1000 REM --- GARBAGE COLLECTOR MESSAGE ---
1010 REM ----- BY MICHAEL T. GRAHAM ------
1020 REM OPEN8,8,8,"0:GARBMSG,P,W"
1030 SYS700
1040 ;.OPT O8
1050 ;PAL ASSEMBLER SOURCE CODE
1060 ;
1070 ;THIS BASIC PATCH PUTS A MESSAGE
1080 ;ON SCREEN WHEN BASIC'S GARBAGE
1090 ;COLLECTOR RUNS. BASIC IS MOVED TO
1100 ;RAM AT INITIALIZATION.
1110 ;
1120 HIBASE =$0288 ;KERNAL SCREEN PAGE ADDR
1130 ADDR   =$FB   ;MOVE VECTOR
1140 PATCH1 =$B526 ;"PATCH START OF COLLECTOR
1150 PATCH2 [178]$B606 ;"PATCH END OF COLLECTTOR
1160 RET1   =$B52A ;CONTINUE START
1170 CONT   =$B60C ;(null)OR NOT DONE
1180 QUIT   =$B601 ;"END COLLECTION
1190 COL[176]  [178]$02   ;MESSAGE COL[176] S[164]RAGE
1200 CMEM   [178]$D80A ;COL[176] MEM[176]Y START
1210 SCREEN [178]$FD   ;SCREEN VEC[164]R S[164]RAGE
1220 ;
1230 [172][178]$033C ;CASSETTE BUFFER
1240 ;
1250 ;INITIALIZE MESSAGE PATCH ([158] 828)
1260 ;
1270 INIT LDA #$00   ;SET UP
1280 STA ADDR        ;INDIRECT
1290 LDA #$A0        ;ADDRESS
1300 STA ADDR[170]1      ;[164] MOVE
1310 LDY #$00        ;BASIC
1320 XFER LDA (ADDR),Y ;MOVE BASIC ROM
1330 STA (ADDR),Y    ;[164] RAM
1340 INY
1350 BNE XFER
1360 INC ADDR[170]1      ;BUMP PAGE ADDRESS
1370 LDA ADDR[170]1      ;[154]INUE MOVE
1380 CMP #$C0        ; UP [164]
1390 BMI XFER        ;$BFFF
1400 LDA #$4C        ;JMP INSTRUCTI[145] OP CODE
1410 STA PATCH1      ;S[164]RE THE JUMPS [129] THE
1420 STA PATCH2      ;PATCHES
1430 LDA #[179]FIX1      ;JUMP [164] FIX1 AT START
1440 STA PATCH1[170]1
1450 LDA #[177]FIX1
1460 STA PATCH1[170]2
1470 LDA #[179]FIX2      ;JUMP [164] FIX2 AT [128]
1480 STA PATCH2[170]1
1490 LDA #[177]FIX2
1500 STA PATCH2[170]2
1510 LDA #$EF        ;MAP
1520 STA $00         ;OUT
1530 LDA $01         ;THE BASIC
1540 [175] #$FE        ;ROM
1550 STA $01
1560 LDA #01         ;INITIALIZE
1570 STA COL[176]       ;COL[176] [164] WHITE
1580 RTS             ;[128] INIT
1590 ;
1600 ;PATCH H[175]LER
1610 ;
1620 ;FIX1 [178] PATCH [164] START OF [209][176]
1630 ;
1640 FIX1 JSR MS[203]N  ;DISPLAY MESSAGE
1650 LDX $37         ;FINISH DISPLACED BASIC
1660 LDA $38         ;CODE
1670 JMP RET1        ;[142] [164] BASIC
1680 ;
1690 ;FIX2 [178] PATCH [164] [128] OF [209][176]
1700 ;
1710 FIX2 LDA $4F    ;FINISH BASIC'S
1720 [176]A $4E         ;STUFF
1730 BEQ RETRN       ;D[145]E [209]I[145]
1740 JMP [154]        ;[154]INUE [209]I[145]
1750 RETRN JSR MS[203]FF ;PUT SCREEN BACK
1760 JMP QUIT        ;[209][176] D[145]E
1770 ;
1780 ;[148] USER SCREEN [175] PUT MESSAGE
1790 ;[145] SCREEN BE[129]E STARTING
1800 ;GARBAGE [209][176].
1810 ;
1820 MS[203]N PHP       ;[148] STATUS
1830 TYA             ;[175] Y
1840 PHA             ;REGISTER
1850 LDA #10         ;START AT
1860 STA SCREEN      ;11TH CHAR
1870 LDA HIBASE      ;[161] SCREEN
1880 STA SCREEN[170]1    ;PAGE ADDR
1890 LDY #19         ;20 CHARACTERS
1900 LDX COL[176]       ;MESSAGE COL[176]
1910 MOVE LDA (SCREEN),Y ;[148] EXISTING
1920 STA BUFFER,Y   ;SCREEN [154]ENTS
1930 LDA MESSAG,Y   ;[161] MESSAGE
1940 [175] #$BF       ;C[145]VERT [164] SCREEN CODE
1950 STA (SCREEN),Y ;DISPLAY MESSAGE
1960 LDA CMEM,Y     ;[148] EXISTING
1970 STA CBUFF,Y    ;COL[176] MEM[176]Y
1980 TXA            ;REPLACE WITH
1990 STA CMEM,Y     ;MESSAGE COL[176]
2000 DEY            ;BUMP INDEX
2010 BPL MOVE       ;MOVE 20 CHARACTERS
2020 PLA            ;[140]
2030 TAY            ;REGISTERS
2040 PLP
2050 RTS            ;D[145]E
2060 ;
2070 ;PUT USER'S SCREEN [154]ENTS BACK
2080 ;AFTER COLLEC[164]R IS D[145]E.
2090 ;
2100 MS[203]FF PHP     ;[148]
2110 PHA
2120 TYA            ;REGISTERS
2130 PHA
2140 LDA #10        ;11TH CHARACTER
2150 STA SCREEN     ;[145] SCREEN
2160 LDA HIBASE     ;SCREEN PAGE
2170 STA SCREEN[170]1   ;ADDRESS
2180 LDY #19        ;20 CHARACTERS
2190 RES[164]R LDA BUFFER,Y ;PUT TEXT
2200 STA (SCREEN),Y ;BACK
2210 LDA CBUFF,Y    ;[140]
2220 STA CMEM,Y     ;COL[176]S
2230 DEY            ;BUMP INDEX
2240 BPL RES[164]R     ;[140] 20 CHARACTERS
2250 PLA            ;[140]
2260 TAY
2270 PLA            ;REGISTERS
2280 PLP
2290 RTS            ;D[145]E
2300 ;
2310 MESSAG .[198] " >WAIT,SYSTEM BUSY< "
2320 ;
2330 ;[131] STORAGE - 40 BYTES AT $02A7
2340 ;
2350 [172][178]$02A7
2360 ;
2370 BUFFER [172][178][172][170]20
2380 CBUFF [172][178][172][170]20
2390 ;
2400 .[128]