support Disk Recovery (#37)

* support Disk Recovery

* enable booting Disk Recovery from drive 2

src/anti-m.a

@@ -6,7 +6,7 @@
 ;-------------------------------
 ; Anti-M
 ; a 4am hack
-; (c) 2019-2020 by 4am
+; (c) 2019-2022 by 4am
 ;
 ; Permission is hereby granted, free of charge, to any
 ; person obtaining a copy of this software and associated
@@ -157,7 +157,7 @@ CheckDrive2
          lda   $C0EB
          jsr   @spinup
          jsr   @seek
-         ldx   #2
+         ldx   #21
          ldy   #0
 ---      iny
          bne   +
@@ -240,9 +240,9 @@ tmpsec=$3c
 --       ldx     #$11
 -        dex
          bne     -
-         inc     tmpsec
+         inc     $46
          bne     +
-         inc     tmpsec+1
+         inc     $47
 +        sec
          sbc     #1
          bne     --
@@ -346,7 +346,7 @@ StringTable
          !word @mainmenu
 
 @header
-         !text "Anti-M v1.8pre by 4am         2020-12-27"
+         !text "Anti-M v1.9pre by 4am         2022-03-20"
          !text "________________________________________",$8D
          !text $8D,$8D,$8D,$8D,$8D,$8D,$8D,$8D,$00
 @mainmenu

src/idbroderbund.a

@@ -24,6 +24,7 @@
 ; - Phaser Fire (Gebelli)
 ; - Russki Duck (Gebelli)
 ; - Zenith (Gebelli)
+; - Disk Recovery (Sensible Software)
 ;
 IDBroderbund
 ; first stage is just a standard hybrid DOS 3.2/3.3 bootloader
@@ -269,6 +270,8 @@ IDBroderbund
          bne   @jmpdos
 
 @hookhybrid
+         lda   #$0C
+         sta   $300 ;Sensible Software page-wraparound fix
          lda   #$4C
          sta   $33C
          stx   $33D
@@ -315,6 +318,16 @@ IDBroderbund
          beq   @skip2a
          inc   $3D60
 @skip2a
++        ldy   $371D
+         cpy   $371F   
+         bne   +
+         dey
+         bne   +
+         lda   $371E
+         ora   $3720
+         ora   $3721
+         bne   +
+         inc   $371F                 ; select drive 2
 +        jmp   $3700                 ; let it goooo...
 
 @SpaceEggsCallback3 !pseudopc $300 {