Problem write to code space pic 18f452

[mister_e]

And another variant

        A = $1800
        hserout ["Writing...",13,10]
        For I = 0 To 7 step 2  
                D.highbyte =i
                d.lowbyte=d.highbyte+1
                Writecode A,D 
                HSEROUT [dec A, "=",dec D.highbyte, " ", dec d.lowbyte,13,10]
                a=a+2
                Next I
mainloop:
        hserout ["reading...",13,10]
        For a = $1800 To $1807 step 2 
                readcode A,D 
                HSEROUT [dec A, "=",dec D.highbyte, " ", dec d.lowbyte,13,10]
                Next