Subject :  IMP overlay customization
From    :  Irv Hoff
Date    :  17 July 85


        The following notes will help the IMP user to select various
user options.  The ones that should be quite self-explanatory will not
be included in the list.


0103  MSPEED    -  use 05 for 1200, 06 for 2400.
0104  HS2400    -  YES if 2400 is your top speed, otherwise NO
0105  HS1200    -  YES if 1200 is your top speed, otherwise NO
0106  RACAL     -  YES if using a Racal-Vadic modem with autodial
                        (the 1200v and 2400v can also use the Hayes
                        AT protocol, but the Racal-Vadic protocol
                        displays additional progress reports.)
                -  NO for "AT" protocol developed by Hayes
0107  PROMODM   -  YES if using the Prometheus ProModem 1200, else NO

010A  CLEAR     -  Most computers can clear the CRT with a CTL-Z, if
                   yours does, put a 1BH (CTL-Z) here.  Some use an
                   "ESC-x" (the "x" may be a upper or lower case ASCII
                   character.)  Put that character in this location, the
                   ESC will be automatically added if an ASCII character
                   is present.  Put a 0 here if you don't know what your
                   terminal needs, it will then scroll 24 blank lines to
                   clear the screen.
010B  CLOCK     -  This value is your clock speed times 10, for more
                   variation.  A 4 MHz clock would use 40.  (Convert to
                   hex if installing via DDT.)  This just sets the time
                   for some of the internal delay loops.  It can be
                   changed to whatever is needed to make those more ac-
                   curate.
010C  BYTDLY    -  This puts a delay between characters when sending an
                   ASCII file in the terminal mode.
010D  CRDLY     -  This puts a delay after a CRLF when sending an ASCII
                   file in the terminal mode.  Sometimes these are used
                   on systems that cannot accept messages at full speed.
010F  TCHPUL    -  Some modems (such as the Racal-Vadic, Prometheus,
                   etc.) can auto-sense if they can touch-tone dial or
                   need to pulse dial.  Put a 0 here (do not use '0'
                   which is an ASCII value) if you want your modem to
                   auto-sense what it can use.  Else a 'T' or 'P'.
0114  EXTCHR    -  This is the local control "lead-in" character when in
                   the terminal mode.  Currently set to ESC.  Some ter-
                   minals don't have ESC or the operator may prefer some
                   other character.  Put it here.

                   The characters from 0115 through 011C are the local
                   control characters and may easily be changed to suit
                   the operator's preference - if different.

0168  J$STRNGA  -  This jumps to the 'AT' initialization string for
                   1200 bps modems.
0169  J$STRNGB  -  This jumps to the 'AT' initialization string for
                   2400 bps modems.  If the user wants to develop his
                   own customized initialization string, just change
                   this to jump to your own routine.

                   In writing these routines, you can use J$ILPRT for
                   strings (terminate with a 0 character) for local
                   display, "CALL  J$CRLF" for a new line on the CRT,
                   J$SNDSTR to send a string to the modem (end with $),
                   J$SNDCHR to send a single character to the modem, and
                   '#' character is a 0.1 second delay.  Including ###
                   in the string to the modem would cause a 300 ms.
                   delay, etc.  (250 ms. minimum needed after an 'AT'
                   string is completed by a CR before the modem should
                   be given any other duty.)

                   The J$ commands just listed would allow the user to
                   add routines to set parity, stop bits, different
                   initialization strings, etc.

ROOM REMAINING
--------------
        There are 601 characters remaining after the start of the SYSVR
label.  The routines in the overlay should stop by 0400H.  In the case
of the I2DP-1 overlay, that would leave an additional 223 bytes for any
customization the user might add.
                                        - Irv Hoff
                                          Los Altos Hills, CA
                                          (415) 948-2166 - voice