;
                                 CLRRSX.COM                                   

             Size (recs) CRC   Version    Author/Latest Issue      Disk
               1k (6)    20DB  1.1        Jay Sage 7/86            Z3COM8

  1- Usage  2- Notes                                                          

   CLRRSX is  used  to  remove  any installed  RSX (resident system extension)
modules that are present.  An  RSX is  deemed to  be present  if  the warmboot 
vector at 0001h does  not point to an address ending in 03, or the BDOS vector 
at 0006h does not point to an address ending in 06, or the BIOS and BDOS pages
do not differ by 0EH.  
:1

   Usage:  CLRRSX<cr>

   CLRRSX installs itself  automatically  the first time it is run with no RSX 
present by copying the virgin BIOS jump vectors  into  a buffer  at the end of 
the program.  (As of version 1.1,  the program also saves  the original BDOS+6 
entry point and  the jump address  to  which it  branches.  This  is what some 
above-the-BIOS  system extensions use to  divert BDOS  calls since they do not 
have to protect the CCP.) 

   Subsequently, if  it is  called  with  an RSX present, it restores the BIOS 
jump table (Version 1.1 restores jump address at BDOS+7) and warm boots.

   When it  is called with  an RSX present and it has not been installed, then 
an error message is given.  Similarly,  an error message  is given when it has
been installed already but is called when no RSX is present.
:2

CLRRSX Notes:

   a. Note that the  file name in the FCB at the beginning of the code must be 
      the actual name  of the program  in order to carry out the installation.
      Once the program has been installed, however, it can be renamed.

   b. Version  1.1  adds  two  additional  capabilities:  it  now  checks  for
      alteration of the  jump table  as an  RSX  condition, except  when being 
      installed, in  which case  it would have no reference to check from.  It 
      also restores  the original initial  BDOS jump address at BDOS+7.  These 
      two additions  make CLRRSX useful for detaching BDOS/BIOS-diverting code 
      that does  not  alter  page 0,  such  as  Plu*Perfect  DateStamper  when 
      relocated above the BIOS.  This makes  it possible, for example, to load
      DateStamper into the IOP buffer at IOP plus  an offset for the dummy IOP 
      code, detach it at will with CLRRSX,  and reload it afterwards (INIT.IOP 
      would have to  be LDRed into  place  before reloading  DateStamper if an 
      active IOP is in the buffer - or patch the DS loader to patch in a dummy
      IOP segment before loading the actual DS code).
   CD  may 
require a password to move to the new directory.  

   In the ZCPR3 environment, 