Assem Posted February 13, 2009 Share Posted February 13, 2009 Hello, Does anyone know where I can find a disk image of the dreaded DOS 3? I have had a look in a few places including Atarimania but have had no luck. Cheers Assem Quote Link to comment Share on other sites More sharing options...
drac030 Posted February 13, 2009 Share Posted February 13, 2009 http://atariki.krap.pl/index.php/DOS_3.0 Quote Link to comment Share on other sites More sharing options...
Assem Posted February 13, 2009 Author Share Posted February 13, 2009 That was quick! Thanks Drac030. Quote Link to comment Share on other sites More sharing options...
Bryan Posted February 13, 2009 Share Posted February 13, 2009 Are you planning to use it, or just make a copy so you can burn it? Quote Link to comment Share on other sites More sharing options...
LYNXGUY Posted February 13, 2009 Share Posted February 13, 2009 I thought i saw a pic of DOS 3 on this site along with many other DOS pics ?? Quote Link to comment Share on other sites More sharing options...
carmel_andrews Posted February 13, 2009 Share Posted February 13, 2009 was dos 3 the one with possibly the worst bug on any atari dos Quote Link to comment Share on other sites More sharing options...
Fletch Posted February 13, 2009 Share Posted February 13, 2009 If by bug you mean incompatible with DOS 2 then yes was dos 3 the one with possibly the worst bug on any atari dos Quote Link to comment Share on other sites More sharing options...
Bryan Posted February 13, 2009 Share Posted February 13, 2009 was dos 3 the one with possibly the worst bug on any atari dos DOS 3 was an ambitious project to create an extensible DOS that could handle larger storage devices. It was incompatible and frustrating for the average user who was only using floppy drives. Maybe it would have been useful if the 1090 had resulted in new storage options. In the end it was just another hole into which Atari poured money. Once it was clear that DOS 3 was a flop, Atari released DOS 2.5 to support the 1050's dual density. Quote Link to comment Share on other sites More sharing options...
carmel_andrews Posted February 13, 2009 Share Posted February 13, 2009 If by bug you mean incompatible with DOS 2 then yes was dos 3 the one with possibly the worst bug on any atari dos Sorry i should have mentioned, i was referring to the bug where it only writes so much data per sector, and if you write a sector that has one byte over the max amount of data in that sector, it get's put onto the next sector and that sector cannot be written to Quote Link to comment Share on other sites More sharing options...
Bryan Posted February 13, 2009 Share Posted February 13, 2009 I haven't heard that one. What I do know is that DOS 3.0 used the cluster concept like MS-DOS and thus required disk usage to be in increments of 1K instead of a single sector. A file with 1025 bytes consumed 2K. Quote Link to comment Share on other sites More sharing options...
Urchlay Posted February 13, 2009 Share Posted February 13, 2009 Sorry i should have mentioned, i was referring to the bug where it only writes so much data per sector, and if you write a sector that has one byte over the max amount of data in that sector, it get's put onto the next sector and that sector cannot be written to That description applies to pretty much any DOS. Where it gets nasty for DOS 3 is that the "sectors" are actually 8-sector (1Kbyte) chunks of the disk. So if you write a file that's one byte larger than the 8-sector chunk, it has to use 2 of them, or 16 sectors... which is a huge waste (8 sectors is over 1% of a single density disk). DOS 2/2.5 would use 9 sectors in that case. ...though, DOS 2/2.5 only use 125 data byte per 128-byte sector, and IIRC DOS 3 has less overhead per sector (maybe it uses 1021 data bytes per 1024-byte chunk? It's been many moons since I last used DOS 3) I do remember back when I first switched to DOS 2.5, I wrote a (probably) Turbo BASIC program that would read a DOS 2.5 disk's directory and calculate how much storage would be wasted if the same files were copied to a DOS 3 disk instead. Probably still have the floppy that's on, wonder if it's still readable... Quote Link to comment Share on other sites More sharing options...
drac030 Posted February 13, 2009 Share Posted February 13, 2009 DOS 3 has less overhead per sector (maybe it uses 1021 data bytes per 1024-byte chunk? No, as it has been already written above, DOS 3 has FAT. One 128-byte sector is sacrificed for that, and it contains information necessary to map the entire disk (127 clusters, 1k each). The data clusters are filled with data completely, no links there. Quote Link to comment Share on other sites More sharing options...
Tickled_Pink Posted February 13, 2009 Share Posted February 13, 2009 I had DOS 3 shipped with my original 1050. I quite liked it but then was urged to move to DOS 2.5, which didn't seem any better until I discovered the wastage issues. I'm sure I still have my original DOS 3 disk - but it's long ago had DOS 2.5 shoved onto it. Quote Link to comment Share on other sites More sharing options...
Urchlay Posted February 13, 2009 Share Posted February 13, 2009 No, as it has been already written above, DOS 3 has FAT. One 128-byte sector is sacrificed for that, and it contains information necessary to map the entire disk (127 clusters, 1k each). The data clusters are filled with data completely, no links there. Written above, where? The external link? It's in Polish, I apologize for not being able to read it... Quote Link to comment Share on other sites More sharing options...
drac030 Posted February 13, 2009 Share Posted February 13, 2009 Written above, where? The external link? No, "above" does not mean "in the external link". I meant the "cluster concept like in MSDOS" mentioned in post #10. The mentioned MSDOS similarity is not in "clusters" alone, but how they're mapped to files: this is what can be called FAT 8. I admit that this may have been cryptic for you, so apologies for being unclear. Obviously, FAT 8 (one byte per FAT entry) means that the maximum number of clusters possible to map this way is 256. So this filesystem is limited by design to 256k, and in fact to 128k (because the FAT takes only 1 sector). So in fact it is rather minimalistic DOS, probably designed to be used with two 1050 disk drives and nothing bigger (this is my comment to post #8 ). Quote Link to comment Share on other sites More sharing options...
+bf2k+ Posted February 13, 2009 Share Posted February 13, 2009 (edited) Sorry i should have mentioned, i was referring to the bug where it only writes so much data per sector, and if you write a sector that has one byte over the max amount of data in that sector, it get's put onto the next sector and that sector cannot be written to That's not a bug... it used 1k clusters. Oops I should have read on before 'replying'... sorry. Edited February 13, 2009 by bf2k+ Quote Link to comment Share on other sites More sharing options...
+bf2k+ Posted February 13, 2009 Share Posted February 13, 2009 I had DOS 3 shipped with my original 1050. I quite liked it but then was urged to move to DOS 2.5, which didn't seem any better until I discovered the wastage issues. I'm sure I still have my original DOS 3 disk - but it's long ago had DOS 2.5 shoved onto it. My 2 original 1050's had DOS 3 - both disks were bad. A friend finally hooked me up with DOS 2.. the drives were fine. Quote Link to comment Share on other sites More sharing options...
Urchlay Posted February 13, 2009 Share Posted February 13, 2009 No, "above" does not mean "in the external link". I meant the "cluster concept like in MSDOS" mentioned in post #10. The mentioned MSDOS similarity is not in "clusters" alone, but how they're mapped to files: this is what can be called FAT 8. I admit that this may have been cryptic for you, so apologies for being unclear. Makes more sense now, thanks. Been a long time since I messed with either DOS 3 or MS-DOS... Obviously, FAT 8 (one byte per FAT entry) means that the maximum number of clusters possible to map this way is 256. So this filesystem is limited by design to 256k, and in fact to 128k (because the FAT takes only 1 sector). So in fact it is rather minimalistic DOS, probably designed to be used with two 1050 disk drives and nothing bigger (this is my comment to post #8 ). It's kind of a weird design in that sense... using 1K cluster size seems more like something you'd do on larger volumes where the wasted space has less impact, but the 8-bit FAT indexing means you're stuck with tiny volumes... so I wonder how they came up with it. It's like having the worst of both worlds. Possibly the original designer was designing for hard disks, or 720K floppies, then later on was told "no, this is for the 1050 only, the 1090 isn't being produced" and made the best compromise he could without scrapping the whole thing. Quote Link to comment Share on other sites More sharing options...
carmel_andrews Posted February 13, 2009 Share Posted February 13, 2009 Perhaps we should have a 'buring dos 3' ceremony ....if there are enough copies out there Quote Link to comment Share on other sites More sharing options...
spookt Posted February 13, 2009 Share Posted February 13, 2009 I have at least 6 original DOS 3 disks. No idea if they work, I've never tried to read them. Quote Link to comment Share on other sites More sharing options...
Rybags Posted February 14, 2009 Share Posted February 14, 2009 I don't recall DOS 3 having any bugs... in any case, it wasn't in general use long enough for people to work out if anything didn't work as it should. IMO, DOS 3 is in the same bucket as Basic A and B - should be kept offline to prevent people possibly using it and having the bad experience associated with each product. Quote Link to comment Share on other sites More sharing options...
+CharlieChaplin Posted February 14, 2009 Share Posted February 14, 2009 Well, wasn`t the author of DOS 3 the same one who created DOS XE ?!? Afaik, DOS XE uses 256-byte clusters, so with DOS XE SD disks have approx. 350-360 free sectors, ED disks have 505-520 free sectors and only DD-disks have approx. 707 free sectors... and DOS XE was awkward to use also... On the other hand, there were some commercial german and austrian programs relying on DOS 3, think it was A-Text or Austro-Text (not sure which one, I always mix them) and also A-Base or Austro-Base... the type-in listing of "Expedition" (a cavern/shooter game a la Caverns of Eriban, etc.) by Oliver Cyranka was also based on DOS 3 and did not work with DOS 2.0 or DOS 2.5 - until Homesoft patched it to do so... (you can find the corrected version on one of the Homesoft disks)... -Andreas Koch. Quote Link to comment Share on other sites More sharing options...
drac030 Posted February 14, 2009 Share Posted February 14, 2009 (edited) I don't recall DOS 3 having any bugs Its menu has at least one: the "File index" function hangs, when the left margin is set to 1. DOS 3 is in the same bucket as Basic A and B - should be kept offline to prevent people possibly using it and having the bad experience associated with each product. Well, there is a difference. BASIC A and B have serious bugs, that's why they shouldn't be used. DOS 3.0 isn't bad by itself. I don't find DOS 2.5 any better (and it lacks the help system) The same for DOS 4.0 (now this is a monster, it uses six sectors per cluster in DD). Both probably were attempts to get rid of that silly file system introduced with DOS 1.0 and continued in 2.0 and 2.5 (and all clones, like MyDOS). Edited February 14, 2009 by drac030 Quote Link to comment Share on other sites More sharing options...
Rybags Posted February 14, 2009 Share Posted February 14, 2009 FAT is a better way, for sure. Problem is, you either need to keep the FAT in RAM, which would equate to almost 700 bytes for FAT12 on ED 1040 sector disks, or keep having to seek/read to it when writing a file. The way they did it with DOS1/2, it's only necessary to keep the relevant VTOC sector in RAM, and the file links just get written to the data sectors. Quote Link to comment Share on other sites More sharing options...
drac030 Posted February 14, 2009 Share Posted February 14, 2009 FAT is a better way, for sure. Problem is, you either need to keep the FAT in RAM, which would equate to almost 700 bytes for FAT12 on ED 1040 sector disks, or keep having to seek/read to it when writing a file. You can always make sector clusters, like in DOS 3.0 and 4.0, and this keeps the FAT 8-bit and makes it fit in 1 sector. This has the disadvantage of wasting space, especially for small files, but at the other hand expanding FAT entries makes the FAT bigger and the filesystem becomes sensitive to fragmentation. You don't have to keep FAT (nor VTOC) all the time in memory, which for bigger FAT (and VTOC, like in MyDOS, up to 8 KB) sizes isn't even possible, but the more fragments you have, the more FAT sectors you have to access to read the data of the fragmented file. This is why MSDOS/Windows users pay so much attention to defragmentation The way they did it with DOS1/2, it's only necessary to keep the relevant VTOC sector in RAM, and the file links just get written to the data sectors. Yes. But the price is that it is very difficult to build an effective database for that FS, because you have to do indexing of data files, wasting time and disk space. Note that FAT, even it has own disadvantages by itself, does not have this difficulty (of course, much depends on implementation). Considering that Atari aimed at the "real computer" market in 1978, I can't believe they released such an amateurish filesystem. Quote Link to comment Share on other sites More sharing options...
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