skip playing Pollywog demo on ROM0 or ROM1 IIgs (#625)

Better fix; just don't play the Pollywog demo on a ROM0 or ROM1 that can't properly display page 2. We can't turn on Alternate Display Mode due to its use of VBL interrupts on these machines. We can detect and turn it on with ROM3, however, where it does not use interrupts.

src/demo/pollywog.a

@@ -9,9 +9,35 @@
          !source "src/macros.a"
 
          +GAME_REQUIRES_JOYSTICK
-         +TEST_TEXT_PAGE_2           ; will look wonky on ROM0/1 Apple //gs
-                                     ; due to lores page flipping
-         +ENABLE_ACCEL_LC
+         
+         lda   ROM_MACHINEID         ; is already on. ROM0 and ROM1 versions of ADM use
+         cmp   #$06                  ; interrupts and can cause hangs, so safer to just
+         bne   ++                    ; leave it turned off, especially in ATTRACT/DEMO mode.
+         sec
+         jsr   $FE1F                 ; check for IIgs
+         bcs   +++
+         tya                         ; GS ID routine returns with ROM version in Y
+         cmp   #0                    ; ROM 0?
+         beq   ++
+         cmp   #1                    ; ROM 1?
+         beq   ++
+         lda   #$20
+         sta   $0800                 ; check if Alternate Display Mode is already on
+         lda   #$FF
+         jsr   ROM_WAIT              ; skip a VBL cycle
+!cpu 65816
+         lda   $E00800               ; did we shadow copy data to bank $E0?
+         cmp   #$20
+         beq   +                     ; only call TEXT2COPY if we know it's off
+!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
+         jmp   +++
+
+++       jmp   $100       ; can't play demo on ROM0 or ROM1 Apple IIgs
+                          ; due to extensive use of page 2 throughout
+
++++      +ENABLE_ACCEL_LC
          +LOAD_XSINGLE title
          +READ_ROM_NO_WRITE