;=========================================
; LMC Sample Program #1 - add and subtract
;=========================================
; - Ian! D. Allen - idallen@idallen.ca - www.idallen.com
;
; We will use this 6-column format for all LMC programs.
; (We won't use the Label column yet.)
; Start by filling in the Mnemonic and Operand columns, then go back
; and "hand-assemble" the mnemonics into actual numbers in mailboxes.
;
; The "DAT" (data) mnemonic is not an LMC instruction.  It is used by
; assembly language programmers to indicate that the given operand is data
; to be placed in memory at the current memory location.
;
; The "ORG" (origin) mnemonic is not an LMC instruction.  It is used by
; assembly language programmers to indicate that the next instructions
; or data will be placed into memory starting at the given address.
;
; Note that the Negative light will come on after the subtraction.
; It will go off after the addition, because only subtracting a big
; number from a small number sets the Negative light.  Addition can
; never set the Negative light.
;
; Output: 7 - 15 + 2 = 994 (using 3-digit odometer math; no negative numbers)
;
;Loc.   Code    Label   Mnemon. Operand Comments
;----   ----    -----   ------- ------- -------------------------
00      162             LDA     62      ; load first number
01      463             SUB     63      ; subract second number
02      364             ADD     64      ; add third number
03      600             OUT             ; output result
04      700             HLT             ; put LMC to sleep (stop execution)
                        ORG     62      ; place next data starting at box 62
62      007             DAT     007     ; first number (constant)
63      015             DAT     015     ; second number (constant)
64      002             DAT     002     ; third number (constant)

; Note that this program could have been written this way, though it is
; much harder to read since no helpful mnemonics are used:
;
;Loc.   Code    Label   Mnemon. Operand Comments
;----   ----    -----   ------- ------- -------------------------
00      162             DAT     162     ; load first number
01      463             DAT     463     ; subract second number
02      364             DAT     364     ; add third number
03      600             DAT     600     ; output result
04      700             DAT     700     ; put LMC to sleep (stop execution)
                        ORG     62      ; place next data starting at box 62
62      007             DAT     007     ; first number (constant)
63      015             DAT     015     ; second number (constant)
64      002             DAT     002     ; third number (constant)