MODDATE.CMD
by Rick Charnes, San Francisco, 10/25/87

    The successful operation of MODDATE.CMD requires DATEREG.COM to have 
been run previously, preferably by inserting it in one's startup alias.

    This is another alias that works beautifully to do what I would like 
to teach myself to write in assembly language.

    MODDATE (to be inserted in your ALIAS.CMD) is used to manually set 
the creation date of a file.  Syntax is:

        MODDATE SMITH.LTR 05/01

where the user desires to set the creation date of SMITH.LTR to be 
May 1, 1987.

    The alias is:

MODDATE time 87/$2 12:00;time;save 0 $2;savestmp $d1$u1:$:1.$.1=$2  <<
era $2;tdir $1;time $r7/$r5/$r6 12:00;time

    First we set the system date with the TIME.COM program supplied by 
Carson Wilson in Z80DOS10.LBR.  Our second parameter is the month/day, 
which should be entered in the form 'MM/DD', with the slash included.  
The parameter becomes a parameter for TIME.COM, using '12:00' as a dummy 
time.  Running TIME again confirms that we have changed the date 
correctly.  Then we SAVE a 0-length file whose directory entry will be 
stamped with the new date.  Then SAVESTMP runs, copying the date of our 
0k file onto our current file.  Next, the 0k file, having served its 
purpose, is erased.  TDIR is run to display the changed date.  Finally, 
since we have previously run DATEREG and the system date is stored in 
ZCPR3 registers 5, 6 and 7, the next command expands as:

         TIME yy/mm/dd 12:00

which is how TIME.COM requires its parameters.  

    I'm going to try to do an assembly language version of this.  Using 
Carson's new BDOS functions should make it quite easy.