.TITLE STY distaway ; Store the ship distance in distaway PHA ; Store the token number on the stack for later STX TYPE ; Store the ship type in location TYPE LDA #$FF ; Set MULIE to $FF to prevent the RESET routine from STA MULIE ; stopping the title music that is currently playing JSR RESET ; Reset our ship so we can use it for the rotating ; title ship LDA #0 ; Set MULIE back to 0 so the RESET routine goes back to STA MULIE ; its normal behaviour of stopping any music that is ; playing JSR ZEKTRAN ; Call ZEKTRAN to clear the key logger ;LDA #32 ; These instructions are commented out in the original ;JSR DOVDU19 ; source LDA #13 ; Clear the top part of the screen, draw a border box, JSR TT66 ; and set the current view type in QQ11 to 13 (rotating ; ship view) ;LDA #RED ; These instructions are commented out in the original ;JSR DOCOL ; source LDA #0 ; Set QQ11 to 0, so from here on we are using a space STA QQ11 ; view LDA #96 ; Set nosev_z hi = 96 (96 is the value of unity in the STA INWK+14 ; rotation vector) LDA #96 ; Set A = 96 as the distance that the ship starts at STA INWK+7 ; Set z_hi, the high byte of the ship's z-coordinate, ; to 96, which is the distance at which the rotating ; ship starts out before coming towards us LDX #127 ; Set roll counter = 127, so don't dampen the roll and STX INWK+29 ; make the roll direction clockwise STX INWK+30 ; Set pitch counter = 127, so don't dampen the pitch and ; set the pitch direction to dive INX ; Set QQ17 to 128 (so bit 7 is set) to switch to STX QQ17 ; Sentence Case, with the next letter printing in upper ; case LDA TYPE ; Set up a new ship, using the ship type in TYPE JSR NWSHP LDA #6 ; Move the text cursor to column 6 STA XC LDA #30 ; Print recursive token 144 ("---- E L I T E ----") JSR plf ; followed by a newline LDA #10 ; Print a line feed to move the text cursor down a line JSR TT26 LDA #6 ; Move the text cursor to column 6 again STA XC LDA PATG ; If PATG = 0, skip the following two lines, which BEQ awe ; print the author credits (PATG can be toggled by ; pausing the game and pressing "X") LDA #13 ; Print extended token 13 ("BY D.BRABEN & I.BELL") JSR DETOK .awe LDA brkd ; If brkd = 0, jump to BRBR2 to skip the following, as BEQ BRBR2 ; we do not have a system error message to display ; If we get here then brkd = $FF, which indicates that ; we have a system error we need to display INC brkd ; Set brkd = 0 to clear the error flag and indicate that ; the error has been processed LDA #7 ; Move the text cursor to column 7 STA XC LDA #9 ; Move the text cursor to row 9 STA YC ; The following loop prints out the null-terminated ; message pointed to by ($FD $FE), which is the OS ; error message pointer - so this prints the error ; message on the next line LDY #0 ; Set Y = 0 to act as a character counter JSR CHPR ; Print the character in A (which contains a line feed ; on the first loop iteration), and then any non-zero ; characters we fetch from the error message INY ; Increment the loop counter LDA ($FD),Y ; Fetch the Y-th byte of the block pointed to by ; ($FD $FE), so that's the Y-th character of the message ; pointed to by the OS error message pointer BNE P%-6 ; If the fetched character is non-zero, loop back to the ; JSR CHPR above to print it, and keep looping until ; we fetch a zero (which marks the end of the message) .BRBR2 LDY #0 ; Set DELTA = 0 (i.e. ship speed = 0) STY DELTA STY JSTK ; Set JSTK = 0 (i.e. keyboard, not joystick) LDA #14 ; Move the text cursor to row 14 STA YC LDA #1 ; Move the text cursor to column 1 STA XC PLA ; Restore the recursive token number we stored on the ; stack at the start of this subroutine JSR DETOK ; Print the extended token in A LDA #3 ; Move the text cursor to column 3 STA XC LDA #12 ; Print extended token 12 ("{single cap}C) {single JSR DETOK ; cap}D.{single cap}BRABEN & {single cap}I.{single ; cap}BELL 1985") LDA #12 ; Set CNT2 = 12 as the outer loop counter for the loop STA CNT2 ; starting at TLL2 LDA #5 ; Set the main loop counter in MCNT to 5, to act as the STA MCNT ; inner loop counter for the loop starting at TLL2 .TLL2 LDA INWK+7 ; If z_hi (the ship's distance) is 1, jump to TL1 to CMP #1 ; skip the following decrement BEQ TL1 DEC INWK+7 ; Decrement the ship's distance, to bring the ship ; a bit closer to us .TL1 JSR MVEIT ; Move the ship in space according to the orientation ; vectors and the new value in z_hi LDX distaway ; Set z_lo to the distance value we passed to the STX INWK+6 ; routine, so this is the closest the ship gets to us LDA MCNT ; This has no effect - it is presumably left over from AND #3 ; the other versions of Elite which only scan the ; keyboard once every four loops, but that isn't the ; case here as the result is not acted upon LDA #0 ; Set x_lo = 0, so the ship remains in the screen centre STA INWK STA INWK+3 ; Set y_lo = 0, so the ship remains in the screen centre JSR LL9 ; Call LL9 to display the ship JSR RDKEY ; Scan the keyboard for a key press and return the ASCII ; code of the key pressed in A and X (or 0 for no key ; press) ; ; This also clears the C flag if no keys are being ; pressed DEC MCNT ; Decrement the main loop counter LDA $C061 ; Combine the soft switches at PB0 and PB1, which are ORA $C062 ; mapped to push button 0 and 1 (i.e. the fire buttons ; on the joysticks) ; ; If a fire button is being pressed then bit 7 in that ; soft switch will be set, so this sets bit 7 of A if ; either one of the fire buttons is being pressed IF _IB_DISK OR _4AM_CRACK AND fireButtonMask ; This is a strange bit of code - fireButtonMask is set ; to %00001011 but it is never changed, so this AND will ; always clear bit 7 ; ; This means that we will never take the following ; branch to TL3, so we will never be able to configure ; the joystick from the title screen by pressing fire ; ; The value of %00001011 in fireButtonMask is also a bit ; odd, as $C061 and $C062 only record the button status ; in bit 7, so the mask value is rather intriguing too ENDIF BMI TL3 ; If bit 7 of A is set then the fire button is being ; pressed, so jump to TL3 to set the JSTK configuration ; option to enable joysticks BCC TLL2 ; If no key is being pressed then the C flag will be ; clear from the call to RDKEY, so loop back up to ; move/rotate the ship and check again for a key press RTS ; Return from the subroutine .TL3 DEC JSTK ; Joystick fire button was pressed, so set JSTK to $FF ; (it was set to 0 above), to disable keyboard and ; enable joysticks RTS ; Return from the subroutineName: TITLE [Show more] Type: Subroutine Category: Start and end Summary: Display a title screen with a rotating ship and promptContext: See this subroutine in context in the source code References: This subroutine is called as follows: * BR1 (Part 1 of 2) calls TITLE * BR1 (Part 2 of 2) calls TITLE
Display the title screen, with a rotating ship and a text token at the bottom of the screen.
Arguments: A The number of the extended token to show below the rotating ship (see variable TKN1 for details of recursive tokens) X The type of the ship to show (see variable XX21 for a list of ship types) Y The distance to show the ship rotating, once it has finished moving towards us
Returns: X If a key is being pressed, X contains the ASCII code of the key pressed
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Label BRBR2 is local to this routine
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Subroutine CHPR (category: Text)
Print a character at the text cursor by poking into screen memory
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Subroutine DETOK (category: Text)
Print an extended recursive token from the TKN1 token table
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Variable JSTK in workspace Option variables
Keyboard or joystick configuration setting
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Subroutine LL9 (Part 1 of 12) (category: Drawing ships)
Draw ship: Check if ship is exploding, check if ship is in front
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Variable MULIE in workspace Option variables
A flag to record whether the RESET routine is being being called from within the TITLE routine, when the title screen is being displayed, as we don't want to stop the title music from playing when this is the case
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Subroutine MVEIT (Part 1 of 9) (category: Moving)
Move current ship: Tidy the orientation vectors
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Subroutine NWSHP (category: Universe)
Add a new ship to our local bubble of universe
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Variable PATG in workspace Option variables
Configuration setting to show the author names on the start-up screen and enable manual hyperspace mis-jumps
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Subroutine RDKEY (category: Keyboard)
Scan the keyboard for key presses and the joystick, and update the key logger
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Subroutine RESET (category: Start and end)
Reset most variables
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Label TL1 is local to this routine
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Label TL3 is local to this routine
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Label TLL2 is local to this routine
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Subroutine TT26 (category: Text)
Print a character at the text cursor, with support for verified text in extended tokens
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Subroutine TT66 (category: Drawing the screen)
Clear the screen and set the current view type
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Subroutine ZEKTRAN (category: Keyboard)
Clear the key logger
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Label awe is local to this routine
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Variable brkd (category: Utility routines)
A flag that indicates whether a system error has occurred
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Variable fireButtonMask in workspace Option variables
This value is applied to the joystick fire button soft switches in the TITLE routine, where it disables the ability to configure joysticks by pressing a fire button
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Subroutine plf (category: Text)
Print a text token followed by a newline