A hardware-independent "memory-disk" formatting program for CP/M+


			   Jon Saxton
			 TIE-Line RCPM+
			   AUSTRALIA
			   29 Aug 87

This program is DESIGNED to be	automatically  executed  whenever
your computer  is  "cold-booted" i.e., when  it is  powered on or
when the "reset" button is pressed.  It looks at your RAM-disk to
see whether or not it is already  formatted.   If it is formatted
then the  program does nothing	but if it  is  not  formatted (as
would probably be the case when you first switch on the computer)
then it formats the RAM-disk  and chains  to a command (which you
specify) to load whatever  files you want into	the RAM-disk e.g.

	MFORMAT NULU -o MDFILES -E P:*.* -X

If the RAM-disk is not formatted, then MFORMAT will:

	1.  Format the RAM-disk
	2.  Chain to NULU which in turn will:
	3.  Open MDFILES.LBR
	4.  Extract all the files to the P: drive
	5.  Close MDFILES.LBR

MFORMAT is hardware-independent.  It uses the BIOS disk parameter
tables to gather its  information and the BIOS disk drivers to do
the formatting.  It should run on ANY Z80 system with a RAM-drive
and CP/M Plus.	 Just include a command such as the example above
in PROFILE.SUB.

As assembled, this program assumes  drive P: is the RAM-disk.  If
yours is  different, change  the third byte of the program (102h)
to match the drive letter of your RAM-disk.  Alternatively change
the source code and reassemble.

It may be possible to port this program to CP/M 2.2.   The issues
which must be addressed are:-

1.   The BIOS calling mechanism:

     MFORMAT calls the BIOS via the CP/M 3 BDOS function 50.   It
     would  have  to be changed to access the BIOS via	the  jump
     table.

2.   Chaining to another program:

     MFORMAT uses BDOS function 47 which is not supported by CP/M
     2.2.   Since  MFORMAT is a small program,	the CP/M 2.2  CCP
     will remain intact and it may be possible to stuff something
     into  the	command buffer.   ZCPR users may find  this  task
     easier than those using "vanilla" CP/M 2.2.

3.   Disk parameters:

     Under  CP/M version 3 the physical sector size of a disk  is
     encoded  in  the disk parameter block (DPB).   MFORMAT  uses
     this  information	in  calculating the  number  of  physical
     sectors  on the disk and the number of physical  secors  per
     track.   Since disk reads and writes under CP/M 2.2 all work
     on the basis of 128-byte "logical" sectors, the calculations
     need to be modified (but only very slightly).

4.   Directory label:

     CP/M  3 supports a special directory entry type (20h) called
     a directory label.  MFORMAT looks for a particular directory
     label to determine whether or not the RAM-disk is	formatted
     and creates that label after formatting the RAM-disk.  Under
     CP/M  2.2	you'd  probably search for a particular  file  in
     (say)  user  area 15 and create an empty file of  that  name
     after formatting.

If  someone  does  port  this program to  CP/M	2.2  then  please
preserve the CP/M 3 code (use a CP/M version test to choose which
code  to  execute) and re-submit the SOURCE CODE  to  the  public
domain.

Jon Saxton,
29 Aug 87