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Now there's a listing of the program that contain the instruction to
read this format. The fields that depends by the particular game that are
loading are removed. Note that the format stores the ending address of
the program that will be loaded in this code, while the starting address
is always assumed as the default 0801h.
This program is also autostarting (see location 0302h) and the readed
file is automatically executed by a RUN instruction.
02BA 00 BRK 02BB 09 02BC 73 02BD A4 02BE A5 2B LDA $2B Pointer: Start of BASIC program 02C0 EA NOP 02C1 85 26 STA $26 Real product 02C3 AD 0C 03 LDA $030C 6502 A register memorization 02C6 85 63 STA $63 Floating point accumulator #1: Mantissa 02C8 AD 13 03 LDA $0313 Not used 02CB 85 62 STA $62 Floating point accumulator #1: Mantissa 02CD A5 2C LDA $2C Pointer: BASIC starting programs 02CF EA NOP 02D0 85 27 STA $27 Real product 02D2 20 61 03 JSR $0361 Routine: Read the program 02D5 20 15 FD JSR $FD15 Routine RESTOR of KERNAL 02D8 20 53 E4 JSR $E453 Routine: Set BASIC vectors (300h..309h) 02DB 20 33 A5 JSR $A533 BASIC ROM 02DE A5 62 LDA $62 Floating point accumulator #1: Mantissa 02E0 A6 63 LDX $63 Floating point accumulator #1: Mantissa 02E2 85 2D STA $2D Pointer: BASIC starting variables 02E4 86 2E STX $2E Pointer: BASIC starting variables 02E6 A9 52 LDA #$52 Key: 'R' 02E8 8D 77 02 STA $0277 Keyboard buffer queue (FIFO) 02EB A9 D5 LDA #$D5 Key shortcat of 'UN' 02ED 8D 78 02 STA $0278 Keyboard buffer queue (FIFO) 02F0 A9 0D LDA #$0D Key: return 02F2 8D 79 02 STA $0279 Keyboard buffer queue (FIFO) 02F5 A9 03 LDA #$03 02F7 85 C6 STA $C6 Number of char in keyboard buffer 02F9 4C 74 A4 JMP $A474 Routine: Write READY, start up 02FC EA NOP 02FD EA NOP 02FE EA NOP 02FF EA NOP 0300 BE 02 dw $02BE Vector: Write BASIC error messages 0302 BE 02 dw $02BE Vector: BASIC start up 0304 7C 01 dw $017C Vector: BASIC text "tokenized" 0306 14 A7 dw $A714 Vector: BASIC text list 0308 E4 A7 dw $A7E4 Vector: BASIC chars sending 030A 86 AE dw $AE86 Vector: BASIC "token" valutation 030C xx dw xx Hi address of ending program 030D 62 030E 00 030F 32 0310 4C 48 B2 JMP $B248 Routine: Write (ILLEGAL QUANTITY) error 0313 yy dw yy Lo address of ending program 0314 2C F9 dw $F92C Vector: Hardware Interrupt (IRQ) 0316 57 08 dw $0857 Vector: Break Interrupt 0318 E2 FC dw $FCE2 Vector: Not maskerable Interrupt (NMI) 031A 4A F3 dw $F34A KERNAL OPEN routine vector 031C 91 F2 dw $F291 KERNAL CLOSE routine vector 031E 0E F2 dw $F20E KERNAL CHKIN routine vector 0320 50 F2 dw $F250 KERNAL CHKOUT routine vector 0322 33 F3 dw $F333 KERNAL CLRCHN routine vector 0324 FB 03 dw $03FB KERNAL CHRIN routine vector 0326 FB 03 dw $03FB KERNAL CHROUT routine vector 0328 B1 F1 dw $F1B1 KERNAL STOP routine vector 032A FB 03 dw $03FB KERNAL GETIN routine vector 032C 5E
033C 03 dw 03 Header type
033D BA 02 dw 02BA Starting address
033F 2C 03 dw 032C Ending address
0341 20 20 20 20 20 20 20 20 Name of Game
0349 20 20 20 20 20 20 20 20
0351 47 41 4C 41 44 52 49 45 GALADRIEL SW. C.
0359 4C 20 53 57 2E 20 43 2E
Routine: Read the program
0361 AD 11 D0 LDA $D011 VIC control register
0364 29 EF AND #$EF Fill the screen with border color
0366 8D 11 D0 STA $D011 VIC control register
0369 A0 00 LDY #$00
036B 84 C0 STY $C0 Stop motor of tape
036D CA DEX
036E D0 FD BNE $036D Tape I/O buffer
0370 88 DEY
0371 D0 FA BNE $036D Tape I/O buffer
0373 78 SEI
0374 84 D7 STY $D7 Last key/checksum/buffer
0376 A9 07 LDA #$07 Count 107h=263 cycle of ~1Mhz
0378 8D 06 DD STA $DD06 Timer B #2: Lo Byte
037B A2 01 LDX #$01
037D 20 E5 03 JSR $03E5 Routine: Read a bit in Carry
0380 26 BD ROL $BD RS-232 output parity/Transient cassette
0382 A5 BD LDA $BD RS-232 output parity/Transient cassette
0384 C9 02 CMP #$02 Synchronization byte
0386 D0 F5 BNE $037D Tape I/O buffer
0388 A0 10 LDY #$10 Countdown start of sequence
038A 20 D2 03 JSR $03D2 Routine: Read a byte in A and $BD
038D C9 02 CMP #$02 Synchronization byte
038F F0 F9 BEQ $038A Tape I/O buffer
0391 C4 BD CPY $BD RS-232 output parity/Transient cassette
0393 D0 E8 BNE $037D Tape I/O buffer
0395 20 D2 03 JSR $03D2 Routine: Read a byte in A and $BD
0398 88 DEY Execute countdown
0399 D0 F6 BNE $0391 Tape I/O buffer
039B 20 D2 03 JSR $03D2 Routine: Read a byte in A and $BD
039E 91 26 STA ($26),Y Store the readed byte to its position
03A0 D1 26 CMP ($26),Y Real product
03A2 F0 02 BEQ $03A6 Tape I/O buffer
03A4 86 90 STX $90 Statusbyte ST of I/O KERNAL
03A6 45 D7 EOR $D7 Last key/checksum/buffer
03A8 85 D7 STA $D7 Last key/checksum/buffer
03AA E6 26 INC $26 Real product
03AC D0 02 BNE $03B0 Tape I/O buffer
03AE E6 27 INC $27 Real product
03B0 A5 26 LDA $26 Real product
03B2 C5 62 CMP $62 Floating point accumulator #1: Mantissa
03B4 A5 27 LDA $27 Real product
03B6 E5 63 SBC $63 Floating point accumulator #1: Mantissa
03B8 90 E1 BCC $039B Tape I/O buffer
03BA 20 D2 03 JSR $03D2 Routine: Read a byte in A and $BD
03BD A0 00 LDY #$00 The readed byte is the checksum
03BF CA DEX
03C0 D0 FD BNE $03BF Tape I/O buffer
03C2 88 DEY
03C3 D0 FA BNE $03BF Tape I/O buffer
03C5 C8 INY
03C6 84 C0 STY $C0 Stop motor of tape
03C8 58 CLI
03C9 18 CLC
03CA A9 00 LDA #$00
03CC 8D A0 02 STA $02A0 Contain IRQ vector during tape I/O
03CF 4C 93 FC JMP $FC93 Routine: Stop motor, disable int.CIA #1
Routine: Read a byte in A and $BD
03D2 A9 08 LDA #$08
03D4 85 A3 STA $A3 Serial counter of bits: Flag EOI
03D6 20 E5 03 JSR $03E5 Routine: Read a bit in Carry
03D9 26 BD ROL $BD RS-232 output parity/Transient cassette
03DB EA NOP The first bit is the hi
03DC EA NOP
03DD EA NOP
03DE C6 A3 DEC $A3 Serial counter of bits: Flag EOI
03E0 D0 F4 BNE $03D6 Tape I/O buffer
03E2 A5 BD LDA $BD RS-232 output parity/Transient cassette
03E4 60 RTS
Routine: Read a bit in Carry
03E5 A9 10 LDA #$10
03E7 2C 0D DC BIT $DC0D Interrupt control register CIA #1
03EA F0 FB BEQ $03E7 Jump if read tape value is hi
03EC AD 0D DD LDA $DD0D Interrupt control register CIA #2
03EF 8E 07 DD STX $DD07 Timer B #2: HI Byte
03F2 48 PHA
03F3 A9 19 LDA #$19 Count 107h=263 cycle of ~1Mhz
03F5 8D 0F DD STA $DD0F Control register B of CIA #2
03F8 68 PLA Timer B #2 interrupt value is the bit
03F9 4A LSR A if 0, the timer countdown is not ended
03FA 4A LSR A if 1, the countdown of timer is ended
03FB 60 RTS
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commodore 64 | 
Tognon Stefano programs
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