[Coco] Modifying Level1/coco1 for 6309 native mode

[Robert Gault]

Made some progress with a native 6309 code for the coco1. I can now get as far 
as a time entry request from setime. The screen waits for a key press and 
crashes on the first one.

To get this far, you need to edit rbf.asm looking for all the ,u entries. These 
will need to be compared to level2/rbf.asm and all pertinent entries changed to 
R$reg,u.

shortly after L02E9  change stx $06,u to stx R$X,u

Seek     ldb   $0A,y
          bitb  #$02
          beq   L037B
          lda   R$X+1,u        $05,u
          ldb   R$U,u          $08,u
          subd  $0C,y
          bne   L0376
          lda   R$X,u          $04,u
          sbca  $0B,y
          beq   L037F
L0376    lbsr  L0D72
          bcs   L0383
L037B    ldd   R$X,u         $04,u
          std   $0B,y
L037F    ldd   R$U,u         $08,u
          std   $0D,y
L0383    rts

L03BA    ldu   $06,y
          ldd   R$Y,u         $06,u
          subd  $02,s
          std   R$Y,u         $06,u
          bra   L040E
L03C4    ldd   R$Y,u         $06,u
          bsr   L03CD
          bcs   L03F1
          std   R$Y,u         $06,u
          rts

L0414    ldd   R$X,u         $04,u
          ldx   R$Y,u         $06,u

WriteLn  pshs  y
          clrb
          ldy   R$Y,u         $06,u
          beq   L0498
          ldx   R$X,u         $04,u
L0484    leay  -$01,y
          beq   L0498
          lda   ,x+
          cmpa  #$0D
          bne   L0484
          tfr   y,d
          nega
          negb
          sbca  #$00
          addd  R$Y,u        $06,u
          std   R$Y,u        $06,u
L0498    puls  y

Write    ldd   R$Y,u        $06,u

GetStat  ldb   R$B,u           $02,u
          cmpb  #SS.Opt
          beq   L0543
          cmpb  #$06
          bne   L052F
          clr   R$B,u           $02,u
L0529    clra
          ldb   #$01
          lbra  L03CD
L052F    cmpb  #SS.Ready
          bne   L0536
          clr   R$B,u           $02,u
          rts
L0536    cmpb  #SS.Size
          bne   L0544
          ldd   $0F,y
          std   R$X,u           $04,u
          ldd   <$11,y
          std   R$U,u           $08,u
L0543    rts
L0544    cmpb  #SS.Pos
          bne   L0551
          ldd   $0B,y
          std   R$X,u          $04,u
          ldd   $0D,y
          std   R$U,u          $08,u
Gst5FF   rts
L0551    cmpb  #SS.FD
          bne   SSFDInf
          lbsr  L0CD4
          bcs   L0543
          ldu   $06,y
          ldd   R$Y,u          was $06,u
          tsta
          beq   L0564
          ldd   #$0100
L0564    ldx   R$X,u          was $04,u

shortly after L05C6
          ldx   R$X,u          was $04,u

shortly after L0604
          lda   R$X+1,u        was $05,u


It is safe to say that there will be more level1 code which was disassembled 
without conversion to the R$reg format. When going from 6809 to native 6309 
code, the register stack changes and all $nm,u type code referring to registers 
can fail.

Robert