Path: utzoo!attcan!uunet!portal!cup.portal.com!Chris_F_Chiesa
From: Chris_F_Chiesa@cup.portal.com
Newsgroups: comp.sys.atari.8bit
Subject: Re: DOS III to DOS 2.x
Message-ID: <13299@cup.portal.com>
Date: 8 Jan 89 01:55:04 GMT
References: <2625@udccvax1.acs.udel.EDU> <2626@udccvax1.acs.udel.EDU>
Organization: The Portal System (TM)
Lines: 31


(I haven't yet figured out how to get Portal to 'include' text of previous
postings... sigh...)

I once found myself needing to transfer files from DOS 3 format to DOS 2 format,
but without access to DOS 2.5 or any other "transfer utility" program.  I was
able to solve the problem by running a BASIC program that started out running 
under DOS 3, read data from the "original" file into a buffer string, then 
somehow (I have unfortunately forgotten the details but you might be able to
re-engineer it) warm-rebooted into DOS 2 without losing the data, then opened
a file (now under DOS 2) and wrote the data back out.  From the program's 
point of view, it "transparently" READ one file, and WROTE another, using
DOS-version-independent OPEN, GET, and PUT statements -- but with the altera-
tion, in the middle, of the underlying DOS support, it wound up transferring
data from one format to the other.  (It is worth noting that transfers in the
OTHER direction did NOT work when I tried them; apparently DOS 3 boots up 
differently from DOS 2, or its memory requirements are different, with the
result that the technique I used (I believe it was a USR call into the bootup
code of the OS) works ONLY in ONE direction, and not in the other.  This means
that you have to reboot anew into DOS 3 for each file you transfer.  Also, if
the file to be transferred is larger than the buffer memory size, you have to
transfer the file in several pieces (transfer the first N bytes; then reboot,
alter the program to SKIP the first N bytes of the file and transfer the NEXT
N bytes..) and then re-APPEND them under DOS 2 when you get them there.

All in all, it's probably EASIER for you to find an existing utility, but if
that pans out, this is one way to do the job with what you already have.

Chris Chiesa

   Formerly 'cfchiesa@bsu-cs.UUCP'