====================================
Project #02 - Relocation and Linking
=====================================
- Ian! D. Allen - idallen@idallen.ca - www.idallen.com

Link the four modules together into memory in this order:
   START, PAUSE, MAIN, DBLE.

ANSWER:

The source files for the three modules contain some local (non-public)
labels with the same name, i.e. Count and One.  An LMC linker would
not see these private duplicate labels because they don't appear in
the object code files, but if you combine all the source code into one
big source file and try to assemble it, an LMC assembler program would
find that the duplicate labels conflict.  (You can't have two different
memory locations with the same label name.)  I've renamed some of the
labels in the module source below to make them all unique in the combined
source file.  Your submitted source may or may not do this, but you must
ensure that the LMC machine code for each module references its *own*
local label, not the label in another module.  (When MAIN references the
local label "Count", it must be the "Count" in the MAIN module, not the
"Count" in the PAUSE module, and vice-versa.)

I've also replaced the operands that use label mathematics
(e.g. "Pause-1") with plain lables (e.g. "PRet") below, since the LMC
assembler that I use to test code doesn't understand label math yet.
Your code can do it either way.

* Label Table (optional) *

PRET     at 06
PAUSE    at 07
PCOUNT   at 13
PONE     at 14
MRET     at 15
MAIN     at 16
COUNT    at 31
ONE      at 32
MAX      at 33
DRET     at 34
DBLE     at 35
ARG      at 38

Loc Code: Label   Opcode Operand       Comments

        : ; start (new MAIN program)
 00 500 :         IN
 01 231 :         STO Count
 02 500 :         IN
 03 233 :         STO Max
 04 016 :         CALL Main
 05 700 :         HLT
        : 
        : ; Pause subroutine (no input; no output)
 06 000 : PRet    DAT
 07 113 : Pause   LDA  PCount
 08 414 :         SUB  POne
 09 213 :         STO  PCount
 10 801 :         SKZ
 11 907 :         JMP  Pause
 12 906 :         JMP  PRet
 13 000 : PCount  DAT  000
 14 001 : POne    DAT  001
        : 
        : ; Main subroutine (inputs: Count and Max)
 15 000 : MRet    DAT
 16 131 : Main    LDA Count
 17 600 :         OUT
 18 007 :         CALL Pause
 19 131 :         LDA  Count
 20 238 :         STO  Arg
 21 035 :         CALL Dble
 22 600 :         OUT
 23 007 :         CALL Pause
 24 131 :         LDA  Count
 25 332 :         ADD  One
 26 231 :         STO  Count
 27 433 :         SUB  Max
 28 802 :         SKP
 29 916 :         JMP  Main 
 30 915 :         JMP  MRet    ; this must *not* be HALT (700)
 31 000 : Count   DAT  000
 32 001 : One     DAT  001
 33 010 : Max     DAT  010
        : 
        : ; Dble subroutine (no output; returns result in calculator)
 34 000 : DRet    DAT
 35 138 : Dble    LDA  Arg
 36 338 :         ADD  Arg
 37 934 :         JMP  DRet
 38 000 : Arg     DAT