emmonsl@athena.ecs.csus.edu (L. Scott Emmons) (11/30/90)
I am experiencing problems using absread() / abswrite() to access raw
(not-neccessarily-msdos) floppies. I am unable to read side 1 of
disks... reads walk down side 0 from track 0 to track 359 with no
problem (360K drives...); however the second side of the disk does not
seem to be accessible. It would seem to me that absread/abswrite could
reasonably try reading from other heads on the device (like after the
last track on side 0 or something). What's the point of this system
call, besides accessing single-sided devices ONLY? Guess I will have
to use biosdisk(), which I wanted to avoid...
Thanks,
Scott
L. Scott Emmons
---------------
emmonsl@csus.edu <or> ...[ucbvax]!ucdavis!csusac!athena!emmonsl
Packet: kc6nfp@kg6xx.#nocal.ca.usa.nadmurdoch@watstat.waterloo.edu (Duncan Murdoch) (11/30/90)
In article <1990Nov30.071240.8847@csusac.csus.edu> emmonsl@athena.ecs.csus.edu (L. Scott Emmons) writes: > >I am experiencing problems using absread() / abswrite() to access raw >(not-neccessarily-msdos) floppies. I am unable to read side 1 of >disks... reads walk down side 0 from track 0 to track 359 with no >problem (360K drives...); however the second side of the disk does not >seem to be accessible. It would seem to me that absread/abswrite could >reasonably try reading from other heads on the device (like after the >last track on side 0 or something). What's the point of this system >call, besides accessing single-sided devices ONLY? Guess I will have >to use biosdisk(), which I wanted to avoid... According to my manual, absread uses the DOS absolute read service. As far as that service is concerned, disks don't have sides: they're just a bunch of sectors, running from 0 to 719 on a standard 360K disk. If you can read sectors 0 to 359, you're reading both sides of the disk, tracks 0 to 19. You seem to be having trouble reading tracks 20 to 39, which is a completely different problem. Unless TC is really messed up (it's shelfware for me, so I have the manuals, but I don't really know how well it works), I'd suspect your problem is somewhere else. Perhaps something has happened to the boot sector of your disk, so DOS thinks it's single sided? Duncan Murdoch
valley@uchicago (Doug Dougherty) (11/30/90)
(If I understand the original posting correctly, he is trying to read non-msdos disks) Since absread() uses DOS, I doubt it could read non-DOS disks. Or am I missing something???
emmonsl@athena.ecs.csus.edu (L. Scott Emmons) (12/01/90)
In article <1990Nov30.141911.5076@maytag.waterloo.edu> dmurdoch@watstat.waterloo.edu (Duncan Murdoch) writes: >According to my manual, absread uses the DOS absolute read service. As >far as that service is concerned, disks don't have sides: they're just >a bunch of sectors, running from 0 to 719 on a standard 360K disk. If >you can read sectors 0 to 359, you're reading both sides of the disk, tracks >0 to 19. You seem to be having trouble reading tracks 20 to 39, which >is a completely different problem. I thought of this (reading a sector reads from both sides of a disk [i.e. a cylinder]), however calling absread with a 1K buffer (i.e. two sectors) didn't result in reading both sides of the disk. As it is an absolute read/write, it should _not_ know enough to read a track from side 2 after reading a track from side 1 (because to do that it would have to know the topological format of the disk, which it would get off the boot sector (or fat...wherever it is); but, this can't be since abs read/write should be independent of disk topology. Or, it could start with side 2 after reaching the end of side 1 (could be done w/o regard for topology), or (as you suggest and I tried) it could read full cylinders (problem with buffer size, though, as this is device dependant [i.e. the same routine would work only for devices with the same number of heads]). >I'd suspect your problem is somewhere else. Perhaps something has happened to >the boot sector of your disk, so DOS thinks it's single sided? It can't be this, because I am using diskettes with raw data (no boot sector, no fat: nothing but raw data); without regard to _ANY_ format, beyond a disk "oriented by cylinders, with 40 tracks, 2 sides, and 9 sectors per track". Thanks for your response, Scott L. Scott Emmons --------------- emmonsl@csus.edu <or> ...[ucbvax]!ucdavis!csusac!athena!emmonsl Packet: kc6nfp@kg6xx.#nocal.ca.usa.na
tjr@cbnewsc.att.com (thomas.j.roberts) (12/01/90)
From article <valley.659978709@gsbsun>, by valley@uchicago (Doug Dougherty): > (If I understand the original posting correctly, he is trying to read > non-msdos disks) Since absread() uses DOS, I doubt it could read > non-DOS disks. Or am I missing something??? Almost correct. TC absread/abswrite use the DOS functions to read DOS' idea of what the disk looks like. DOS reads (on a floppy) sector 0 to get the layout of the disk; sector 0 is correctly set up (on a floppy) by the DOS FORMAT command. You can use absread/abswrite on a non-DOS floppy, as long as sector 0 contains the proper BIOS Parameter Block in bytes 11-28 of sector 0; this might well prevent reading diskettes written by other operating systems. You can use absread/abswrite ONLY (i.e. no open/fopen) on sectors 1-up to abswrite directly to the disk, and absread it back again, without problems; you get no filenames, etc. On a hard disk, sector 0 contains the partition table (I think), and each partition contains its own BPB as on a floppy (values are different!). Tom Roberts att!ihlpl!tjrob TJROB@IHLPL.ATT.COM
emmonsl@athena.ecs.csus.edu (L. Scott Emmons) (12/01/90)
In article <1990Nov30.183106.29270@cbnewsc.att.com> tjr@cbnewsc.att.com (thomas.j.roberts) writes: >TC absread/abswrite use the DOS functions to read DOS' idea of what the >disk looks like. DOS reads (on a floppy) sector 0 to get the layout >of the disk; sector 0 is correctly set up (on a floppy) by the >DOS FORMAT command. You can use absread/abswrite on a non-DOS floppy, >as long as sector 0 contains the proper BIOS Parameter Block in bytes >11-28 of sector 0; this might well prevent reading diskettes written >by other operating systems. Ah ha! Thanks for this information; just the information I needed...I have since dropped using abs read/write and am using the biosdisk() call instead. non-msdos-formatted diskettes are now being read/written properly...all cylinders, all sectors, and all sides...biosdisk() does _not_ assume a dos formatted disk, so this is perfect for my application (it puts the burden of disk topology on the programmer, instead)... Thanks to those of you who responded! Scott L. Scott Emmons --------------- emmonsl@csus.edu <or> ...[ucbvax]!ucdavis!csusac!athena!emmonsl Packet: kc6nfp@kg6xx.#nocal.ca.usa.na
pete@wlbr.imsd.contel.com (Pete Lyall) (12/08/90)
I'm glad this thread started (reading non-DOS diskettes)....
I have been toying with trying to get my PC/AT to read OS9 diskettes.
Os9 typically uses 256 byte sectors, and also has a description
of the media in sector 0 of the disk (although I would bet it's
not in DOS edible format). Is there any mechanism (short of directly
diddling the disk controller) for reading 256 byte sectors?
To throw in a worse curve, some formats of OS9 floppy disks have a
single density track on side 0, track 0 to support prehistoric boot
EPROMS on several machines. Will PC class disk controllers even DO
single density?
Thanks for any help or hints!
Pete
--
Pete Lyall Contel Corporation
Compuserve: 76703,4230 OS9_Net: (805) 375-1401 (24hr 300/1200/2400)
Internet: pete@wlbr.imsd.contel.com UUCP: {hacgate,jplgodo,voder}!wlbr!pete trier@cwlim.INS.CWRU.Edu (Stephen C. Trier) (12/09/90)
BIOS options exist to read 256-byte sectors. When I initially got a C compiler for a PC, one of my first projects was to try to read an OS-9 disk. I was never able to get the transfer to work right. (On the other hand, I hadn't got used to PC programming yet back then!) So the answer is "yes, it's possible, at least in theory." There was a package from OwlWare a while ago that ran on MS-DOS and read and wrote Disk BASIC and OS-9 floppies. -- Stephen Trier Case Western Reserve University Work: trier@cwlim.ins.cwru.edu Information Network Services Home: sct@seldon.clv.oh.us %% Any opinions above are my own. %%
ericr@hp-vcd.HP.COM (Eric Ross) (12/11/90)
I just wrote a rough program to read a non-dos 1.2 Meg disk. It uses int 10 subfunction 2 to read from the disk. I will send sources upon request. Eric Ross ericr@vcd.hp.com
edwill@earth.lerc.nasa.gov (Glenn L. Williams) (12/13/90)
In article <1400002@hp-vcd.HP.COM>, ericr@hp-vcd.HP.COM (Eric Ross) writes... >I just wrote a rough program to read a non-dos 1.2 Meg disk. It uses >int 10 subfunction 2 to read from the disk. I will send sources upon >request. > > >Eric Ross >ericr@vcd.hp.com Does anybody have a routine to read (read only is ok) Amiga 880k 3.5" diskettes on a DOS 3.5" drive, in order to "just" get the textfiles and things off of them????
mikey@shuksan.UUCP (Mike Fields) (12/13/90)
In article <1990Dec8.182707.28401@usenet.ins.cwru.edu>, trier@cwlim.INS.CWRU.Edu (Stephen C. Trier) writes: > BIOS options exist to read 256-byte sectors. When I initially got a C > compiler for a PC, one of my first projects was to try to read an OS-9 > disk. I was never able to get the transfer to work right. (On the > other hand, I hadn't got used to PC programming yet back then!) > > So the answer is "yes, it's possible, at least in theory." > I had problems getting absread and abswrite to work - things were not where they were supposed to be. I finally figured out that absread adn abswrite refer to logical sectors which are calculated from the current drive parameters which ------ here's the gotch had to be set by first doing a dir on a disk formatted to the correct density!!! I was writing disks on my SUN at work and could not figure out why I could only get chunks of them. I finally wrote a little unix util which wrote a bunch of sectors (sequential) to disk which contained in ASCII what sector it was.. TC was getting blocks and skipping blocks. Finally figured out that the disk sort of defaults to 360K if it has not been set!. biosread() and bioswrite() allow you access to the exact sector you want but you have to fill in the head,track and sector number. I have since (read the pax doc) found that that is how other people set the density - have a blank disk formatted with dos at the correct density, do a dir on it THEN use the drive as you see fit. It works. -- Mikey (yes "he likes it!") ======================================================= Mike Fields ==> uunet!bcstec!shuksan!mikey (206) 657-6136 [work] 12022 NE 138th Pl. uw-beaver!ssc-vax!shuksan!mikey (206) 821-3492 [home] Kirkland, Wa. 98034
goldstein@arecibo.aero.org (Fogbound Child) (12/14/90)
In article <367@shuksan.UUCP>, mikey@shuksan.UUCP (Mike Fields) writes... >In article <1990Dec8.182707.28401@usenet.ins.cwru.edu>, trier@cwlim.INS.CWRU.Edu (Stephen C. Trier) writes: >> BIOS options exist to read 256-byte sectors. When I initially got a C >> compiler for a PC, one of my first projects was to try to read an OS-9 >> disk. I was never able to get the transfer to work right. (On the [massive deletion] > >I have since (read the pax doc) found that that is how other people set >the density - have a blank disk formatted with dos at the correct density, >do a dir on it THEN use the drive as you see fit. It works. > > Anybody had any success with TRS80 Mod I DSDD (360K) disks? The sectors are all numbered differently than MSDOS. Specifically, I'd like to be able to read NEWDOS 80 v2 disks. Anyone? Thanks, ___Samuel___ goldstein@aerospace.aero.org