support Sensible Speller (#30)

src/anti-m.a

@@ -207,10 +207,13 @@ Tracer13
          bcc   BeginTheBoot13
          jsr   IDBoot13
          bcc   BeginTheBoot13
+         jsr   IDSensible
+         bcc   BeginTheBoot13
 ; [execution falls through here]
 ; [and runs anyway]
 
 BeginTheBoot13
+         ldx   #$B3 ;Sensible Software fix
          ldy   $0300
          jmp   $0301
 
@@ -255,7 +258,7 @@ StringTable
          !word @mainmenu
 
 @header
-         !text "Anti-M v1.7 by 4am            2020-08-11"
+         !text "Anti-M v1.8pre by 4am         2020-10-15"
          !text "________________________________________",$8D
          !text $8D,$8D,$8D,$8D,$8D,$8D,$8D,$8D,$00
 @mainmenu
@@ -273,3 +276,4 @@ StringTable
          !src  "src/idprogame.a"
          !src  "src/idpersonal.a"
          !src  "src/idalphabeta.a"
+         !src  "src/idsensible.a"

src/idboot.a

@@ -10,6 +10,11 @@ IDBoot
          ldy   #$5C
          sty   @patch+1
          bcc   +
+
+; we found D5 AA 96 T00S00 D5 AA ..
+; check for weird Sensible Software 13-sector disk with D5 AA 96 sectors
+         cmp   #$B5
+         beq   ++
          lda   #$90
          sta   $867B
 
@@ -29,7 +34,7 @@ IDBoot
          bne   @patch
 
 ; and loop anyway in case it's a hybrid disk and we missed the D5 AA 96
-         dec   @retries
+++       dec   @retries
          bne   @patch
 
 ; found nothing but D5 AA B5, proceed as 13-sector

src/idsensible.a

@@ -0,0 +1,42 @@
+; Sensible Software tracer
+; written by qkumba
+;
+; tested on
+; - Sensible Speller
+;
+IDSensible
+         lda   #3
+         ldx   #1
+         ldy   #6
+         jsr   CompareMemory
+         !byte $29,$00 ;AND #$00
+         !byte $85,$3A ;STA $3A
+         !byte $9A     ;TXS
+         !byte $08     ;PHP
+         bcs   @exit
+
+; patch encoded code to regain control after it loads sectors into $400+
+         lda   #(<@pcallback) xor $99
+         sta   $03A3
+         lda   #(>@pcallback) xor $99
+         sta   $03A4
+
+@exit
+         rts
+
+@pcallback
+         !word @callback
+
+@callback
+
+; disable ROM checksum-failure branching
+         lda   $6CE
+         cmp   #$4C
+         bne   +
+         lda   #$60
+         sta   $6CE
+
+; and nibble check which fails occasionally
+         lda   #$2C
+         sta   $79B
++        jmp   ($0026)