To:	ZCPR3 users with BackGrounder ii

From:	Bridger Mitchell and Jay Sage

Subject: BGii customization scripts

Date:	4/17/87

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Jay has contributed some excellent Z-system alias scripts for automating

the BGii startup and shutdown operations.  In addition, he shows how

to change the names of BGii built-in commands.  Useful in their own

right, these scripts are also a model of a well-designed system

environment.



You will need to modify the scripts to reflect your own system's

directory names and custom files.  The FIXBG addresses will vary,

depending on BGii version and the disk parameters of your swap drive.

And BGHIST and BGERRH require BGHIST.OCP.



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     Here are the ARUNZ (renamed to CMDRUN.COM) scripts I use for

the various BG-related operations.

 

1. script BG

 

   This script is used to engage BGii.  It goes to the required directory,

   clears the shell stack if necessary because BGii will invoke BGHIST, and

   then returns to the directory from which this alias was invoked.  The

   explicit directory references before some of the commands just speeds

   things up a little.

 

        SYS:                            ; Go to directory with LOADBG

        IF SH                           ; If a shell is currently running

        SYS:SHCTRL C                    ; Clear shell stack

        FI

        SYS:LOADBG                      ; Invoke BG (runs alias STARTBG)

        $D0$U0:                         ; Return to original directory

 

 

2. script STARTBG

 

   This script is the BGii startup alias.

 

        TIME ON                         ; Turn on time display in prompt

        KEYS GLOBAL                     ; Load my global key definitions

        OCP BGHIST                      ; Load OCP with BGHIST and BGERRH

         FIXBG (leading space)          ; Script to patch BG swap file

        BGHIST                          ; Load BG history shell

        BGERRH                          ; Engage BG error handler

        CLS                             ; Clear the screen

 

 

3. script FIXBG

 

   This script makes the changes to the BG swap file to rename some of the

   resident commands.  It could be a part of the main STARTBG script, but I

   prefer to keep this separate.  I change the ECHO command to ECKO so that

   my transient ECHO.COM, which runs at 8000H, will be used instead.  I also

   shorten PEEK to P and RESET to R.

 

        SYS:DU GF,+9,CA53 K,W,+,CA5A    ,CA7A     ,W,X

 

   Here are the operations performed by each of the disk utility commands:

 

        GF                      ; Go to disk group 000F (the group

                                ; ..containing the command dispatch table)

        +9                      ; Advance 9 records to the one containing

                                ; ..the entry for the ECHO command

        CA53 K                  ; Change-Ascii at byte 53H of the record,

                                ; ..putting in a 'K' in place of the 'H'

        W                       ; Write the changed record out to the disk

        +                       ; Advance to the next record on the disk

        CA5A....                ; Another Change-Ascii (note four spaces,

                                ; ..one to separate command from argument

                                ; ..and three to replace 'EEK' in 'PEEK'

        CA7A.....               ; Another change in same record (five spaces

                                ; ..in all, four to replace 'ESET' in

                                ; ..'RESET')

        W                       ; Write the changed record out to the disk

        X                       ; Exit from DU3 disk utility

 

   The actual records containg the command dispatch table varies with each

BGii release.  What has confused me a bit lately is the appearance in the

swap file of two command lists that each look like a dispatch table.  Only

one is, and the real table has to be determined by trial and error.

 

 

4. script BGOFF=OFF (two alternative names for same alias)

 

   This script exits from BGii and reestablishes the ZCPR system.  Since

   my configuration of BGii uses the RCP space, I have to restore the

   environment descriptor and the RCP code.

 

        IF BG                   ; If BG is currently running

        BG OFF                  ; BGii command to exit

        SYS:SHCTRL C            ; Clear shell stack (of BGHIST)

        SYS:LDR SYS.ENV,SYS.RCP ; Restore environment and RCP

        SYS:ERRSET SYS:VERROR   ; Set up ZCPR error handler

        ELSE                    ; Else if BG not running

        ECHO BG NOT RUNNING     ; Tell user

        FI

 

 

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