keithd@cadovax.UUCP (05/16/87)
In article <18746@sun.uucp> cmcmanis@sun.uucp (Chuck McManis) writes: >Another note : Most computers like the Atari and IBM use dedicated floppy >disk controllers that work on a sector by sector basis. These computers >leave gaps between the sectors to allow for variations in disk speed, and >before the sector, usually write a 'sync' pattern that locks the controllers >phase locked loop onto the data stream. Since the Amiga writes entire tracks >it can eliminate those gaps and use the recoverd space for data. That >results in the 'extra' 80K of space/disk or one 512 byte sector/track. Anybody have any idea how the new IBM PS/2 line gets 1.4 meg on 3 1/2 inch floppy? sounds like 720k a side. Keith Doyle # {ucbvax,ihnp4,decvax}!trwrb!cadovax!keithd # cadovax!keithd@ucla-locus.arpa Contel Business Systems 213-323-8170
yuan@uhccux.UUCP (Yuan Chang) (05/17/87)
In article <1542@cadovax.UUCP> keithd@cadovax.UUCP (Keith Doyle) writes: >Anybody have any idea how the new IBM PS/2 line gets 1.4 meg on 3 1/2 inch >floppy? sounds like 720k a side. It simply uses more tracks per side (160 tracks, versus 80 track/surface on the Amiga). Yes, it is 720K/side. -- UUCP: {ihnp4,seismo,ucbvax,dcdwest}!sdcsvax!nosc!uhccux!yuan ARPA: uhccux!yuan@nosc.MIL INTERNET: yuan@UHCC.HAWAII.EDU AT&T: (808) 395-1732 "I'm an Amigoid, she's an Amigoid, they're Amigoids, - Yuan Chang - Wouldn't _y_o_u like to be an Amigoid too?"
cmcmanis@sun.uucp (Chuck McManis) (05/18/87)
In article <494@uhccux.UUCP>, yuan@uhccux.UUCP (Yuan Chang) writes: $ In article <1542@cadovax.UUCP> keithd@cadovax.UUCP (Keith Doyle) writes: $ >Anybody have any idea how the new IBM PS/2 line gets 1.4 meg on 3 1/2 inch $ >floppy? sounds like 720k a side. $ $ It simply uses more tracks per side (160 tracks, versus 80 track/surface $ on the Amiga). Yes, it is 720K/side. $ - Yuan Chang - Not likely, I bet they did it the exact same way they got 1.2Meg on an AT floppy which is to say a 500Khz data clock. That lets 'em cram 9 1K sectors per track and with 80 tracks/side they get 1440 K of storage. The Amiga stores 11 512 byte sectors per track and use 160 tracks and gets 880 K. The difference is in the data clock rate. The Amiga uses a 5.25" disk compatible 250Khz data clock. -- --Chuck McManis uucp: {anywhere}!sun!cmcmanis BIX: cmcmanis ARPAnet: cmcmanis@sun.com These opinions are my own and no one elses. But you knew that, didn't you.
bmarsh@cod.UUCP (William C. Marsh) (05/19/87)
In article <494@uhccux.UUCP> yuan@uhccux.UUCP (Yuan Chang) writes: >In article <1542@cadovax.UUCP> keithd@cadovax.UUCP (Keith Doyle) writes: >>Anybody have any idea how the new IBM PS/2 line gets 1.4 meg on 3 1/2 inch >>floppy? sounds like 720k a side. > > It simply uses more tracks per side (160 tracks, versus 80 track/surface >on the Amiga). Yes, it is 720K/side. > According to the DOS 3.3 Technical Reference Manual (which IBM sent to me for some unknown reason) the two 'formats' for 3.5" media are as follows: Sides Sectors/Track Media Descriptor 2 9 F9H 2 18 F0H It looks like they put twice the number of sectors on the little disk, instead of twice the number of tracks. That means there won't be any "I can't write 720K disks in my 1.4M drive" problems like with the 1.2M drives in the AT. What, IBM learning from their mistakes? Maybe someday they will come out with a keyboard where you don't want to swap at least two keys... ---------- Bill Marsh, Naval Ocean Systems Center, San Diego, CA {arpa,mil}net: bmarsh@cod.nosc.mil uucp: {ihnp4,akgua,decvax,dcdwest,ucbvax}!sdcsvax!nosc!bmarsh "If everything seems to be coming your way, you're probably in the wrong lane."
keithd@cadovax.UUCP (05/20/87)
In article <494@uhccux.UUCP> yuan@uhccux.UUCP (Yuan Chang) writes: >In article <1542@cadovax.UUCP> keithd@cadovax.UUCP (Keith Doyle) writes: >>Anybody have any idea how the new IBM PS/2 line gets 1.4 meg on 3 1/2 inch >>floppy? sounds like 720k a side. > > It simply uses more tracks per side (160 tracks, versus 80 track/surface >on the Amiga). Yes, it is 720K/side. Oh YEAH? How compatible are the drives (including mounts)? Anybody know what's the possibility of getting a couple of drives, and with some driver hacks upgrading an Amiga to use them? Keith Doyle # {ucbvax,ihnp4,decvax}!trwrb!cadovax!keithd # cadovax!keithd@ucla-locus.arpa Contel Business Systems 213-323-8170
grr@cbmvax.UUCP (05/20/87)
In article <1548@cadovax.UUCP> keithd@cadovax.UUCP (Keith Doyle) writes: > In article <494@uhccux.UUCP> yuan@uhccux.UUCP (Yuan Chang) writes: > >In article <1542@cadovax.UUCP> keithd@cadovax.UUCP (Keith Doyle) writes: > >>Anybody have any idea how the new IBM PS/2 line gets 1.4 meg on 3 1/2 inch > >>floppy? sounds like 720k a side. > > > > It simply uses more tracks per side (160 tracks, versus 80 track/surface > >on the Amiga). Yes, it is 720K/side. > > Oh YEAH? How compatible are the drives (including mounts)? Anybody know > what's the possibility of getting a couple of drives, and with some driver > hacks upgrading an Amiga to use them? They're double bit density, not double the number of tracks. The built-in floppy disk controller can't handle MFM formats at the 500 K bits/sec rate used by these drives, 8" DD floppys or the AT 1.2 MB format. Apple type GCR might work, but you'd have to write you own floppy driver to test it out. -- George Robbins - now working for, uucp: {ihnp4|seismo|rutgers}!cbmvax!grr but no way officially representing arpa: cbmvax!grr@seismo.css.GOV Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)