From news.csie.nctu.edu.tw!tsaiwn Sun Nov  6 09:57:11 1994
Path: news.csie.nctu.edu.tw!tsaiwn
From: tsaiwn@csie.nctu.edu.tw (Wen-Nung Tsai)
Newsgroups: csie.course.asm.a,csie.course.asm.b
Subject: source of HELLO.COM
Date: 4 Nov 1994 15:09:27 GMT
Organization: Dep. Computer Sci. & Information Eng., Chiao Tung Univ., Taiwan, R.O.C
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To make the following code usable, save this article into a file and
then use "vi" to remove the line numbers:
          :1,$s/^.......//        (這regular expression 共有七個點)
          :wq
Here it is:

     1		Title HWK03	- the source program
     2		assume cs:mycode,ds:mycode
     3	mycode	segment	public
     4		ORG	100h	; for .COM format
     5	Main	proc	near
     6		JMP short GO	; only for first RUN
     7		   ; in .COM, the data in program is not it's original form
     8		   ;=====================
     9		   ; Linkage instruction:
    10		   ; 	MASM file;
    11		   ;	LINK file;
    12		   ;	DEBUG file.exe
    13		   ;	- g
    14		   ;	-n file.com	; specify NAME to write
    15		   ;	-w
    16		   ;	-q		; quit
    17		;=============== another way after LINK file;
    18		;	EXE2BIN file file.com  (or LINK /tiny directly...)
    19		;	DEBUG file.com
    20		;	-g		; go
    21		;	-w		; write back to file.com
    22		;	-q	; it's done
    23		;===============
    24		MOV AL,[MAGIC]	; a magic number
    25		MOV AH,0eh	; write as teletype
    26		MOV CX,LENMSG	; Length of MSG as loop count
    27		LEA SI,MSG
    28	AGAIN:
    29		XOR	AL,CS:[SI]
    30		INT	10h	; to screen
    31		INC	SI	 ; next char
    32		LOOP	AGAIN    ; repeat until done(cx=0)
    33		MOV	AX,4c00h	; normal terminate
    34		INT	21h	; Bye
    35	MAGIC DB 38h
    36	MSG	DB 'Hello from Wen-Nung Tsai',10,13
    37	LENMSG = $ - MSG        ; the length of the above STRING
    38	GO:
    39		MOV ax,9090h	; NOP   /   NOP
    40		MOV WORD PTR CS:[MAIN],AX	; erase the JMP short GO
    41		LEA SI,MSG+LENMSG	; Si points to the last byte of MSG
    42		MOV CX,LENMSG	; Loop Count
    43	AGAIN2:
    44		DEC	SI	; backword
    45		MOV AL,CS:[SI]           ; Encode the data
    46		XOR AL,CS:[SI-1]         ;...
    47		MOV Byte PTR CS:[SI],AL
    48		LOOP	AGAIN2
    49		MOV CX,GO - Main	; the .COM program length
    50	                        ;..so that we can "w" into a file in DEBUG
    51		INT 3		; used in debug only 
    52	main	endP
    53	mycode	endS
    54		END	MAIN

--
--------------------------------------------
 Wen-Nung Tsai					蔡文能
 INTERNET:    tsaiwn@csunix.csie.nctu.edu.tw	Dep. of CSIE
 BITNET:      tsaiwn@twnctu01.bitnet		National Chiao Tung University
						HsinChu, Taiwan, R.O.C.