Path: news1.icaen!news.uiowa.edu!NewsNG.Chicago.Qual.Net!207.24.245.130!nyd.news.ans.net!news.idt.net!newspeer.monmouth.com!intgwpad.nntp.telstra.net!news1.optus.net.au!optus!news.usyd.edu.au!news.uow.edu.au!david From: david@uow.edu.au (David Wilson) Newsgroups: comp.sys.apple2 Subject: Re: Apple2 disk controller questions Date: 12 May 99 22:29:05 GMT Organization: University of Wollongong, Australia Lines: 89 Message-ID: References: <7h9d7i$f3k$1@news.cict.fr> <19990512013929.16539.00000804@ng-fz1.aol.com> <7hb9gl$dkg$1@news.cict.fr> <19990512044938.14706.00000065@ng-fk1.aol.com> <1drq2mt.3ynral1xmdhteN@dempson.actrix.gen.nz> NNTP-Posting-Host: wraith.cs.uow.edu.au X-Trace: wyrm.its.uow.edu.au 926549297 10604 130.130.64.1 (12 May 1999 22:48:17 GMT) X-Complaints-To: usenet@wyrm.its.uow.edu.au NNTP-Posting-Date: 12 May 1999 22:48:17 GMT X-Newsreader: NN version 6.5.0 #15 (NOV) Xref: news1.icaen comp.sys.apple2:147680 dempson@actrix.gen.nz (David Empson) writes: >Allow me to step up on the soapbox for a few minutes. >First: rotation speed and capacity issues. First, thank you for your extremely good description of disk formats. You saved me the trouble of researching the numbers an posting my own (less detailed) report. >(An aside: the high density 5.25" drive doubles the track density as >well as almost doubling the number of bits that can be recorded per >track. The high density 3.5" drive has the same track density as the >double density drive, probably to allow better compatibility with double >density media than you typically get with 5.25" drives.) High Density (1.2MB) 5.25" disks are a little different. They run at 500kb/s and at 360 rpm (which incidently is the rotation speed of 8" floppies). The PC/AT could read DD disks in its HD drive by changing the data rate to 300kb/s Here is a table of floppy disk formats I have built up over the years (I must add 21MB and 120MB floptical drives and Sony's HiFD drive soon): disk speed data rate trk sector trk/hd size rpm s/rev kb/s scheme kb cnt*sz count KB -------------------------------------------------------------------------------- 8" 360 0.167 500 FM 41.67 26*128 77/1 260 SSSD (8) 8" 360 0.167 500 FM 41.67 26*128 77/2 520 DSSD (8) 8" 360 0.167 500 MFM 83.33 26*256 77/1 520 SSDD (9) 8" 360 0.167 500 MFM 83.33 26*256 77/2 1040 DSDD (9) 5.25" 300 0.200 250 FM 25.00 8*256 40/1 80 SSSD 5.25" 300 0.200 250 FM 25.00 8*256 40/2 160 DSSD 5.25" 300 0.200 245 GCR 49.00 16*256 35/1 140 SSDD (1) 5.25" 300 0.200 250 MFM 50.00 8*512 40/1 160 SSDD (3) 5.25" 300 0.200 250 MFM 50.00 9*512 40/1 180 SSDD (3) 5.25" 300 0.200 250 MFM 50.00 8*512 40/2 320 DSDD (3) 5.25" 300 0.200 250 MFM 50.00 9*512 40/2 360 DSDD (3) 5.25" 300 0.200 250 MFM 50.00 9*512 80/2 720 DSDD 5.25" 360 0.200 300 MFM 50.00 9*512 40/2 360 DSDD (4) 5.25" 360 0.200 300 MFM 50.00 9*512 80/2 720 DSDD 5.25" 360 0.167 500 MFM 83.33 15*512 80/2 1200 DSHD (4) 3.5" 300 0.167 250 MFM 50.00 9*512 80/2 720 DSDD (5) 3.5" 300 0.167 250 MFM 50.00 5*1024 80/2 800 DSDD (2) 3.5" var var var GCR var var*512 80/2 800 DSDD (7) 3.5" 300 0.167 500 MFM 100.00 18*512 80/2 1440 DSHD (6) 3.5" var var var GCR var var*512 80/2 1600 DSHD (A) 3.5" 300 0.167 1000 MFM 200.00 36*512 80/2 2880 DSED (1) Apple ][ (2) Applix (3) IBM PC (4) IBM PC/AT (5) IBM PS/2 25,30 (6) IBM PS/2 > 30 (7) Macintosh & Apple // (8) IBM 3740 (9) IBM System 34 (A) AE 1.6MB drive on Apple // IBM System 34 format 256 byte sectors 12 * 00 3 * F5 1 * FE 1 * Track# 1 * Side# 1 * Sector# 1 * SecLen 2 * CRC 22 * 4E 12 * 00 3 * F5 1 * FB 256 * data 2 * CRC 54 * 4E ------ 372 bytes = 2976 bits -- David Wilson School of IT & CS, Uni of Wollongong, Australia david@uow.edu.au Path: news1.icaen!news.uiowa.edu!uunet!ffx.uu.net!news1.optus.net.au!optus!news.usyd.edu.au!news.uow.edu.au!david From: david@uow.edu.au (David Wilson) Newsgroups: comp.sys.apple2 Subject: Re: Apple2 disk controller questions 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 X-Trace: wyrm.its.uow.edu.au 926649404 5510 130.130.64.1 (14 May 1999 02:36:44 GMT) X-Complaints-To: usenet@wyrm.its.uow.edu.au NNTP-Posting-Date: 14 May 1999 02:36:44 GMT X-Newsreader: NN version 6.5.0 #15 (NOV) Xref: news1.icaen comp.sys.apple2:147714 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 Path: news1.icaen!news.uiowa.edu!NewsNG.Chicago.Qual.Net!207.24.245.130!nyd.news.ans.net!cloudbreak.rs.itd.umich.edu!sunqbc.risq.qc.ca!news.uow.edu.au!david From: david@uow.edu.au (David Wilson) Newsgroups: comp.sys.apple2 Subject: Re: Apple2 disk controller questions Date: 16 May 99 01:35:57 GMT Organization: University of Wollongong, Australia Lines: 15 Message-ID: References: <7h9d7i$f3k$1@news.cict.fr> <19990512013929.16539.00000804@ng-fz1.aol.com> <7hb9gl$dkg$1@news.cict.fr> <19990512044938.14706.00000065@ng-fk1.aol.com> <1drq2mt.3ynral1xmdhteN@dempson.actrix.gen.nz> NNTP-Posting-Host: wraith.cs.uow.edu.au X-Trace: wyrm.its.uow.edu.au 926818775 22460 130.130.64.1 (16 May 1999 01:39:35 GMT) X-Complaints-To: usenet@wyrm.its.uow.edu.au NNTP-Posting-Date: 16 May 1999 01:39:35 GMT X-Newsreader: NN version 6.5.0 #15 (NOV) Xref: news1.icaen comp.sys.apple2:147769 No one has pointed out the error I made in my table for the Apple Disk ][ specs. david@uow.edu.au (David Wilson) writes: >5.25" 300 0.200 245 GCR 49.00 16*256 35/1 140 SSDD (1) This should actually read: 5.25" 300 0.200 ~255 GCR ~51 16*256 35/1 140 SSDD (1) This is because the 65(c)02 rus at slightly more than 1MHz, not less. The PAL Apple // actually runs a tad slower and writes disks at approx 254 kb/s. -- David Wilson School of IT & CS, Uni of Wollongong, Australia david@uow.edu.au