A86: Can somebody help me with this code?

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A86: Can somebody help me with this code?

I am nearly brand new as far as assembly programming- I'm trying to
teach myself from the few tutorials available and lookin at other
people's code.. It's pretty tough- I knwo Turbo pascal but this is WAY
different.. Anyways, I thought I'd try writing a routine to just move
a character around, allowing you to change the directions of it.. It
seems to me like this code should work, but what happens is this: It
seems to me, from some experimentation by inversing the video, and
then moving the un-inverse command around to pinpoint the problem,
that the program just exits at the end of the Display: fuinction.. It
doesn't return back to the function it's called from. 
Could somebody maybe give me some insight on this one? Any comments
are appreciated.

here's the code:

#include "asm86.h"
#include "ti86asm.inc"
#include "ti86math.inc"
#include "ti86ops.inc"
#include "ti86abs.inc"

.org _asm_exec_ram

        call _clrScrn
        ld bc,$0202
        set textInverse,(iy+textflags)
                     
Right:
        inc b
        jp Display
        jp CheckEdges
        jp CheckKeys
        jp Right

Left:
        dec b
        jp Display
        jp CheckEdges
        jp CheckKeys
        jp Left

Up:
        dec c
        jp Display
        jp CheckEdges
        jp CheckKeys
        jp Up

Down:
        inc c
        jp Display
        jp CheckEdges
        jp CheckKeys
        jp Down

CheckKeys:
        call _getkey
        cp kRight
        jp z,Right
        cp kLeft
        jp z,Left
        cp kUp
        jp z,Up
        cp kDown
        jp z,Down
        cp kExit
        jp z,Leave
        ret

CheckEdges:
       ;push af         ;if needed
        ld a,$00
        cp b
        jp z,ResetLeft
        cp c
        jp z,ResetTop
        ld a,$14
        cp b
        jp z,ResetRight
        ld a,$07
        cp c
        jp z,ResetBottom
       ;pop af
        ret

ResetLeft:
       ;jp Display
        ld b,$15
        ret

ResetRight:
       ;jp Display
        ld b,$00
        ret

ResetTop:
       ;jp Display
        ld c,$08
        ret

ResetBottom:
       ;jp Display
        ld c,$00
        ret

Display:
       ;push af
        ld a,$058
        ld (_curRow),bc
        call _putmap
       ; res textInverse,(iy+textflags)        PROBLEMS RIGHT HERE! i
think..
       ;pop af
       ; ret
       ; jp Right                   ; <-- Thought I'd force it to ;

                                        ;return to the loop it was

			;called from. This just simply crashed the
calculator..
;        res textInverse,(iy+textflags)

.end


I know certain areas like the checkedges routine won't work very well,
and I know it'll leave a trail right now. I'm just messing around, and
am completely stumped!!

Thanks,
Rolf
References: