; FIRST.ASM
;
; A sample of how to include and call routines in the dec_IO.pkg
; The dec_IO.pkg was written by Alan Pinck.
;
; This file may be assembled and linked using the freeware ASM assembler
; and VAL linker available at:
;
;   ftp://ftp.algonquincollege.com/pub/infosystems/pincka/dat2343/arrowasm
;
; These are the command lines I used (note the trailing semicolons):
;
;       C:> asm /s first ;
;       C:> val /co first ;
;
;  - Using a semicolon as an argument suppresses all the prompts
;    for output files and uses the defaults.  (See the documentation.)
;  - The /s option to ASM suppresses unnecessary verbosity.
;  - The /co option to VAL creates a ".COM" file (instead of a ".EXE")
;
;       C:> first
;       This is my first Intel ASM program.
;
;       12345
;       26708
;       26708
;       C:>
;
;  You can examine and trace the resulting executable .COM file using debug:
;
;       C:> debug first.com
;       -u100
;       1454:0100 BA2201        MOV     DX,0122
;       1454:0103 B409          MOV     AH,09
;       1454:0105 CD21          INT     21
;       ... etc ...
;
; -IAN! idallen@ncf.ca  November 1999
;
;-------------------------------------------------------------------
Ian     segment
        assume  CS:Ian,DS:Ian
        org     100h            ; .COM requires this
;-------------------------------------------------------------------
start:
        ; Print a message.
        ;
        mov     dx,offset msg   ; offset address of the message text
        mov     ah,09h          ; code for "display ASCII$ string"
        int     21h             ; Note: don't forget the 'h' on 21h!

        ; Display a number using the I/O package "shownum" procedure.
        ; (Read the comments in the I/O package to know how to use
        ; each of the I/O functions.)
        ;
        mov     ax,12345        ; Note: no 'h' - this number is decimal
        call    shownum

        ; Load the first two ASCII bytes of msg as if they were a number
        ; and print the number (in decimal).
        ;
        mov     bx,offset msg   ; load offset address of the message text
        mov     ax,[bx]         ; pick up into AX 2 bytes at that address
        call    shownum

        ; Explicitly set the AX register to be the same two bytes
        ; and print the number again.  See!  It's the same!
        ;
        mov     al,"T"          ; first byte in low half of AX
        mov     ah,"h"          ; second byte in high half of AX
        call    shownum

        ; Quit the program (return to the O/S).
        ;
        mov     al,0h           ; load a successful return status
        mov     ah,4Ch          ; code for "terminate program"
        int     21h
;-------------------------------------------------------------------
; I put my data and variables down here.
; Note that labels on data do *NOT* have colons!
; (Labels on program instructions *DO* need colons.)
; 
msg     db      "This is my first Intel ASM program."
        db      0Dh,0Ah         ; CR, LF
        db      "$"             ; end of ASCII$ string
;-------------------------------------------------------------------
        include dec_IO.pkg      ; include source for Alan's I/O package here
Ian     ends
        end start               ; "start" is the label on the first instruction