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Antic Magazine 1988 February
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Antic_Magazine_1988_02_Antic_Side_A.atr
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fastjump.m65
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2023-02-26
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0100 ; FAST JUMP¢0110 ; BY BILL BODENSTEIN¢0120 ; (c)1987, ANTIC PUBLISHING¢0130 ;¢0140 ; EQUATES¢0150 ;¢0160 PORTB = $D301 ;Toggle ROM here¢0170 BASIC.ON = 253¢0180 ;¢0190 JSR = 32 ;Decimal opcodes¢0200 NOP = 234¢0210 STMTAB = $88 ;Start of prog¢0220 STMCUR = $8A ;Current line¢0230 FORLN = $A0 ;Lnno saved here¢0240 ;¢0250 PUT.PATCH = $A000 ;Mem for patch¢0260 JSR.HERE = PUT.PATCH+6 ;Actual¢0270 ; code¢0280 ;¢0290 *= $0600 ;Relocatable but¢0300 ; could be called¢0310 ; via USR(1536)¢0320 STARTCODE¢0330 PLA ;Remove # args¢0340 ;¢0350 ;Before searching for line,¢0360 ;jump to patch.¢0370 MODIFY.BASIC¢0380 LDA #JSR ;JSR PATCH¢0390 STA $A9AA¢0400 LDA # <JSR.HERE¢0410 STA $A9AB¢0420 LDA # >JSR.HERE¢0430 STA $A9AC¢0440 LDA #NOP ;NOP¢0450 STA $A9AD¢0460 ;¢0470 ;Install patch in unused (except¢0480 ;with NEW) BASIC RAM.¢0490 LDX #ENDCODE-PATCH-1¢0500 LDY #ENDCODE-STARTCODE-1¢0510 LOOP¢0520 LDA ($D4),Y ;Move bytes from¢0530 STA PUT.PATCH,X ;USR code¢0540 DEY ¢0550 DEX ¢0560 BPL LOOP ;Done when patch¢0570 RTS ;installed¢0580 ;¢0590 ;Patch to be installed in BASIC¢0600 ;RAM. If NEW occurs, BASIC ROM¢0610 ;is enabled so that patch isn't¢0620 ;accidently executed.¢0630 ;(Remember: With FAST-STACK, ROM¢0640 ;is always enabled in direct¢0650 ;mode.)¢0660 PATCH¢0670 NOP ¢0680 LDX #BASIC.ON¢0690 STX PORTB¢0700 ;¢0710 LDY #1 ;Is lnno >= curr¢0720 LDA FORLN+1 ; lnno???¢0730 CMP (STMCUR),Y¢0740 BCC NORMAL¢0750 BNE FAST¢0760 ;¢0770 DEY ¢0780 LDA FORLN¢0790 CMP (STMCUR),Y¢0800 BCC NORMAL¢0810 ;¢0820 FAST¢0830 LDA STMCUR+1 ;Yes,start from¢0840 LDY STMCUR ; current line¢0850 RTS ¢0860 NORMAL¢0870 LDA STMTAB+1 ;No,start from¢0880 LDY STMTAB ; first line¢0890 RTS ¢0900 ENDCODE¢
