From 1ce44ea23418ddfe0c851d8a25f8a2fd7dcfa89c Mon Sep 17 00:00:00 2001
From: 4am <a2_4am@sent.com>
Date: Sun, 29 Oct 2017 21:00:15 -0400
Subject: [PATCH] add option to enforce address field checksum verification in
 built-in RWTS

---
 src/id/trace33.a | 1 +
 src/passport.a   | 5 +++++
 src/rwts.a       | 8 ++++++++
 src/strings/en.a | 2 +-
 4 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/id/trace33.a b/src/id/trace33.a
index 6e32d43..119e735 100755
--- a/src/id/trace33.a
+++ b/src/id/trace33.a
@@ -15,6 +15,7 @@ TraceDOS33
          sta   gTrack
          lda   #$09
          sta   gSector
+         jsr   IgnoreAddressChecksum
 precheck
          jsr   ReadSector
          bcc   +
diff --git a/src/passport.a b/src/passport.a
index c44f1e2..8a2aa0f 100755
--- a/src/passport.a
+++ b/src/passport.a
@@ -290,6 +290,7 @@ Action
          sta   TEXTTOP
          lda   #s_reading
          jsr   PrintByID
+         jsr   IgnoreAddressChecksum
          jsr   ReadSector
          bcc   +
          lda   #s_fail
@@ -508,6 +509,10 @@ StartWithUniv
 ; note: execution falls through here
 
 CopyUniversal
+         lda   #>EnforceAddressChecksum-1
+         pha
+         lda   #<EnforceAddressChecksum-1
+         pha
          lda   #$B8
 CopyUniversalAnywhere
          sta   dst+1
diff --git a/src/rwts.a b/src/rwts.a
index 69020ed..62fdc03 100755
--- a/src/rwts.a
+++ b/src/rwts.a
@@ -104,6 +104,14 @@ PreReadSector
 .exit    rts
 }
 
+IgnoreAddressChecksum
+         lda   #$00
+         !byte $2C        ; hide next LDA
+EnforceAddressChecksum
+         lda   #$B7
+         sta   $B98A
+         rts
+
 gTrack   !byte $00
 gSector  !byte $00
 
diff --git a/src/strings/en.a b/src/strings/en.a
index 1e422ef..0c861d1 100755
--- a/src/strings/en.a
+++ b/src/strings/en.a
@@ -234,7 +234,7 @@ StringTable
 ; can be set directly before calling PrintByID.
 ;
 .header
-         !text "Passport by 4am               2017-10-26",$00
+         !text "Passport by 4am               2017-10-29",$00
 .mainmenu
          !text "________________________________________",$8D,$8D,$8D,$8D,$8D,$8D,$8D
          !text "              "