From 3e6d9c41db81355d1a99d8a225cf9461a80ca1cf Mon Sep 17 00:00:00 2001
From: Peter Ferrie <peter.ferrie@gmail.com>
Date: Wed, 13 Mar 2019 16:23:54 -0700
Subject: [PATCH 1/2] distinguish better between 13- and hybrid-boot

---
 src/idboot.a | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/idboot.a b/src/idboot.a
index e2b22f4..bb59357 100644
--- a/src/idboot.a
+++ b/src/idboot.a
@@ -11,8 +11,7 @@ IDBoot
          sta   $867B
 
 ; found D5 AA 96 T00S00 D5 AA AD, proceed as 16-sector
--        clc
-         jmp   $865D
+-        jmp   $865C
 
 ; found D5 AA not-96
 ; check for out-of-order D5 AA AD
@@ -23,6 +22,19 @@ IDBoot
          cmp   #$B5
          bne   -
 
+; found D5 AA B5, try to read address field
+         lda   #$60
+         sta   $8699
+         ldy   #3
+         jsr   $868F
+         lda   #$28
+         sta   $8699
+
+; non-zero track suggests copy-protection
+; proceed as 16-sector instead
+         lda   $40
+         bne   --
+
 ; found D5 AA B5, assume 13-sector
          lda   #$90
          sta   $867B

From 3ffcfeb6721c89bb8741716be71bd56ce45e3913 Mon Sep 17 00:00:00 2001
From: Peter Ferrie <peter.ferrie@gmail.com>
Date: Wed, 13 Mar 2019 16:57:08 -0700
Subject: [PATCH 2/2] fix the hybrid corner-case

seeing 13 D5 AA B5 in a row, and then the D5 AA 96
---
 src/idboot.a | 35 ++++++++++++++++-------------------
 1 file changed, 16 insertions(+), 19 deletions(-)

diff --git a/src/idboot.a b/src/idboot.a
index bb59357..49c1479 100644
--- a/src/idboot.a
+++ b/src/idboot.a
@@ -5,37 +5,34 @@ IDBoot
 ; try to determine sector type based on found boot sector
          lda   #$60
          sta   $867B
-         jsr   $8600
+@patch
+         jsr   $8600 ;SMC
+         ldy   #$5C
+         sty   @patch+1
          bcc   +
---       lda   #$90
+         lda   #$90
          sta   $867B
 
 ; found D5 AA 96 T00S00 D5 AA AD, proceed as 16-sector
--        jmp   $865C
+         bne   @patch ;always
+
+@retries
+         !byte 14 ;sectors per track+1 to cover the corner-case
 
 ; found D5 AA not-96
-; check for out-of-order D5 AA AD
+; check for out-of-order D5 AA AD, and retry in that case
 +        cmp   #$AD
-         beq   --
+         beq   @patch
 
 ; otherwise, loop in case we will see D5 AA B5
          cmp   #$B5
-         bne   -
+         bne   @patch
 
-; found D5 AA B5, try to read address field
-         lda   #$60
-         sta   $8699
-         ldy   #3
-         jsr   $868F
-         lda   #$28
-         sta   $8699
+; and loop anyway in case it's a hybrid disk and we missed the D5 AA 96
+         dec   @retries
+         bne   @patch
 
-; non-zero track suggests copy-protection
-; proceed as 16-sector instead
-         lda   $40
-         bne   --
-
-; found D5 AA B5, assume 13-sector
+; found nothing but D5 AA B5, proceed as 13-sector
          lda   #$90
          sta   $867B