10 ;WOBBLER
20 ;By Andy Guillaume
30 ;March 1996 for NAU
40 ;
50 XITVBI=49378    ;VBI Exit to DS
60 WSYNC=54282     ;Wait for SYNC reg
70 HSCROL=54276    ;Horiz Scroll reg
80 *=1536
90 CLINE *=*+1     ;Line counter
0100 TIMER *=*+1   ;VBI Timer Counter
0110 RTIME *=*+1   ;VBI Timer Reset
0120 CURRENT *=*+1 ;Pointer into DATA
0130 MAXIMUM *=*+1 ;Number of DATA
0140 SCT *=*+24    ;Scroll table
0150 DLI
0160   PHA        ;Push A
0170   TXA        ;X into A
0180   PHA        ;Push A
0190   LDX CLINE  ;Get line number
0200   LOA SCT,X  ;Get scroll byte
0210   5TA WSYNC  ;Wait for SYNC
0220   STA HSCROL ;Update scroll reg
0230   INC CLINE  ;Next line
0240   PLA        ;Pull A
0250   TAX        ;A into X
0260   PLA        ;Pull A
0270   RTI        ;Return from DLI
0280 VBI
0290   PHA        ;save A and X sane
0300   TXA        ;as DLI does
0310   PHA
0320   LOA #8     ;8 into A
0330   STA CLINE  ;Reset line number
0340   DEC TIMER  ;Decrease Timer
0350   BNE EXIT   ;If t<>0 then EXIT
0360   LOA RTIME  ;Get Timer Reset
0370   STA TIMER  ;Store at counter
0380   LDX #22    ;22 bytes to copy
0390 COPYLOOP
0400   LDA SCT,X	;Get byte
0410   STA SCT+1,X	;store in next loc
0420   DEX              ;Decrement X
0430   BPL COPYLOOP     ;If >-1 then LOOP
0440   LDX CURRENT      ;Get DATA pointer
0450   LOA DATA,X       ;Get byte
0460   STA SCT          ;Store in tine 8
0470   INC CURRENT      ;Increase pointer
0480   LOA CURRENT      ;Get pointer
0490   CMP MAXIMUM      ;At last line?
0500   BNE EXIT         ;If No then EXIT
0510   LOA #8           ;8 into A
0520   STA CURRENT      ;Reset pointer
0530 EXIT
0540   PLA              ;Restore A and X
0550   TAX              ;as before
0560   PLA
0570   JMP XITVBI       ;Continue OS VBI
0580 DATA *=*+1         ;Store for DATA