[Coco] Newbie help: Barden Bubble w/ Portal-9

[jimcox at miba51.com]

Hi all:

I entered the code below into a new file in Portal-9, set 
the file to be assembled as a single file, and the type of 
system to CoCo2 and MESS came up, but nothing runs.  Any 
pointers?

00100 * BUBBLE SORT
00110 BUBSRT CLR     PASSNO   SET PASS # TO 0
00120 BUB010 LDX     #$400       POINT TO SCREEN
00130        LDY     #0          SET CHANGEFLAG TO 0
00140 BUB020 LDA     ,X+            GET FIRST ENTRY
00150        CMPA    ,X             TEST NEXT
00160        BLS     BUB030         GO IF A<=B
00170        LDB     ,X             GET SECOND ENTRY
00180        STB     -1,X           SWAP B TO A
00190        STA     ,X             SWAP A TO B
00200        LDY     #1             SET "CHANGE"
00210 BUB030 CMPX    #$400+511      TEST FOR SCREEN END
00220        BNE     BUB020         GO IF NOT ONE PASS
00230        INC     PASSNO       INCREMENT PASS #
00240        CMPY    #0           TEST CHANGE FLAG
00250        BNE     BUB010       GO IF CHANGE OCCURRED
00260 LOOP   JMP     LOOP       LOOP HERE
00270 PASSNO FCB     0          PASS #
00280        END

I think it's something really stupid on my part.

Jim