BACKUP.ASM	 USED TO BACKUP HARD DISKS
	WRITTEN BY G. YOUNG, PO BOX 3218, NO. HOLLYWOOD, CA 91609
 
    The Winchester hard disk offers file storage approaching mainframe
performance on microcomputers.	The problem of backing up the data is
a serious drawback, however.  The only option currently available is to
use PIP to copy one file at a time.  To PIP an entire file type would
quickly fill a floppy and not copy the rest of the files.  To PIP one
file at a time would be unbearably time consuming.  Another alternative
is obviously necessary. 
     BACKUP is used to copy files from large volume hard disks to low
volume floppy disks for backup and recovery purposes.  It is intended
for CP/M files where the entire file will fit on one floppy disk. 

     Updated to v2.1 by Ron Stevenson
     This update corrected some problems that I found in the code as well
as added Prompted messages at the begining to ask for the drives of the
hard disk to backup then ask for the floppy disk to backup to.	This data
is check for correctness before the date is ask for.

     Updated to v2.2 by Ron Stevenson
     Put some neat stuff in for setting attributes for Molecular computers
which is the 't3' byte or at asm time can be configured for other computers
to set the 'f4' byte.  I found with my computer (EXO Nobus running CP/M 2.2
with ZCPR1) that most of the programs I use will erase the 'f4' byte when
the file is updated and the FCB block is written back but some will not.
What happens is if the file is updated, the byte sould be reset or cleared
of that attribute.

     There are three phases in BACKUP.	The first phase reads the
directories of all the hard disks, sorts the file names into alphabetical
order within file type, and prints a master directory by type on the list
device.
     Next the program attempts to restrict the files it backs up.  Since
a twentysix megabyte disk could take up to forty four double density
floppy disks to completely back up, only essential files are saved.
Duplicate files are eliminated saving only the file on the lowest
drive (A: is saved if the file also exists on B: or C:).  The file
is considered duplicate if the names are the same, the actual contents
are not compared.  Certain file types are considered unnecessary and
are not saved.	PRN, BAK, SYM, HEX, and TMP  are eliminated from the
backup list.  To change this list of skipped file types, simply change
the variable NOSKIP and SKIPFILES within the program and reassemble.
Each file type will then be displayed on the console and the program will
ask if you want to back up all of the files of this type (enter Y), skip
all of the files of this type (enter N), or select certain files within
this type (enter S).  If you enter S, each file name within the current
type will be displayed on the console and the program will ask if you
want to backup this particular file (enter Y), skip this file (enter N),
or continue to backup all the rest of the files within this type without
listing each name (enter C).  This feature is used to restart the backup
if it was terminated before it completed during a previous run.  At
this time you can also skip any files that will not fit entirely on  
one disk.  The program will skip this file also if it encounters it, but
it will prompt for a blank diskette to try the backup before it discovers
that it cannot be backed up with this program.	When the list of files
to backup has been reduced, the list will be printed and the program will
ask if it should begin the copy procedure or abort.  This allows you to
rerun if the list of files to backup is not correct. 
     Finally, the backup procedure will begin.	The program uses all of
RAM from the end of the file list table to the end of the TPA as the
buffer for copying files.  As the files are finished being copied, the
tabled is decreased and the buffer area is increased thereby speeding up
the copy process.  The program will display a message asking to mount
a floppy in the first drive (assumed to be D: but changable with the
program) and enter a three digit disk id or "END" to terminate
prematurely.  This may happen if you run out of diskettes!!!
The first file that BACKUP writes on the floppy is a null file.  It
has zero length so it only takes up one directory entry and no space on
the disk.  This null file has the name equal to the eight character date
listed on the reports and the file type is the three character disk id.
The purpose of this file is to identify the disk against the directory
listing and to automatically mark the date.  The
heading line for an index report will then be printed on the list
device showing the disk id and current date.  As the files are copied,
the index report is created showing the files copied to each floppy.
While the file is being copied, the file name will be displayed on the
console.  When the file has been completely copied, the file name will
be added to the index report.  If the file will not fit completely on
the floppy, the file name will be deleted from the floppy directory, a
new floppy requested, and the file recopied to the new floppy.	This
process continues until the entire file name table has been processed
using as many floppy disks as required. 
     Restoring or recovering can be done with PIP or SWEEP.  You can PIP
or SWEEP the entire floppy disk to the hard disk, or using the disk id/file name index, restore only certain files. When using PIP to copy any REL files back to the hard disk, be sure to use the OV option in PIP. 
     The source code is provided in file BACKUP.ASM for your convenience
in changing certain parameters for your installation.  The variables that
may need to be changed are all on the first page of the source and are
the following:	
NOSKIP	   This is the number of file types in the file skip list.
SKIPTYPE   This is the list of file types to skip.  It is normally set
	   to PRNHEXSYMBAK$$$TMP to skip those six file types.
LINESPAGE  This is the number of lines per page and is used to print the
	   various directories.
RECLINE    This is the number of file names that will appear on one line
	   in the directories.

    The program uses the COMPUTIME board to get the date, but the code
is in the program to request the date from the console.  Just remove
the * in the columns to convert the code from comments if you do not have
a clock board.