;--------------------------------------------------------------------
      ; Here is your "Writing My First Program to Toggle into the Imsai
      ; 8080 (meaning the Z80Pack Frontpanel Imsai 8080 Emulator)
      ; Written by Lawrence Woodman on 5th November 2008 Techtinkering.com
      ; -------------------------------------------------------------------
      ; Your program listing reformatted 7 September 2010 by Alan Spicer -
      ; in an attempt to make the program reloadable by this simulator 
      ; without having to toggle the whole thing in every time!
      ; -------------------------------------------------------------------
      ; Which brings us to ... how can we save it so it can be loaded?
      ; The simulator will take "-xFILENAME" to load a hex or bin file
      ; and thus can load it at program run (Power On) and execute it with
      ; almost no toggle switching at all. But how do we make a hex or bin
      ; file out of this thing? We copy and paste your SOURCE listing ...
      ; run it through a BUNCH of Unix/Linux utilties to try and get an
      ; Assembly Language Source File that *something* near to this sim
      ; can compile into bin or hex files. And so I did...
      ; -------------------------------------------------------------------
      ; I found out that there is Z80ASM that Udo Munk wrote that comes
      ; with Z80pack, and also Z80ASM for Linux available elsewhere.
      ; Which one will win the prize first and compile without tons of
      ; fatal errors? Udo Munk's Z80asm won the prize. But not without a
      ; lot more work from me. Neither Z80ASM would take 8080 Assembler
      ; code, which is what Lawrence wrote this in. They wanted Z80
      ; Assembler Mnemonics and ways of doing things. So off to a trans-
      ; lator near you to try and switch it over. Lots more Unix utils
      ; used to switch things over, like the VI Editor.
      ; 
      ; It also seemed that the Z80asm didn't like certain length of
      ; LABELS in the program source code. They were not unique, it said.
      ; So fix that. And I still have 4 errors but it did compile to
      ; binary code. Both bin and hex files could be created. And they
      ; were. But something still seems to be wrong. The machine code
      ; that is generate does load into the sim machine. But it does not
      ; yet run. There still seems to be some bugs in a few spots where
      ; the Z80 machine code did NOT EQUAL the 8080 code? Or the hand
      ; code that you made? Did you really do this with no assembler?
      ; It's awful strange how you came out with such a listing????
      ;-------------------------------------------------------------------
      ; After much work re-assembling and trying to fix those errors -
      ; I finally figured out how to kill those 4 errors. 2 each were
      ; the same, The assembler seems to like "FF" in "00ffh" format,
      ; and the IN and OUT data, also "FF"'s had to be in parenthesis.
      ; Imagine all of that???? It loads ok now from a HEX file and
      ; your program works. The bin file? I might be still doing something
      ; wrong with that. But this has been a LONG NIGHT/MORNING.
      ;-------------------------------------------------------------------


        ORG     0
;
      ;-----------------------------------
      ; Initialise the register variables
      ;-----------------------------------
;
        LD     C,00FFh
        LD     D,1
;
      ;-----------------------------------------
      ; Move the recorded position of the light
      ;-----------------------------------------
;
LOOP:   LD     A,D                   ; Load Position into Accumulator
        CP     128 
        JP     Z,SWDIR               ; Position = 128?
        CP     1 
        JP     NZ,MOVEPOS            ; Position != 1?
;
      ; Switch the direction of the light
;
SWDIR:  LD     A,C                   ; Load Direction into Accumulator
        CPL                          ; Compliment the accumulator
        LD     C,A                   ; Store result back in the Direction
MOVEPOS:LD     A,C                   ; Load Direction into Accumulator
        CP     0                     ; Direction != left?
        JP     NZ,MOVERT 
;
      ; Move position Left
;
        LD     A,D                   ; Load Position into Accumulator
        RLA                          ; Rotate left
        LD     D,A                   ; Store result back in the Position
        JP     OUTPLGHT 
;
      ; Move position Right
;
MOVERT: LD      A,D                  ; Load Position into Accumulator
        RRA                          ; Rotate right
        LD     D,A                   ; Store result back in Position
;
      ;-----------------------------------------------
      ; Output the light to PROGRAMMED OUTPUT display
      ;-----------------------------------------------
;
OUTPLGHT:    LD      A,D             ; Load Position into Accumulator
        CPL                          ; Compliment Accumulator due
                                     ; to way PROGRAMMED OUTPUT works
        OUT     (00FFh),A            ; Output to PROGRAMMED OUTPUT
;
      ;-----------------------
      ; User controlled Delay
      ;-----------------------
;
        IN      A,(00FFh)            ; User delay from PROGRAMMED INPUT
                                     ; port 0xFF
        INC     A                    ; Make sure 0 is minimum delay
DLYOUTR:LD      B,02                 ; Set register B loop delay to 2
DLYINR1:LD      E,00FFh              ; Set register E loop delay to 255
DLYINR2:DEC     E                    ; Decrement Register E
        JP     NZ,DLYINR2            ; Loop until Register E = 0
        DEC     B                    ; Decrement Register B 
        JP     NZ,DLYINR1            ; Loop until Register B = 0
        DEC     A                    ; Decrement Accumulator
        JP     NZ,DLYOUTR            ; Loop until Register A = 0 
;
      ;-------------------
      ; Loop indefinitely
      ;-------------------
;
        JP     LOOP 

	END