home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
The C Users' Group Library 1994 August
/
wc-cdrom-cusersgrouplibrary-1994-08.iso
/
vol_100
/
193_01
/
backup.txt
< prev
next >
Wrap
Text File
|
1985-11-14
|
5KB
|
104 lines
BACKUP
------
The concept behind "backup" is to use byte "t3" of the
file name which, for those unfamiliar with the CP/M
organisation is the third character in the "type"
extension to the name. For example, the name -
backup.c
consists of -
name ==> "backup"
and type ==> "c" which, as you have already
noticed doesn't contain 3 characters. But not to worry,
CP/M makes PROVISION for three characters which, if not
actually used, are converted to spaces (ASCII 32, decimal).
So, whether or not you choose to specify 3 characters in the
extension, you always have 3 available to you and so we can
set bit 7 in t3 (or un-set it) as we need to in the backup
programme. In fact this is what the programme does after
it has archived (copied to the archive disk) the file(s)
which haven't been previously archived by BACKUP.
i.e. it then sets bit 7 of t3 to let BACKUP know that you
have already archived this file.
When you alter the file again, most text editors un-set the
attribute bits in t1, t2 and t3 so that BACKUP will then
regard the altered file as one which was not previously
archived (which is true) and will archive it for you in the
normal course of events.
If YOUR text editor doesn't do this then use the companion
programme SETATR ( set attributes) to make the edited file
copyable, and BACKUP can then archive it for you.
A couple of special point to be aware of when using BACKUP
are -
A. It can be used to back-up a hard disk but, the first
time you use it you should have previously used
SETATR to make sure your normal "COM" files are not
needlessly backed-up to the floppy disk. You may
also wish to disqualify all those other files which
you already have 3 copies of, on floppy disk, and
only archive the more recent work which you never
seem to have the time to archive, usually.
B. Don't worry if you find you have filled the archive
disk before archiving all the files on the master
disk. Just put another (clean, formatted) disk in
the target drive, do a CONTROL-C, and re-run BACKUP.
It won't re-copy the files it copied to the first disk
but will start again from the file it wouldn't copy to
the disk which became full, and copy the rest of the
files to the new disk.
C. The normal usage of BACKUP is -
backup d1 d2 <RETURN>
where "d1" is the drive being copied and "d2" is the
drive which contains the archive disk. Either lower
case or upper case is OK but note particularly that
"d1:" is wrong. Just enter the letter without the
colon as BACKUP only expects a single character.
If you don't remember this, or the order in which the
transfer is made -
FROM d1 TO d2
then just enter backup <RETURN> and respond to the
prompts which appear on the screen.
D. I didn't put in any special error handling functions
to deal with the problem you will encounter when you
try to back up a file which has been made R/O on the
archive disk. It was easy enough to remove the R/O
status with the "set_bit" routine, and then erase the
file on the archive disk before making the new copy
with BACKUP.
So beware, BACKUP will copy your files NO MATTER WHAT!
That's about all there is to it. BACKUP is a simple
programme (which does a complex job) and I've kept it that
way as I've seen a number of similar programmes in Public
Domain software, but NONE of them worked when I tried them
on my system! Backup SHOULD work on any CP/M 2.2 system
but if you have any problems send your bug reports to -
Phil Cogar,
P.O. Box 364,
Narrabeen,
N.S.W. AUSTRALIA 2101
-------------------------
isk