aceverj@accucx.cc.ruu.nl (Jaap Verhage) (05/29/90)
In article <2381@zipeecs.umich.edu> shim@zip.eecs.umich.edu (Sam Shim) writes: > > A while back, I posted a message stating that DOS has a 32 Meg limit due to >the fact that the sectors are mapped in the FAT, and that the FAT has room >for only 65,535 entries (65,535 x 512 bytes = the 32 Meg limit). This is >wrong. The reason for the 32 Meg limit is because with 2 byte sector >addressing and 512 bytes per sector, DOS can only access 32 Megs of sectors. >The FAT is a map of CLUSTERS, and not sectors, so theoretically, the FAT >can map up to 130 Megabytes. Thanks to John Nelson for pointing out the >error. > Yes, all of this may be true, but the 32 Mb limit has disappeared with DOS 4.0. I don't know what the limit is now, but it's certainly more than it was.
kperson@plains.UUCP (Kerry Person) (05/29/90)
In article <446@accucx.cc.ruu.nl> aceverj@accucx.UUCP (Jaap Verhage) writes: >> >Yes, all of this may be true, but the 32 Mb limit has >disappeared with DOS 4.0. I don't know what the limit is now, >but it's certainly more than it was. I thought it was the square of the previous limit, since the address now has twice as many digits. Or am I all wet? Kerry Person (kperson@plains.NoDak.edu)
dmurdoch@watstat.uwaterloo.ca (Duncan Murdoch) (05/29/90)
In article <4915@plains.UUCP> kperson@plains.UUCP (Kerry Person) writes: >In article <446@accucx.cc.ruu.nl> aceverj@accucx.UUCP (Jaap Verhage) writes: >>> >>Yes, all of this may be true, but the 32 Mb limit has >>disappeared with DOS 4.0. I don't know what the limit is now, >>but it's certainly more than it was. > > >I thought it was the square of the previous limit, since the address now has >twice as many digits. Or am I all wet? It's not quite the square - other things get in the way. It used to be that 64K of sectors limited your disk to 32 Megs. Now there's effectively no limit on the number of sectors, but there's still a limit of 64K (minus some special codes) on the number of clusters. This means that you can't go bigger than 128 Meg with 2K clusters, 256 Meg with 4K, etc. I don't know the largest cluster size DOS 4 can handle, but I doubt you'd want the 32 megabyte clusters on a disk with (64K)**2 sectors. (On the other hand, on a 2 terabyte disk, it might not matter.) By the way, does anyone know a reliable test for whether a particular copy of DOS can handle/requires the new long sector numbers in absolute read and write? Zenith DOS 3.30 Plus can and does on big disks, but just about every other 3.30 (which all look identical if you just ask for a version number) can't. I think it's safe to say that any version 3.31 or higher can use the new calls; is this true? Duncan Murdoch
tea6219@evtprp0b.UUCP (Terry E. Acker) (05/30/90)
In article <446@accucx.cc.ruu.nl> aceverj@accucx.UUCP (Jaap Verhage) writes: >Yes, all of this may be true, but the 32 Mb limit has >disappeared with DOS 4.0. I don't know what the limit is now, >but it's certainly more than it was. The limit with DOS 4.0 is 2G. Also, I know that Compaq DOS 3.31 has the ability to have partitions up to 512Mb. I am currently using Compaq DOS 3.31 with a 40Mg Microscience with no problems whatsoever.
cgordon@vpnet.chi.il.us (Gordon Hlavenka) (05/31/90)
>...but I doubt you'd want the >32 megabyte clusters on a disk with (64K)**2 sectors. (On the other hand, >on a 2 terabyte disk, it might not matter.) But this would pretty much eliminate file fragmentation... Gordon S. Hlavenka cgordon@vpnet.chi.il.us DISCLAIMER: He's lying.
pnl@hpfinote.HP.COM (Peter Lim) (05/31/90)
> > I thought it was the square of the previous limit, since the address now has > twice as many digits. Or am I all wet? > You are all wet :-). Previously the limit was 32 MB and now it is 512 MB (and 32 MB squared is a lot bigger than 512 MB). That's all I konw about DOS 4.0. --- I never use it. > Kerry Person > (kperson@plains.NoDak.edu) > ---------- Regards, ## Life is fast enough as it is ........ Peter Lim. ## .... DON'T PUSH IT !! >>>-------, ########################################### : E-mail: plim@hpsgwg.HP.COM Snail-mail: Hewlett Packard Singapore, : Tel: (065)-279-2289 (ICDS, ICS) | Telnet: 520-2289 1150 Depot Road, __\@/__ ... also at: pnl@hpfipnl.HP.COM Singapore 0410. SPLAT !
kperson@plains.UUCP (Kerry Person) (05/31/90)
In article <19450060@hpfinote.HP.COM> pnl@hpfinote.HP.COM (Peter Lim) writes: >> >You are all wet :-). Previously the limit was 32 MB and now it is >512 MB (and 32 MB squared is a lot bigger than 512 MB). That's all I >konw about DOS 4.0. --- I never use it. > > >Regards, ## Life is fast enough as it is ........ > Whoa, now! Are we sure about this? I thought it was at least in the Gig's! 512 MB sounds way too small. Seems I remember it was either 2 or 4 GB. Kerry Person (kperson@plains.NoDak.edu)
kdq@demott.COM (Kevin D. Quitt) (06/01/90)
In article <4933@plains.UUCP> kperson@plains.UUCP (Kerry Person) writes: >In article <19450060@hpfinote.HP.COM> pnl@hpfinote.HP.COM (Peter Lim) writes: >>> >>You are all wet :-). Previously the limit was 32 MB and now it is >>512 MB (and 32 MB squared is a lot bigger than 512 MB). That's all I >>konw about DOS 4.0. --- I never use it. >> >> >>Regards, ## Life is fast enough as it is ........ >> > >Whoa, now! Are we sure about this? I thought it was at least in the Gig's! >512 MB sounds way too small. Seems I remember it was either 2 or 4 GB. > (Note: the following is not a flame of the above persons). Who cares? Most of my files, and I suspect yours, are farily small, with a couple of large ones thrown in. Back in the bad old days when clusters were 4K, I found a way to force them to 2K, and gained 30% of my disk back. What would be useful would be to have more clusters, not larger clusters. The latter just waste space and fool you into thinking you've got a lot more storage than you actually do. -- _ Kevin D. Quitt Manager, Software Development 34 12 N 118 27 W DeMott Electronics Co. 14707 Keswick St. Van Nuys, CA 91405-1266 VOICE (818) 988-4975 FAX (818) 997-1190 MODEM (818) 997-4496 Telebit PEP last demott!kdq kdq@demott.com 96.37% of the statistics used in arguments are made up.
dlow@hpspcoi.HP.COM (Danny Low) (06/01/90)
>Whoa, now! Are we sure about this? I thought it was at least in the Gig's! >512 MB sounds way too small. Seems I remember it was either 2 or 4 GB. >Kerry Person There is a limit in the BIOS that limits disk size to about 512MB. This lower BIOS limit overrides the higher DOS 4.01 limit. Danny Low "Question Authority and the Authorities will question You" Valley of Hearts Delight, Silicon Valley HP SPCD dlow%hpspcoi@hplabs.hp.com ...!hplabs!hpspcoi!dlow
marshall@wind55.seri.gov (Marshall L. Buhl) (06/02/90)
To quote my Dell MS-DOS User's Reference manual in the section on the FDISK command: "If you want to use the entire hard disk (up to 2 gigabytes) for MS-DOS, press the ENTER key to accept the default selection (Y)." -- Marshall L. Buhl, Jr. EMAIL: marshall@seri.gov Senior Computer Engineer VOICE: (303)231-1014 Wind Research Branch 1617 Cole Blvd., Golden, CO 80401-3393 Solar Energy Research Institute Solar - safe energy for a healthy future
dlow@hpspcoi.HP.COM (Danny Low) (06/02/90)
>To quote my Dell MS-DOS User's Reference manual in the section on the >FDISK command: > > "If you want to use the entire hard disk (up to 2 gigabytes) for > MS-DOS, press the ENTER key to accept the default selection (Y)." If you have a hard disk greater than 528,482,304 bytes, try writing beyond that with INT 13H Function 0BH (Write disk). If your BIOS is IBM compatible, it will not allow you to do this. You need an non-BIOS hard disk driver to write beyond the 528MB limit or have a BIOS that is not IBM compatible. Danny Low "Question Authority and the Authorities will question You" Valley of Hearts Delight, Silicon Valley HP SPCD dlow%hpspcoi@hplabs.hp.com ...!hplabs!hpspcoi!dlow