0100 ;BUTTERFINGERS›0110 ;BY KEVIN C. GEVATOSKY›0120 ;(c)1989, ANTIC PUBLISHING INC.›0130 ;›0140 DOSINI = $0C›0150 VKEYBD = $0208  ;KB int. vector.›0160 KBCODE = $D209  ;Current key.›0170 CH1 =   $02F2   ;Prior key.›0180 CH  =   $02FC   ;Last key.›0190 SH_CLR = 118    ;Key codes.›0200 CT_CLR = 182›0210 CT_SH_CLR = 246›0220 ;›0230     *=  $0600›0240 ;›0250 ;This program provides two entry›0260 ;points so that it can be›0270 ;started from DOS or BASIC.›0280 ;›0290 START›0300     JMP INIT    ;For DOS entry.›0310     NOP         ;For BASIC entry›0320     PLA         ;w/ X=USR(1540)›0330 ;›0340 ;Makes the program RESET-proof›0350 ;›0360 INIT›0370     LDA DOSINI  ;Get current DOS›0380     STA NEW_INI+1 ;init address›0390     LDA DOSINI+1 ;and save in›0400     STA NEW_INI+2 ;new vector.›0410     LDA # <NEW_INI ;Put addr of›0420     STA DOSINI  ;new vector in›0430     LDA # >NEW_INI ;old vector.›0440     STA DOSINI+1›0450     BNE SET_KBVEC ;(JUMP)›0460 ;›0470 NEW_INI›0480     JSR $FFFF   ;New DOS init.›0490 ;›0500 ;Jump here on initialization or›0510 ;RESET to setup a new keyboard›0520 ;trap vector.›0530 ;›0540 SET_KBVEC›0550     SEI         ;Kill IRQ's.›0560     LDA VKEYBD  ;Save system KB›0570     STA SYSKBV  ;interrupt addr›0580     LDA VKEYBD+1 ;replace w/the›0590     STA SYSKBV+1 ;addr to our›0600     LDA # <KEY_TRAP ;key-trap›0610     STA VKEYBD  ;routine.›0620     LDA # >KEY_TRAP›0630     STA VKEYBD+1›0640     CLI         ;Restore IRQ's.›0650     RTS ›0660 ;›0670 ;Interrupt routine to replace›0680 ;SHFT+CLEAR and CTRL+CLEAR›0690 ;with SHFT+CTRL+CLEAR.›0700 ;›0710 KEY_TRAP›0720     PHA ›0730     LDA KBCODE  ;Get current key›0740     CMP #SH_CLR ;Filter out the›0750     BEQ GOT_YA  ;standard clear›0760 ;›0770     CMP #CT_CLR ;screen keys.›0780     BEQ GOT_YA›0790 ;›0800     CMP #CT_SH_CLR ; Check for›0810     BNE GO_KB_INT ;  our special›0820 ;                    key›0830 CLR_SCR ;       combination›0840     LDA #SH_CLR›0850     STA CH      ;Put clr-screen›0860     STA CH1     ;code for Editor›0870 GOT_YA›0880     PLA         ;Return from the›0890     PLA         ;interrupt.›0900     RTI ›0910 ;›0920 GO_KB_INT›0930     PLA         ;Pass all other›0940     JMP (SYSKBV) ;keys on to OS›0950 ;›0960 SYSKBV›0970     .DS 2       ;keybd handler.›0980     *=  $02E0   ;DOS RUN address›0990     .WORD START›1000     .END ›