From 39758aaba97ec00e297c5e57e58ed33fbf718342 Mon Sep 17 00:00:00 2001
From: 4am <a2_4am@sent.com>
Date: Mon, 26 Jun 2023 20:39:38 -0400
Subject: [PATCH] add unexpected 5&3 track detection [fixes Real Math]

---
 README.md          |  2 ++
 src/strings/en.a   |  6 ++++-
 src/strings/enid.a |  1 +
 src/wholetrack.a   | 56 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 82375ed..3b814b3 100644
--- a/README.md
+++ b/README.md
@@ -473,6 +473,8 @@ development branch
 - NEW: patchers/t00_scottforesman_
   dos33.a (fixes Addition and
   Subtraction 3, Decimals 2)
+- NEW: unexpected 5&3 track detection
+  (fixes Real Math, Mathosaurus)
 - IMPROVED: patchers/d5d5f7.a (fixes
   Les Sports)
 - IMPROVED: patchers/gamco.a (fixes
diff --git a/src/strings/en.a b/src/strings/en.a
index ced12d5..eb45717 100755
--- a/src/strings/en.a
+++ b/src/strings/en.a
@@ -220,6 +220,7 @@ StringTableLow            ; must be kept in sync with constants in enid.a
          !byte <.probs5
          !byte <.didatech
          !byte <.anychecksum
+         !byte <.unexpected5and3
 
 StringTableHigh           ; must be kept in sync with constants in enid.a
          !byte >.header
@@ -379,11 +380,12 @@ StringTableHigh           ; must be kept in sync with constants in enid.a
          !byte >.probs5
          !byte >.didatech
          !byte >.anychecksum
+         !byte >.unexpected5and3
 
 .passport
          !text "Passport ",$00
 .header
-         !text "@",s_passport,"by 4am@",s_space7,"@",s_space7," 2023-05-28",$00
+         !text "@",s_passport,"by 4am@",s_space7,"@",s_space7," 2023-06-26",$00
 .bar9
          !text "_________",$00
 .bar18
@@ -786,3 +788,5 @@ StringTableHigh           ; must be kept in sync with constants in enid.a
 .anychecksum
          !text "@",s_rwts,"@",s_acceptsany,$8D
          !text "address field checksum",$8D,$00
+.unexpected5and3
+         !text "@",s_tfound,"5-and-3 @",s_protectiontrack,$8D,$00
diff --git a/src/strings/enid.a b/src/strings/enid.a
index 52e2857..805a360 100644
--- a/src/strings/enid.a
+++ b/src/strings/enid.a
@@ -158,3 +158,4 @@ s_neosoft    = $99
 s_probs5     = $9A
 s_didatech   = $9B
 s_anychecksum = $9C
+s_unexpected5and3 = $9D
diff --git a/src/wholetrack.a b/src/wholetrack.a
index 3f7fa69..926bda2 100755
--- a/src/wholetrack.a
+++ b/src/wholetrack.a
@@ -39,6 +39,13 @@ SkipTrack
          lda   #s_sync
          bcc   @print
 ;
+; Unexepcted 13-sector track on a 16-sector disk?
+; (Micrograms likes to do this)
+;
+         jsr   Unexpected5And3InBaggingArea
+         lda   #s_unexpected5and3
+         bcc   @print
+;
 ; RW18-format track?
 ;
          jsr   VerifyInfocom18
@@ -312,3 +319,52 @@ Read4x4
   }
          and   tmp
          rts
+
+;-------------------------------
+; Unexpected5And3InBaggingArea
+; check if track is unexpectedly full of
+; 5-and-3-encoded sectors on a disk where
+; we expected 6-and-2 encoded sectors
+;
+; used by e.g. Micrograms as a weak form
+; of copy protection to foil COPYA-style
+; copying
+;
+; in  slot 6, drive 1 is on track to test
+; out C clear if unexpected track found
+;     C set if not found
+;-------------------------------
+Unexpected5And3InBaggingArea
+         lda   gIs13Sector
+         beq   @no                   ; if ID'd as a 13 sector disk, then this is not unexpected
+         lda   $C0E9
+         lda   #$19
+         sta   nibcount
+         ldx   #$0C
+         ldy   #$00
+@restart
+         dey
+         bne   +
+         dec   nibcount
+         beq   @no
++
+-        lda   $C0EC
+         bpl   -
+@maybeD5
+         cmp   #$D5
+         bne   @restart
+-        lda   $C0EC
+         bpl   -
+         cmp   #$AA
+         bne   @maybeD5
+-        lda   $C0EC
+         bpl   -
+         cmp   #$B5
+         bne   @maybeD5
+         dex
+         bne   @restart
+         clc                         ; passport-test-suite/Real Math.woz [C=0] matches
+         !byte $A9
+@no      sec
+         lda   $C0E8
+         rts