The PAS1 subroutine - Elite on the 6502

       Name: PAS1                                                    [Show more]
       Type: Subroutine
   Category: Missions
    Summary: Display a rotating ship at space coordinates (0, conhieght, 256)
             and scan the keyboard
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * PAUSE calls PAS1


 Returns:

   X                    If a key is being pressed, X contains the ASCII code of
                        the key being pressed, otherwise it contains 0

   A                    Contains the same as X


.PAS1

 LDA #conhieght         ; Set y_lo = conhieght
 STA INWK+3

 LDA #0                 ; Set x_lo = 0
 STA INWK

 STA INWK+6             ; Set z_lo = 0

 LDA #2                 ; Set z_hi = 1, so (z_hi z_lo) = 256
 STA INWK+7

 JSR LL9                ; Draw the ship on screen

 JSR MVEIT              ; Call MVEIT to move and rotate the ship in space

 JMP RDKEY              ; Scan the keyboard for a key press and return the
                        ; ASCII code of the key pressed in X (or 0 for no key
                        ; press), returning from the subroutine using a tail
                        ; call

[X]

Variable INWK in workspace ZP

The zero-page internal workspace for the current ship data block

[X]

Subroutine LL9 (Part 1 of 12) (category: Drawing ships)

Draw ship: Check if ship is exploding, check if ship is in front

[X]

Subroutine MVEIT (Part 1 of 9) (category: Moving)

Move current ship: Tidy the orientation vectors

[X]

Subroutine RDKEY (category: Keyboard)

Scan the keyboard for key presses

[X]

Configuration variable conhieght = 80

The size of the gap left for the rotating Constrictor at the top of the briefing for mission 1

Missions: PAS1

[Commodore 64 version]