
                            -----------------------
                            Manual for N_SYSCOM 1.1
                            -----------------------

    It  is  now possible to  see  the  Gemdos,   Bios,  Xbios and GEM  (AES
    and  VDI) actions your computer  is  doing on screen.  N_SYSCOM.ACC can
    only be run as  an  accessory;   settings   can   be changed (not saved
    however) by clicking  on  the "System   Command"  menu.  You can choose
    between showing or  not   showing   the  system  commands.  Clicking on
    "Yes"  leads  to  the  question  about   the   position  you  want  the
    information showed.  "Top" means at the top of the screen, "Menu" means
    just under the  menu  bar  and  "Bottom"  means  at  the  bottom of the
    screen.

    The momentary value will be  the  default  button.  Defaults at startup
    are  "No" and "Bottom".

    Information   will  be  displayed  with  the  system  8x8  font;   this
    information  is written to the  screen  directly,   which is the reason
    N_SYSCOM only works  with the highest,  monochrome resolution.  Writing
    to the  screen  is  done  with  a  VBL  routine,   which   writes   the
    information each time the screen  has   renewed  4 times, so about 72/4
    times per second.

    The VBL routine is installed in the  first  entry in the VBL queue with
    the XBRA  id  "NSC1".  The  vector  already   installed  there  will be
    executed after this VBL routine is ready.

    N_SYSCOM installs its own Gemdos,   Bios,   Xbios and Gem vector.  This
    is  done with the same  XBRA  id  "NSC1".   The  op-code sent to one of
    those system vectors is  translated  in  a  'normal'  readable code and
    printed on screen. The  opcode  is  then  sent  to  the original system
    vector, so no commands are lost ...

    Showing  the information on the screen takes time.  Some measures  with
    Quick Index  1.6  show  that  your  Atari  is working at about  95%  of
    the   original  velocity  when   N_SYSCOM   is   installed;   there  is
    practically  no  loss  when  no information  is shown ...

    N_SYSCOM works with all TOS  versions  and in High resolution (640*400)
    only ...

    There  are no bugs known about  this program except the ones  described
    above, which are not  bugs  actually.  This  program is strictly Public
    Domain, so it may not   be   sold   in   any way.  N_SYSCOM.TXT  should
    always  be  accompanied  by N_SYSCOM.ACC and the other way around.  Use
    it at your own risk (though,  what can happen?).

    N_SYSCOM is written in assembler. The  actual  code is only 1000 bytes:
    the rest is  data  (all  the  'readable'  commands  have  to  come from
    somewhere!). The source can be obtained for  a small fee.  Write to the
    author for further information.

                              -------------------
                              Update N_SYSCOM 1.2
                              -------------------

    N_SYSCOM  1.1  has  a bug,   which  did  not get my  attention  because
    it  never happened to me...  The  line with the information is skipping
    1 pixel  sometimes and  sometimes  the  whole  infoline  is filled with
    garbage.  This happened because  I   added   d0.b   as  d0.w to a0 (for
    those of you who know  what   I   am   talking about).  That was all. I
    always use N_SYSTEM.ACC which has its  own  VBL routine, and  this  one
    clears d0.l,  so adding  d0.b  as  d0.w  does  not  lead   to  any  bug
    behaviour.

    At the request  of  several  people  I  added  the  option  to save the
    settings.  This is done  by  writing  to  N_SYSCOM.ACC  at the bootdisk
    directly.  If  N_SYSCOM.ACC does not exist  or does not have the proper
    filelength an alertbox will tell you so.

    I also added the possibility to slow  down your computer in order to be
    able  to follow what's going on  in  a  more detailed way. The alertbox
    with the "Slow  down  computer"  question  has  the  options  of "Much"
    (almost all computer action can be  followed,  but serious computing is
    out of the question), "Little" (make an  IBM  PC of your Atari) or "No"
    slowing down.  VDI actions are still  hard  to  follow even when "Much"
    is selected.  "Much" slows your computer  down to 6%,  "Little" to 50%.
    Those values can vary when you're  using other VBL installing programs.
    All the slowing down routine  does is   consume CPU time. When too much
    VBL routines are installed your  computer  will  do  nothing at all any
    more,  and  you'll have to reboot.

    The fact that the filelength is tested means that  you  may  not  pack,
    crunch and/or squeeze this file ...

    All the other options  and  possibilities  of  the  1.1 version are the
    same, except for the XBRA id,  which  is  now "NSC2".  The velocity has
    gone up to 97%. All the extras for  the 1.2 version lead to an extra of
    only 400 bytes.  The  size  of  this  accessory  is rather  ridiculous.
    N_SYSCOM takes  little more than 13K  of  your computers memory when it
    is installed.

    This program still is PD; I can take no responsibility for the (mis)use
    of it.


    Noud van Kruysbergen
    N.I.C.I.
    P.O. Box 9104
    6500 HE Nijmegen
    email:kruysbergen@hnykun53.bitnet
