Properly test for Alternate Display Mode on //gs (#529)

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src/constants.a

@@ -108,6 +108,7 @@ ROM_TEXT =     $FB2F
 ROM_MACHINEID =$FBB3
 ROM_MACHINE2C =$FBC0
 ROM_HOME =     $FC58
+ROM_WAIT =     $FCA8
 ROM_COUT =     $FDED
 ROM_NORMAL =   $FE84      ; NORMAL text (instead of INVERSE or FLASH)
 ROM_IN0 =      $FE89      ; SETKBD

src/demo/gamma.goblins.a

@@ -9,7 +9,7 @@
          !source "src/macros.a"
 
          +GAME_REQUIRES_JOYSTICK
-         +USES_TEXT_PAGE_2
+         +TEST_TEXT_PAGE_2
          +ENABLE_ACCEL_LC
          +LOAD_XSINGLE title
 

src/demo/pacman.a

@@ -11,13 +11,14 @@
          +ENABLE_ACCEL_LC
          +LOAD_XSINGLE title
 
-         +USES_TEXT_PAGE_2
          +NEW_RESET_VECTOR $280
 
          lda   #$60
          sta   $813
          jsr   $800       ; decompress
 
+         +TEST_TEXT_PAGE_2
+
          lda   #$80
          sta   $103F
          lda   #2

src/demo/stellar.7.a

@@ -8,7 +8,6 @@
          !source "src/constants.a"   ; no code in these
          !source "src/macros.a"
 
-         +USES_TEXT_PAGE_2
          +READ_RAM2_WRITE_RAM2
          jsr   EnableAccelerator
          +LOAD_FILE_KEEP_DIR stellar_7, stellar_7_dir_e-stellar_7_dir_b
@@ -17,6 +16,8 @@
          sta   $863
          jsr   $800       ; unpack
 
+         +TEST_TEXT_PAGE_2
+
          ldx   #0
          stx   $AE2A
          inx

src/demo/the.goonies.a

@@ -8,7 +8,7 @@
          !source "src/constants.a"   ; no code in these
          !source "src/macros.a"
 
-         +USES_TEXT_PAGE_2
+         +TEST_TEXT_PAGE_2
          +READ_RAM2_WRITE_RAM2
          jsr   EnableAccelerator
          +LOAD_FILE_KEEP_DIR the_goonies, the_goonies_dir_e-the_goonies_dir_b
@@ -16,7 +16,7 @@
          sta   $1045
          jsr   $1000      ; decompress
          ldx   #$2C
-         stx   $6BF
+         stx   $6BF       ; skip text screen
          ldx   #$60
          stx   $60C
          stx   $622
@@ -28,9 +28,9 @@
          ldx   #0
          stx   $4070
          inx
-         stx   $4071
+         stx   $4071      ; set exit
          lda   #$2C
-         sta   $4039
+         sta   $4039      ; don't play music
          +DISABLE_ACCEL
          jsr   $4000      ; title
          jsr   $60F       ; load level

src/macros.a

@@ -364,6 +364,27 @@
 +
 }
 
+!macro   TEST_TEXT_PAGE_2 {
+         lda   ROM_MACHINEID
+         cmp   #$06
+         bne   ++
+         sec
+         jsr   $FE1F                 ; check for IIgs
+         bcs   ++
+         lda   #$20                  ; check if Alternate Display Mode is already on
+         sta   $0800
+         lda   #$FF
+         jsr   ROM_WAIT
+!cpu 65816
+         lda   $E00800               ; did we shadow copy data to shadow bank $E0?
+         cmp   #$20
+         beq   +
+!cpu 6502              ; https://archive.org/details/develop-04_9010_October_1990/page/n51/mode/1up
+         jsr   ROM_TEXT2COPY         ; set alternate display mode on IIgs (required for some games)
++        cli                         ; enable VBL interrupts
+++
+}
+
 !macro   RESET_VECTOR .addr {
          lda   #<.addr
          sta   $3F2

src/proboothd/proboothd.a

@@ -35,7 +35,7 @@
          sta   $c002
          sta   $c004
          lda   $c000
-         cmp   #$d3
+         cmp   #$d3    ; Press "S" on bootup
          bne   +
          jsr   seasons
 +        jsr   $fb2f