;
; SCAN23BG.Z80 - 09/10/90
;
; This file is an overlay for SCAN23.COM that modifies the
; command table and command help screen for BGii compatibility.
; Note that these BGii commands prempt some of SCAN's default
; WordStar commands.  If you want both WordStar and BGii
; compatibility, you may have to experiment with the command set
; to get an acceptable mix.
;
; This overlay file cannot be used with earlier versions of SCAN!
;
; Assemble to a HEX file using Z80ASM, ZMAC, ZAS or ASM (rename
; to SCANBG23.ASM) and use MLOAD or MYLOAD to overlay the hex
; file on SCAN23.COM:
;
;       MLOAD SCAN.COM=SCAN23.COM,SCAN23BG.HEX
;
;
; Equates
;
BS      EQU     8               ; Backspace
TAB     EQU     9               ; Tab
LF      EQU     10              ; Line feed
CR      EQU     13              ; Carriage return
RETURN  EQU     13              ; Carriage return
ESC     EQU     27              ; Escape
SPACE   EQU     32              ; Space

; See SCAN23.PAT for more complete patching information for
; SCAN23.

;
; Command Customization
; ---------------------
;
; SCAN automatically capitalizes command characters when they are
; entered.  If entered commands are characters between A and Z,
; they are also made into control characters by subtracting 40h
; from them ('A'-40h = 01h, 'Z'-40h = 1Ah.)  Therefore, all
; command letters patched at the locations below must be patched
; as the capital letter - 40h.  All other command characters are
; used exactly as entered.
;
; Since a command letter may be entered with or without the
; control key being pressed, patching a command to 'E'-40h (^E
; or 05h) means, for example, that entering e, E or ^E gives the
; same result.
;
; When SCAN gets a command, it tries to match it with the command
; list, beginning at the bottom of the list (out of the patch
; area), in reverse order.  If you change a command to one that
; also appears lower in the list, the earlier use of the command
; will be automatically preempted, as the command search will end
; with the first match.  For example, attempting to use TAB to
; back up one page (at 289h) will be preempted by its original
; use to scroll the screen right (at 299h).
;
� Severa� functions hav� alternate� commands.  The second of these
; commands to be displayed in the help screen are marke� 
� (alternate-3chr)�  I� yo� patc� thes� command� t� b� SPACE� TAB� �
; ESC� CR� BS, etc� whic� wil� generat� 2-� character� i� th� hel� �
; scree� display� the� mus� appea� a� th� secon� comman� t� avoi� �
� overwritin� th� displa� o� th� firs� command� whic� i� assume� �
; t� b� displayed as one characte�.
;
; Commands modified for BGii compatibility, changed from
; SCAN's default commands to avoid conflict with other BGii
; commands, or because the original WordStar command may have
; been obscure to non-WordStar users are marked '(***BGii)',
; below.   See SCAN.PAT for the original command list.
;
      ORG     0281h     ; Command table patch area
;
;     Default   Location  Purpose
;================================================================
;
; WordStar default commands not appearing in help screen:
;
DB      'W'-40h ; 0281h ; Up (back) one line (WordStar)
DB      'E'-40h ; 0282h ; Up (back) one line (WordStar alternate)
DB      'Z'-40h ; 0283h ; Down one line (WordStar)
DB      'X'-40h ; 0284h ; Down one line (WordStar alternate)
DB      'S'-40h ; 0285h ; Display left (WordStar)
DB      'D'-40h ; 0286h ; Display right (WordStar)
DB      'C'-40h ; 0287h ; Down one page (WordStar)
DB      TAB     ; 0288h ; Up (back) one page (***BGii)
;
; Single-character commands automatically appearing in help screen:
;
DB      'B'-40h ; 0289h ; Top of file           (***BGii)
DB      'G'-40h ; 028Ah ; Find string           (***BGii)
DB      'E'-40h ; 028Bh ; Bottom of file        (***BGii)
DB      'A'-40h ; 028Ch ; Find again            (***BGii)
DB      'U'-40h ; 028Dh ; Cancel commands
DB      '<'     ; 028Eh ; Up (back) one page
DB      '>'     ; 029Dh ; Down (forward) one page
DB      CR      ; 0290h ; Down (forward) one page (alternate-3chr)(***BGii)
DB      '/'     ; 0291h ; Help/text toggle
DB	'?'	; 0292h ; Help/text toggle (alternate-3chr)
DB      ','     ; 0293h ; Up (back) one line
DB      'V'-40h ; 0294h ; Video mode toggle
DB      '.'     ; 0295h ; Down (forward) one line
DB      SPACE   ; 0296h ; Down (forward) one line (alternate-3chr)(***BGii)
DB      'P'-40h ; 0297h ; Printer toggle
DB      'L'-40h ; 0298h ; Scroll display left   (***BGii)
DB      'R'-40h ; 0299h ; Scroll display right  (***BGii)
DB      'C'-40h ; 029Ah ; Exit                  (***BGii)

;
; Return to Left Margin
; ---------------------
;
; The return to left margin character is the second character in
; the two-character WordStar 'quick' command '^QS', which returns
; the original left margin when you have been scrolling screen
; right.  Since BGii uses 'L' for the scroll left command, this
; command was changed to '^QL' for compatibility.  It does not
; appear in the help screen.
;
        ORG     2E2H    ; 'Q' prefix command
;
;     Default   Location  Purpose
;================================================================
DB      'L'-40h ; 02E2h ; Restore left margin (***BGii)

;================================================================
        END     ; Patch area