as the internal DF0: drive, the Amiga can have upto 3 external drives (DF1-DF3). The Amiga normally uses Double Density drive (880k) but can used specially made High Density drive (1.76Mb). The Amiga differs from PC made drives in a number of ways: Paula custom chip controls the floppy drives and uses non-standard 11 sectors/track format (PCs use 9 sectors/track and is the reason why it is impossible for them to read Amiga disks), uses a disk-detection system when disks are inserted/removed and a non-standard interface. Paula cannot cope with high density drives at full speed and moved be slowed down to read/write high density disks. This explains why Amiga HD drives are much more expensive. In place of a floppy drive it is possible to replace it with a 2nd hard drive or even a Zip drive! Suppliers: Analogic Computers, Marpet Developments, EyeTech, First Computer Centre, Power Computing and many more! So to add to my table: 3.5" 300 0.167 250? MFM? 50.00? 11*512 80/2 880 DSDD (B) 3.5" 300 0.167 500? MFM? 100.00? 22*512 80/2 1760 DSHD (C) (B) Amiga DD (C) Amiga HD (guessing about the 22 sectors) I am assuming that standard bit rates are used but this may not be the case (in order to fit the extra sectors) Then there is Microsoft's Distribution Format which fits more than 1440KB on a DS/HD 3.5" disk. -- David Wilson School of IT & CS, Uni of Wollongong, Australia david@uow.edu.au