rfrost@cs.ua.oz.au (Richard Frost) (02/18/90)
I would like to know if anyone has developed an alternative DOS for the
Amiga? I recall a rumour that the Software Distillery had created one. I would
like to know about this as I have had my Amiga for over 3 years now and I had
just about enough of it! We all know of FFS but it was not the improvement I
was looking for! For example, I copied over 200 files from the RAM disk to
a FRESHLY FORMATTED floppy disk and it took over 4 minutes! Each file averaged
about 1-2 K. Also, the file names were very similar, thus increasing the
possibility of hash-collisions in the DOS!! The disk fragmentation was
appalling, a directory alone took 2 minutes! What sort of brain damaged DOS
is this??? Yes, it may be fast for all those hard disk users out there, but
they are a minority! The floppy disk is the storage medium, that most people
(ie. like me) are FORCED to use (I admit I have extra memory to remedy this).
What I would want for the Amiga is a DOS that is FAST, ie. (Excuse
me for saying this..) the IBM disk format which uses a File Allocation
Table, which gives FAST directory listings! Although the FAT idea is not so
good with hard disks which need VERY large FAT's, the use of them in floppy
disks is quite ok. Alternatively Commodore should model a DOS like that
used in UNIX which uses I-nodes.
One final question, why didn't they put the FILENAME strings in the
directory block for the Amiga and not the hash table, which requires yet
more disk head seeks to seek the filename string!!!
Gee, I feel a lot better now, after getting all that out of my
system !!!
--
______________________________________________________________________________
_ ___ | Email Address: rfrost@spam.ua.oz.au
I) I_ |
I\ ichard I rost | FidoNet (ADAM LINK BBS): 680/805 Richard Frost
---------------------+--------------------------------------------------------
THE AMIGA,the programmers dream machine!!
Bewildered Earth Scientist: "How do you re-wire alien equipmnent like that??"
Dr. Who: "Its easy when you've had 900 years experience in alien technology."
______________________________________________________________________________stroyan@hpfcso.HP.COM (Mike Stroyan) (02/19/90)
> I would like to know if anyone has developed an alternative DOS for the > Amiga? I recall a rumour that the Software Distillery had created one. I would > like to know about this as I have had my Amiga for over 3 years now and I had > just about enough of it! We all know of FFS but it was not the improvement I > was looking for! For example, I copied over 200 files from the RAM disk to > a FRESHLY FORMATTED floppy disk and it took over 4 minutes! Each file averaged > about 1-2 K. Also, the file names were very similar, thus increasing the > possibility of hash-collisions in the DOS!! The disk fragmentation was > appalling, a directory alone took 2 minutes! What sort of brain damaged DOS > is this??? Yes, it may be fast for all those hard disk users out there, but > they are a minority! The floppy disk is the storage medium, that most people > (ie. like me) are FORCED to use (I admit I have extra memory to remedy this). > > rfrost@cs.ua.oz.au (Richard Frost) / 8:57 am Feb 18, 1990 / You should try FACC II from ASDG. This floppy accelerator program caches disk blocks, reducing the number of head seeks required. It can be configured to favor the blocks that hold directory structures. Running FACC II is about the equivalent of having a new DOS. Mike Stroyan, stroyan@hpfcla.hp.com
ckp@grebyn.com (Checkpoint Technologies) (02/20/90)
In article <RFROST.90Feb19022710@spam.ua.oz.au> rfrost@cs.ua.oz.au (Richard Frost) writes: >I would like to know if anyone has developed an alternative DOS for the >Amiga? I recall a rumour that the Software Distillery had created one. I would >like to know about this as I have had my Amiga for over 3 years now and I had >just about enough of it! We all know of FFS but it was not the improvement I >was looking for! I know what you mean. What you really want is a new file system, not a new DOS. (A new DOS will be available shortly, it's called Unix; and there are still rumors of Minix and OS9 though I believe those will not come to fruition.) Were you to receive a new DOS youd complain that all your programs no longer worked. With a new filesystem you'll preserve your software investment. And now, having said that - as far as I know, there are no alternative file systems besides FFS and Cross-DOS (which gives you a 720K MS-DOS-format floppy drive).
aduncan@rhea.trl.oz.au (Allan Duncan) (02/20/90)
> about 1-2 K. Also, the file names were very similar, thus increasing the > possibility of hash-collisions in the DOS!! The disk fragmentation was NO, NO! If the hash routine works, then changing a file name by just one bit in one character should give a completely different hash value. If it doesn't, then it isn't being hashed! Allan Duncan ACSnet aduncan@rhea.trl.oz ARPA aduncan%rhea.trl.oz.au@uunet.uu.net UUCP {uunet,hplabs,ukc}!munnari!rhea.trl.oz.au!aduncan Telecom Research Labs, PO Box 249, Clayton, Victoria, 3168, Australia.
poirier@dg-rtp.dg.com (Charles Poirier) (02/23/90)
In article <1059@trlluna.trl.oz> aduncan@rhea.trl.oz.au (Allan Duncan) writes: >> about 1-2 K. Also, the file names were very similar, thus increasing the >> possibility of hash-collisions in the DOS!! The disk fragmentation was > >NO, NO! If the hash routine works, then changing a file name by just >one bit in one character should give a completely different hash value. >If it doesn't, then it isn't being hashed! They may be different, but not necessarily "completely" different. For some hash functions and collision-handling methods, things can get bad. I can't speak to AmigaDOS' hash algorithm, but there are many simple hash functions where names differing by just the final letter give hash values differing by just the difference of those letters. This can generate a clump of consecutive entries, which can make hash collisions more severe. Particularly so if the collision algorithm is "step ahead to the next unused entry". Again, I don't know if Amy's hashing does this, just speaking in general. Cheers, Charles Poirier
dill@sybil.cs.Buffalo.EDU (Peter Dill) (02/23/90)
In article <350@xyzzy.UUCP> poirier@dg-rtp.dg.com ( Poirier local) writes: > >They may be different, but not necessarily "completely" different. >For some hash functions and collision-handling methods, things can get >bad. I can't speak to AmigaDOS' hash algorithm, but there are many simple >hash functions where names differing by just the final letter give >hash values differing by just the difference of those letters. This can >generate a clump of consecutive entries, which can make hash collisions >more severe. Particularly so if the collision algorithm is "step ahead >to the next unused entry". Again, I don't know if Amy's hashing does this, >just speaking in general. Here is the hash function from FF20: main( argc, argv ) int argc; char **argv; { if( argc != 2 ) { printf( "Usage: %s <name>\n", argv[0] ); exit( 1 ); } printf( "hash is %ld\n", (hash( argv[1] ) % 72) + 6 ); } hash( s ) unsigned char *s; { int i; int res; unsigned char *sp; unsigned c; res = strlen( s ); for( i = 1, sp = s; *sp; i++, sp++ ) { c = *sp; if( c >= 'a' && c <= 'z' ) { c = c - 'a' + 'A'; } res = ((res * 13 + c ) & 0x7ff); } return( res ); } It looks to me like keys that differ in just in the final character could generate hash values that differ only by the difference of the last value. Perhapse (res +c)*13 would be a idea to prevent this but I don't think it matters in the case of Amiga Dos anyway my quick look at the Dos manual made it look like hash values are chained together. So contrary to the assert- ion of the orginal poster similar file names (differing in the last character ) would make collisions *less* likely. So "dataX" and "dataY" are very likely to hash to different values unless X and Y are the same letter in different cases. Back to the the original post- was he *sure* he was using FFS on the floppy? BTW, no I don't know what 'i' is doing in that loop either :-). Maybe sp had an index at one time. Peter Dill dill@cs.buffalo.edu "I've got more data on wrestling than Voyager has on Neptune" -RRP
perley@trub.crd.ge.com (Donald P Perley) (02/23/90)
In article <RFROST.90Feb19022710@spam.ua.oz.au> rfrost@cs.ua.oz.au (Richard Frost) writes: >I would like to know if anyone has developed an alternative DOS for the >Amiga? > What I would want for the Amiga is a DOS that is FAST, ie. (Excuse >me for saying this..) the IBM disk format which uses a File Allocation >Table, which gives FAST directory listings! Although the FAT idea is not so >good with hard disks which need VERY large FAT's, the use of them in floppy >disks is quite ok. If you want the IBM format, why not use CrossDos? You have to live with whatever the file name restrictions are, but you get fast directory listings (I don't know, just taking your word on that). Someone suggested using FACCII caching software. The problem with that is that: 1) you have to read the data the first time. 2) it flushes the buffers if you remove the disk and put it back later. I still like FACCII better than addbuffers, it is just not the ideal solution for your complaint. -don perley perley@trub.crd.ge.com