Listing 3.  The essential material in the patch for
installing an internal environment into DU35.

; PROGRAM:	DU-CPM.Z80
; AUTHOR:	Jay Sage
; DATE:		June 15, 1991

; This code is a patch that can be used with DU35 to embed
; an internal environment descriptor and TCAP so that DU35
; can be used under standard CP/M (2.2 or 3) as well as Z-
; -System.  To use this patch, DU35.Z80 must be assembled as
; usual to a REL file and then linked with the data segment
; (DSEG) moved 100H higher in memory to provide a place to
; insert the ENV.  The appropriate linker commands with the
; version-4 libraries are as follows:
;
;	SLRNK DU35/N,/P:100,/D:2E50,DU35,
;	           VLIB/S,Z3LIB/S,SYSLIB0/S,/E
; or
;	ZML DU35,VLIB/,Z3LIB/,SYSLIB0/ D2E50
;
; This linking leaves the space from 2D50H to 2E4FH free for
; an internal ENV and TCAP, which are defined below in this
; patch.  As distributed, this patch is set up with an ENV
; for my Televideo 803H computer and a TCAP for a Wyse-50
; terminal (this works on the Televideo, too).  You should
; edit the file so that it describes your system (search for
; the sections marked with "***** USER EDIT *****".
;
; Once the patch has been edited, assemble it to a HEX file
; and then use MLOAD (or MYLOAD) to apply the overlay:
;
;	MLOAD DU=DU35.COM,DU-CPM.HEX

; An alternative way to install the TCAP is to extract a
; binary TCAP from one of the distribution files (such as
; Z3TCAP.TCP, which is a library collection of TCAPs)
; Then, after installing the DU-CPM patch, use a debugger or
; file editor to install the desired TCAP into DU.COM at
; address 2DD0H (on top of the one installed by this patch).

; -------------------------------------------------------

; System configuration information (***** USER EDIT *****)

	; OMITTED MATERIAL SAME AS THE CONFIGURATION
	; EQUATES IN CPMENV.LIB


intenv	equ	02d50h	; Place in DU35 for the internal ENV

; -------------------------------------------------------

; Install ENV address at beginning of code

	org	109h		; Place for the ENV address

	dw	intenv		; Internal ENV address

; -------------------------------------------------------

; Install the dummy ENV in the DU35 code

	org	intenv

	; OMITTED MATERIAL SAME AS THE MACRO CODE
	; IN CPMENV.LIB

;  End of NZTCAPD
                                                                                        