===================
ASM and VAL Example
===================
-IAN! idallen@ncf.ca

Here's an example of assembling some files downloaded to my C:\ directory.

I start up a DOS window in that directory, and type this to assemble
and link the file "noecho.asm" in the current directory:

    C:\>asm
    Arrowsoft Assembler
    Public Domain v2.00c (64K Model)
    Copyright (c) 1986, 1987 Arrowsoft Systems, Inc.

    Input filename  (.asm): noecho
    Object filename (noecho.obj):
    Listing filename(nul.lst):
    Cross-reference (nul.crf):
    Free memory=50996, Warnings=0, Errors=0

    Assembly Ended.

    C:\>val /com
    VAL 8086 linker - Mar 27 1995
    OBJ file(s):  noecho
    COM file[C:\noecho.com]:
    LST file:
    LIB file(s):

    C:\>noecho

    Bark! Bark! Bark! Ended on: d

    C:\>

I recommend using the command lines given at the start of ONEPAGE.ASM,
since that cuts down on the unnecessary verbosity.  Here is the same
assembly and link, using command line options and file names to remove
all the unnecessary verbosity:

    C:\>asm /s noecho ;

    C:\>val /com noecho ;

    C:\>noecho

    Bark! Bark! Bark! Ended on: d

    C:\>

Here are all the files:

    C:\>dir noecho.*

     Directory of C:\

    NOECHO   OBJ           146  07/07/00  12:28 NOECHO.OBJ
    NOECHO   ASM         2,396  07/07/00  12:21 noecho.asm
    NOECHO   COM            69  07/07/00  12:28 NOECHO.COM
	     3 file(s)          2,611 bytes

    C:\>

And, for your education and amusement, here's a DEBUG dump of the
assembled NOECHO.COM program memory, using DEBUG's "U" (UnAssemble)
command to turn the machine code in the *.COM file back into assembler
mnemonics (you can try doing this yourself):

    C:\>debug noecho.com
    -u
    1353:0100 C606410178    MOV     BYTE PTR [0141],78
    1353:0105 90            NOP
    1353:0106 803E410164    CMP     BYTE PTR [0141],64
    1353:010B 7409          JZ      0116
    1353:010D B407          MOV     AH,07
    1353:010F CD21          INT     21
    1353:0111 A24101        MOV     [0141],AL
    1353:0114 EBF0          JMP     0106
    1353:0116 BA2301        MOV     DX,0123
    1353:0119 B409          MOV     AH,09
    1353:011B CD21          INT     21
    1353:011D B000          MOV     AL,00
    1353:011F B44C          MOV     AH,4C
    -u
    1353:0121 CD21          INT     21
    1353:0123 0D0A42        OR      AX,420A
    1353:0126 61            DB      61
    1353:0127 726B          JB      0194
    1353:0129 2120          AND     [BX+SI],SP
    1353:012B 42            INC     DX
    1353:012C 61            DB      61
    1353:012D 726B          JB      019A
    1353:012F 2120          AND     [BX+SI],SP
    1353:0131 42            INC     DX
    1353:0132 61            DB      61
    1353:0133 726B          JB      01A0
    1353:0135 2120          AND     [BX+SI],SP
    1353:0137 45            INC     BP
    1353:0138 6E            DB      6E
    1353:0139 64            DB      64
    1353:013A 65            DB      65
    1353:013B 64            DB      64
    1353:013C 206F6E        AND     [BX+6E],CH
    1353:013F 3A20          CMP     AH,[BX+SI]
    -u
    [...etc...]
    -q

    C:\>

You will note that, as I've been saying, all the labels are missing
from the *.COM file - all we have are the machine instructions.  Also,
DEBUG doesn't know which bytes are instructions and which are data, so
it tries to turn everything into instruction mnemonics, even the data.

As you see from our instruction "MOV DX,0123", our BARKMSG string starts
at offset 0123h, so everything from memory offset 0123 onward is actually
data, not instructions.  Some of that data just happens to have the same
bit patterns as instructions, and DEBUG tries to display it as such.