XTCPM.DOC
                       11/22/81   RLP


REV 1.4 dated 12/4/81
Major revision that removes the need for naming transients in the 
CCP  command  table  and their addresses in  the  address  table. 
Designation   of  transients  for  password  protection  is   now 
accomplished  simply by placing them in USERs 13,  14,  or 15  on 
drive  A  for  password levels 0,  1,  or  2  respectively.   The 
directory on drive A will be universal at each password level  to 
include all transients up to the password level achieved.

                         * * * * * *

This  program  allows  you to expand your system by  one  or  two 
Kbytes  without  the  need for a  special  SYSGEN  program.   The 
additional  code is loaded directly above CP/M by the CCP  itself 
and thus does not require any movers in the code.   This is  done 
in  such  a  manner as not to clobber anything in  the  TPA  when 
loading.   The  additional code is contained in a transient  that 
you must keep on your system disk and which is formed at the same 
time  as formation of a patched CPMxx.COM file that you make with 
DDT  and XTCPM.HEX.   The DDT overlay value is calculated in  the 
PRN file and when using that value to patch in all of the patches 
in XTCPM.ASM, the code from 100H is exactly the code you need for 
the  transient  so all you have to do is SAVE 4 if it is  1KB  or 
SAVE  8 if it is 2KB.   The saved CPMxx.COM file is then sysgened 
using your normal SYSGEN program.

The  specific  implementation  here provides for  additional  CCP 
commands and pseudo CCP commands that are transients kept in USER 
13,  14  or  15  on drive A (depending  on  password  level)  and 
available  from any logged drive/user.   It also provides for two 
levels of password protection such that certain commands can only 
be executed at the 2nd level, others at the first level and a few 
at level0, i.e, before the password is entered.

This  should work with any CP/M 2.2 system wherein the CCP is  in 
the original 8080 code provided by DRC.   It has been tested with 
Lifeboat  CP/M  for  North  Star as well  as  North  Star's  CP/M 
product.   It  has also been tested with a standard  CP/M  system 
using a Micromation Doubler.  If after assembling for your system 
size,  the  location  of the BIOS in the PRN file does not  agree 
with  your  system,  simply change the ADJUST value in  the  BIOS 
equate  until it does.   Also,  make sure that the code  for  the 
USER2 code area appears at 100H after doing the DDT overlay.
.