FOUR DRIVES FOR THE P-SYSTEM 
 
   These programs are adapted from source code provided by Anders Persson to
run on either the Corcomp or Myarc floppy disk controllers.  Used as
directed, they will install a fourth floppy drive as Unit #10 on system
startup and any time the system is Initialized.  The program SYSTEM.STARTUP
checks the format of the boot disk and calls the program AUTOST.CODE.  With
the Myarc controller, SYSTEM.STARTUP must be on first track of the boot disk
-- it replaces the program of the same name on the UBOOT disk.  AUTOST.CODE
does a series of steps to initialize the system (prompts for and sets system
date, sets the system pointers for I/O unit #10, sets the com ports and the
default volume).  This program in turn calls CHECK.CODE which polls the
drives and determines and reports the disk format of each volume.  This last
step is necessary to use the full capabilities of the Myarc controller. 
    
   The programs are available in two forms.  The first, PSW4, is a
compressed, DCOPYed image of a P-system disk containing the three programs
with source code.  If you are using UBOOT, replace SYSTEM.STARTUP and add
the other two executable files from PSW4 to your boot disk.  BOOTGN440 is an
upgraded boot disk, coded using DCOPY and compressed with ARCIIv2.4.  It
contains several other files from the Swedish Pascal disk, including the
enlarged SYSTEM.LIBRARY (includes COMMANDIO and SCREENOPS units) and
SYSTEM.PASCAL as well as a DFORMAT utility that works for double-sided disks
on any controller and 80 track disks (using the Charlton quad eprom on the
Myarc controller).  NOTE that the location of SYSTEM.PASCAL depends on its
size and cannot be changed if the disk is to function with all Myarc
eproms. 

   The procedure to recover the files is the same in either case.  The
downloaded file should be decompressed and unpacked with ARCIIv2.4 (or
v2.3).  The result is a DCOPY image which can be recovered, using that
utility, as a P-system format disk (360 sectors for PSW4 and 1440 sectors
for BOOTGN440).  The PSW4 files can then be added to your boot disk.  For
BOOTGN440, your other system files can be added to the recovered disk if you
are using 40 track drives or copied in order to a Zeroed 80 track disk (no
duplicate directory) to create a new quad (2880 sector) boot disk. 

                                             Jerry Coffey -- June 1988