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From: markv@uoregon.UUCP (Mark VandeWettering)
Newsgroups: comp.sys.atari.8bit
Subject: Re: DOS 2.5 vs. DOS 3.0
Message-ID: <507@uoregon.UUCP>
Date: Sun, 15-Mar-87 19:12:47 EST
Article-I.D.: uoregon.507
Posted: Sun Mar 15 19:12:47 1987
Date-Received: Mon, 16-Mar-87 06:50:50 EST
References: <8703131002.AA18512@ucbvax.Berkeley.EDU> <1555@tekigm2.TEK.COM>
Reply-To: markv@drizzle.UUCP (Mark VandeWettering)
Organization: University of Oregon, Computer Science, Eugene OR
Lines: 51

In article <1555@tekigm2.TEK.COM> wrd@tekigm2.TEK.COM (Bill Dippert) writes:
>In article <8703131002.AA18512@ucbvax.Berkeley.EDU>, Makey@LOGICON.ARPA (Jeff Makey) writes:
>. I am getting ready to buy a 1050 disk drive for my 800XL.  One the
>. mail-order ads in ANALOG Computing says that they include DOS 2.5 with
>. the drive, another says they include DOS 3.0, and the rest are silent
>. on the topic.  Some questions:

>I would strongly recommend that you use DOS 2.5.  It is the latest and greatest
>from Atari.  It is an improved version of DOS 2.0S.  DOS 3.0 is an aberration
>and is non-compatible with DOS 2.0/2.5.  DOS 3.0 is more or less abandoned by
>Atari and most users.  DOS 2.5 disks have a file on them that will translate
>DOS 3.0 file to DOS 2.5/2.0S.  

I am going to disagree with you on this one.  DOS 3 was in many ways a
superior DOS to DOS2.5 or DOS2.0.  Both 2.5 and 2.0 have the following
annoying problems:

1.	When you open a file for appending, DOS 2.5 and 2.0 both "round"
	up to the next sector before they begin writing.  In a business
	program (who uses there Atari for business, me thats who!) I
	wrote, I appended 17 byte records to the end of a transaction
	file.  The actual filesize increased by a full 128 byte sector
	however.  DOS III does the right thing, adding it directly to
	the end of the file.

2.	Note and Point are both screwy on DOS 2.0 and 2.5.  They return
	the actual PHYSICAL sector and byte number that the head is
	positoned at.  If you implement random access files by
	maintaining a table, you have two problems.  If you copy the
	file you need to remake the pointer table, and you HAVE to
	maintain a table.  Under DOS 3.0, note and point return LOGICAL
	addresses from THE BEGINNING OF THE FILE.  Now, it is relatively
	easy to find any record, and files may be copied at whim.

It is a pity that 3.0 wasn't a bigger success.  It really is a superior
DOS to 2.5.  2.5 never fixed any of the design flaws of 2.0, it only
slightly modified it to run with higher density drives.

I can't really recommend you use DOS 3.0, it is incredibly non-standard.
I like it alot however, and it offers certain things that have been
useful on several projects.  My brother uses MYDOS alot, and swears by
it.

Has anyone used DOS 4.0?  I am interested in hearing about it?  Does it
suffer from the 2.0 -- 2.5 problems?

-- 
|                       Mark VandeWettering                             |
|   member of UO-EXODOS - distributed operating system research group   |
|   University of Oregon Computer and Information Sciences Department   |
|               markv@uoregon.edu OR markv@uoregon.uucp                 |