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assembly language
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Language Assembler (motorola 6809)
(used in the CBM Pet, and the Dragon 32)
| Date: | 08/16/07 |
| Author: | Rik Hughes |
| URL: | http://www.rikaitch.plus.com |
| Comments: | 1 |
| Info: | http://en.wikipedia.org/wiki/Motorola_6809 |
| Score: |  (3.53 in 145 votes) |
c:\meta\i\6809/ intel title "99 bottles of beer" .tab 8,8,8,80 ; public bottlebeer ; segment 'ram' tmp ds.b 1 ; segment 'eprom' ; ;*** 99 bottles of Beer ;*** Rik Hughes, 16/08/2007 ;*** written for the intel 6809 cpu ; bottlebeer: bbeer0: ldab #99 bbeer1: ldx #0 tstb beq bbeer2: jsr shwnum ; show number of bottles left bra bbeer3 bbeer2: ldx #notxt ; 0 = "no" jsr shwtxt bbeer3: ldx #btltxt ; bottle jsr shwtxt cmpb #1 beq bbeer4 ldaa #'s' ; not 1, then show an 's' bbeer4: ldx #bertxt ; "of beer" jsr shwtxt ldx #waltxt ; "on the wall" jsr shwtxt ldx #crtxt ; do a cr jsr shwtxt bbeer5: ldx #0 tstb beq bbeer6: jsr shwnum ; show number of bottles left bra bbeer7 bbeer6: ldx #notxt ; 0 = "no" jsr shwtxt bbeer7: ldx #btltxt ; bottle jsr shwtxt cmpb #1 beq bbeer8 ldaa #'s' ; not 1, then show an 's' bbeer8: ldx #bertxt ; "of beer" jsr shwtxt ldx #crtxt ; do a cr jsr shwtxt tstb ; is it 'no bottles of beer?' beq bbeer9 ldx #pastxt ; "take one down, pass it around" \n jsr shwtxt decb ; lose a bottle bra bber10 bbeer9: ldx #mortxt bber10: bra bbeer0 ; go back to the start rts ; show 2 digit number stored in x shwnum: pshs a ; preserve accumulator pshs x ldx #10 pshs x jsr div16 ; divide x on stack by 10 puls a ; get result puls a ; remembering to forget high byte tsta ; is it 0? beq shwnm1 ; yes, so don't display it. staa stdout ; display 10's shwnm1: puls a ; get remainder puls a staa stdout ; display units always puls a ; restore accumulator ;show text string stored in x shwtxt: pshs b ;preserve register clr b ;reset pointer shwtx1: pshs x ;preserve address of text puls x abx ;get pointer in text lda 0,x beq shwtx2 staa stdout ;display char incb bra shwtxt1 ;move to next char shwtxt2 puls b rts ; ;*** Divide two sixteen bit values on the system stack ; div16: pshs d,x tfr s,x ldx 8,x ; get dividend pshs x ldx #0 pshs x lda #16 tfr s,x div162: rol 13,x rol 12,x rol 1,x rol 0,x pshs a ldd 0,x subd 10,x bcs div161 std 0,x div161: puls a deca bne div162 rol 13,x rol 12,x com 13,x com 12,x ldd 0,x std 10,x puls x puls x puls d,x,pc .btltxt dc.b "bottle",0 .bertxt dc.b " of beer",0 .waltxt dc.b " on the wall",13,10,0 .notxt dc.b "no ",0 .pastxt dc.b "take one down, pass it around,",13,10,0 .crtxt dc.b 13,10,0 .mortxt dc.b "Go to the store and buy some more,",13,10,0 end
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