Routines
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34762: Display the title screen and play the theme tune
Used by the routines at 34463, 35245 and 35914.
The first thing this routine does is initialise some game status buffer variables in preparation for the next game.
34762 XOR A A=0
34763 LD (34254),A Initialise the Kempston joystick indicator at 34254
34766 LD (34273),A Initialise the in-game music note index at 34273
34769 LD (34253),A Initialise the (unused) screen flash counter at 34253
34772 LD (34257),A Initialise the airborne status indicator at 34257
34775 LD (34251),A Initialise the minute counter at 34251
34778 LD (34272),A Initialise the inactivity timer at 34272
34781 LD (34271),A Initialise the game mode indicator at 34271
34784 LD A,7 Initialise the number of lives remaining at 34252
34786 LD (34252),A
34789 LD A,208 Initialise Willy's y-coordinate at 34255
34791 LD (34255),A
34794 LD A,33 Initialise the current room number at 33824 to 33 (The Bathroom)
34796 LD (33824),A
34799 LD HL,23988 Initialise Willy's coordinates at 34259 to (13,20)
34802 LD (34259),HL
34805 LD HL,34172 Initialise the number of items collected at 34172 to "000"
34808 LD (HL),48
34810 INC HL
34811 LD (HL),48
34813 INC HL
34814 LD (HL),48
34816 LD H,164 Page 164 holds the first byte of each entry in the item table
34818 LD A,(41983) Pick up the index of the first item from 41983
34821 LD L,A Point HL at the entry for the first item
34822 LD (34270),A Initialise the counter of items remaining at 34270
34825 SET 6,(HL) Set the collection flag for every item in the item table at 41984
34827 INC L
34828 JR NZ,34825
34830 LD HL,34274 Initialise the keypress flag in bit 0 at 34274
34833 SET 0,(HL)
Next, prepare the screen.
34835 LD HL,16384 Clear the entire display file
34838 LD DE,16385
34841 LD BC,6143
34844 LD (HL),0
34846 LDIR
34848 LD HL,38912 Copy the attribute bytes for the title screen from 38912 and 39424 to the attribute file
34851 LD BC,768
34854 LDIR
34856 LD HL,23136 Copy the attribute value 70 (INK 6: PAPER 0: BRIGHT 1) into the row of 32 cells from (19,0) to (19,31) on the screen
34859 LD DE,23137
34862 LD BC,31
34865 LD (HL),70
34867 LDIR
34869 LD IX,33876 Print "+++++ Press ENTER to Start +++++" (see 33876) at (19,0)
34873 LD DE,20576
34876 LD C,32
34878 CALL 38528
34881 LD DE,22528 Point DE at the first byte of the attribute file
The following loop scans the top two-thirds of the attribute file, which contains values 0, 4, 5, 8, 9, 36, 37, 40, 41, 44, 45 and 211 (copied from 38912). Whenever a value other than 0, 9, 36, 45 or 211 is found, a triangle UDG is drawn at the corresponding location in the display file.
34884 LD A,(DE) Pick up a byte from the attribute file
34885 OR A Is it 0 (INK 0: PAPER 0)?
34886 JR Z,34958 If so, jump to consider the next byte in the attribute file
34888 CP 211 Is it 211 (INK 3: PAPER 2: BRIGHT 1: FLASH 1)?
34890 JR Z,34958 If so, jump to consider the next byte in the attribute file
34892 CP 9 Is it 9 (INK 1: PAPER 1)?
34894 JR Z,34958 If so, jump to consider the next byte in the attribute file
34896 CP 45 Is it 45 (INK 5: PAPER 5)?
34898 JR Z,34958 If so, jump to consider the next byte in the attribute file
34900 CP 36 Is it 36 (INK 4: PAPER 4)?
34902 JR Z,34958 If so, jump to consider the next byte in the attribute file
34904 LD C,0 C=0; this will be used as an offset from the triangle UDG base address (33841)
34906 CP 8 Is the attribute value 8 (INK 0: PAPER 1)?
34908 JR Z,34929 Jump if so
34910 CP 41 Is it 41 (INK 1: PAPER 5)?
34912 JR Z,34929 Jump if so
34914 CP 44 Is it 44 (INK 4: PAPER 5)?
34916 JR Z,34926 Jump if so
34918 CP 5 Is it 5 (INK 5: PAPER 0)?
34920 JR Z,34929 Jump if so
34922 LD C,16 Set the triangle UDG offset to 16
34924 JR 34929
34926 LD A,37 Change the attribute byte here from 44 (INK 4: PAPER 5) to 37 (INK 5: PAPER 4)
34928 LD (DE),A
34929 LD A,E Point HL at the triangle UDG to draw (33841, 33849, 33857 or 33865)
34930 AND 1
34932 RLCA
34933 RLCA
34934 RLCA
34935 OR C
34936 LD C,A
34937 LD B,0
34939 LD HL,33841
34942 ADD HL,BC
34943 PUSH DE Save the attribute file address briefly
34944 BIT 0,D Set the zero flag if we're still in the top third of the attribute file
34946 LD D,64 Point DE at the top third of the display file
34948 JR Z,34952 Jump if we're still in the top third of the attribute file
34950 LD D,72 Point DE at the middle third of the display file
34952 LD B,8 There are eight pixel rows in a triangle UDG
34954 CALL 38555 Draw a triangle UDG on the screen
34957 POP DE Restore the attribute file address to DE
34958 INC DE Point DE at the next byte in the attribute file
34959 LD A,D Have we finished scanning the top two-thirds of the attribute file yet?
34960 CP 90
34962 JP NZ,34884 If not, jump back to examine the next byte
Now check whether there is a joystick connected.
34965 LD BC,31 This is the joystick port
34968 DI Disable interrupts (which are already disabled)
34969 XOR A A=0
34970 IN E,(C) Combine 256 readings of the joystick port in A; if no joystick is connected, some of these readings will have bit 5 set
34972 OR E
34973 DJNZ 34970
34975 AND 32 Is a joystick connected (bit 5 reset)?
34977 JR NZ,34984 Jump if not
34979 LD A,1 Set the Kempston joystick indicator at 34254 to 1
34981 LD (34254),A
And finally, play the theme tune and check for keypresses.
34984 LD HL,34299 Point HL at the theme tune data at 34299
34987 CALL 38562 Play the theme tune
34990 JP NZ,35068 Start the game if ENTER, 0 or the fire button was pressed
No key was pressed while the theme tune was playing, so scroll a message across the screen while repeatedly producing a screeching sound effect.
34993 XOR A Initialise the temporary game status buffer variable at 34276 to 0; this will be used as an index for the message scrolled across the screen (see 33876)
34994 LD (34276),A
34997 CALL 35563 Cycle the INK and PAPER colours
35000 LD HL,23136 Copy the attribute value 79 (INK 7: PAPER 1: BRIGHT 1) into the row of 32 cells from (19,0) to (19,31) on the screen
35003 LD DE,23137
35006 LD BC,31
35009 LD (HL),79
35011 LDIR
35013 LD A,(34276) Pick up the message index from 34276
35016 LD IX,33876 Point IX at the corresponding location in the message at 33876
35020 LD E,A
35021 LD D,0
35023 ADD IX,DE
35025 LD DE,20576 Print 32 characters of the message at (19,0)
35028 LD C,32
35030 CALL 38528
35033 LD A,(34276) Prepare a value between 50 and 81 in A (for the routine at 38622)
35036 AND 31
35038 ADD A,50
35040 CALL 38622 Make a sound effect
35043 LD BC,45054 Read keys H-J-K-L-ENTER and 6-7-8-9-0
35046 IN A,(C)
35048 AND 1 Keep only bit 0 of the result (ENTER, 0)
35050 CP 1 Was ENTER or 0 pressed?
35052 JR NZ,35068 Jump if so to start the game
35054 LD A,(34276) Pick up the message index from 34276
35057 INC A Increment it
35058 CP 224 Set the zero flag if we've reached the end of the message
35060 LD (34276),A Store the new message index at 34276
35063 JR NZ,34997 Jump back unless we've finished scrolling the message across the screen
35065 JP 34835 Jump back to prepare the screen and play the theme tune again
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