Loader: Elite GMA loader (Part 4 of 4)

       Name: Elite GMA loader (Part 4 of 4)                          [Show more]
       Type: Subroutine
   Category: Loader
    Summary: Load the GMA5 and GMA6 binaries and start the game
    Context: See this subroutine in context in the source code
 References: No direct references to this subroutine in this source file


.load4

                        ; When the Elite loader has finished, it jumps back here
                        ; via the instruction we inserted into address $CE0E

 CLC                    ; Call CopyZeroPage with the C flag clear to copy the
 JSR CopyZeroPage       ; contents of zero page to $CE00, so we can restore it
                        ; once we have finished loading the game binaries

 LDA L1                 ; Set bits 0 to 2 of the 6510 port register at location
 AND #%11111000         ; L1 to %110 to set the input/output port to the
 ORA #%00101110         ; following:
 STA L1                 ;
                        ;   * LORAM = 0
                        ;   * HIRAM = 1
                        ;   * CHAREN = 1
                        ;
                        ; This sets the entire 64K memory map to RAM except for
                        ; the I/O memory map at $D000-$DFFF, which gets mapped
                        ; to registers in the VIC-II video controller chip, the
                        ; SID sound chip, the two CIA I/O chips, and so on, and
                        ; $E000-$FFFF, which gets mapped to the Kernal ROM
                        ;
                        ; See the memory map at the bottom of page 264 in the
                        ; Programmer's Reference Guide
                        ;
                        ; This also sets bits 3 and 5 to configure the Datasette
                        ; as follows:
                        ;
                        ;   * Bit 3 = Datasette output signal level 1
                        ;
                        ;   * Bit 5 = Datasette motor control off

IF _GMA86_PAL

 LDA #5                 ; Call LoadGMAFile to load the GMA5 file, which contains
 JSR LoadGMAFile        ; the first block of game code (ELITE A to C)

 LDA #6                 ; Call LoadGMAFile to load the GMA6 file, which contains
 JSR LoadGMAFile        ; the second block of game code (ELITE D onwards)

ELIF _GMA85_NTSC

 LDA #'5'               ; Call LoadGMAFile to load the GMA5 file, which contains
 JSR LoadGMAFile        ; the first block of game code (ELITE A to C)

 LDA #'6'               ; Call LoadGMAFile to load the GMA6 file, which contains
 JSR LoadGMAFile        ; the second block of game code (ELITE D onwards)

ENDIF

 LDA L1                 ; Set bits 0 to 2 of the 6510 port register at location
 AND #%11111000         ; L1 to %110 to set the input/output port to the
 ORA #%00000110         ; following:
 STA L1                 ;
                        ;   * LORAM = 0
                        ;   * HIRAM = 1
                        ;   * CHAREN = 1
                        ;
                        ; This sets the entire 64K memory map to RAM except for
                        ; the I/O memory map at $D000-$DFFF, which gets mapped
                        ; to registers in the VIC-II video controller chip, the
                        ; SID sound chip, the two CIA I/O chips, and so on, and
                        ; $E000-$FFFF, which gets mapped to the Kernal ROM
                        ;
                        ; See the memory map at the bottom of page 264 in the
                        ; Programmer's Reference Guide

 SEC                    ; Call CopyZeroPage with the C flag set to restore the
 JSR CopyZeroPage       ; contents of zero page from $CE00, which we backed up
                        ; above

 JSR KERNALRESTOR       ; Call the Kernal's RESTOR function to restore the
                        ; vector table at $0314 to $0333 with the default
                        ; values, so the fast loader code is no longer called
                        ; when we use the Kernal's file functions

 JSR KERNALCLALL        ; Call the Kernal's CLALL function to clear the file
                        ; table and close any open files

 JMP S%                 ; Jump to S% in the GMA5 game binary we just loaded, to
                        ; finally start the game