From 2c86e4809f5e9169a8630d614c06c1d44ba9ba71 Mon Sep 17 00:00:00 2001
From: Philip Zembrod <pzembrod@gmail.com>
Date: Sun, 31 Jul 2022 23:54:37 +0200
Subject: [PATCH] Remove references to the Kernal variables InDev and OutDev
 which are needed to implement BUSOFF via CLRCHN and which moved on X16
 between r38 and r41 and will likely change again, and replace with own
 variables and calls to UNLSN and UNTLK.

---
 6502/C64/src/vf-sys-c16.fth |  2 --
 6502/C64/src/vf-sys-c64.fth |  2 --
 6502/C64/src/vf-sys-cbm.fth | 14 +++++++++-----
 6502/C64/src/vf-sys-x16.fth |  2 --
 4 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/6502/C64/src/vf-sys-c16.fth b/6502/C64/src/vf-sys-c16.fth
index 3dd8d44..4c74e42 100644
--- a/6502/C64/src/vf-sys-c16.fth
+++ b/6502/C64/src/vf-sys-c16.fth
@@ -9,8 +9,6 @@ include vf-lbls-cbm.fth
 0ff4c >label ConOut
   090 >label IOStatus
   09a >label MsgFlg
-  099 >label OutDev
-  098 >label  InDev
 0ff19 >label BrdCol
 0ff15 >label BkgCol
  053b >label PenCol
diff --git a/6502/C64/src/vf-sys-c64.fth b/6502/C64/src/vf-sys-c64.fth
index 9eb05de..10e0082 100644
--- a/6502/C64/src/vf-sys-c64.fth
+++ b/6502/C64/src/vf-sys-c64.fth
@@ -9,8 +9,6 @@ include vf-lbls-cbm.fth
 0E716 >label ConOut
   090 >label IOStatus
   09d >label MsgFlg
-  09a >label OutDev
-  099 >label  InDev
 0d020 >label BrdCol
 0d021 >label BkgCol
  0286 >label PenCol
diff --git a/6502/C64/src/vf-sys-cbm.fth b/6502/C64/src/vf-sys-cbm.fth
index 260a63e..44a9d28 100644
--- a/6502/C64/src/vf-sys-cbm.fth
+++ b/6502/C64/src/vf-sys-cbm.fth
@@ -100,7 +100,7 @@ Output: display   [ here output ! ]
 87 fthpage
 
 Code i/o-status?  ( -- n )
-  IOStatus lda  Push0A jmp  end-code
+  READST jsr  Push0A jmp  end-code
 
 \ b/blk drive >drive drvinit  clv14:2x87
 
@@ -131,7 +131,12 @@ Variable (drv    0 (drv !
 
 Variable i/o  0 i/o !  \ Semaphore
 
-Code busoff  ( --)   CLRCHN jsr
+Label LsnDev 0 c,
+Label TlkDev 0 c,
+
+Code busoff  ( --)
+ LsnDev lda  0<> ?[ LsnDev stx  UNLSN jsr ]?
+ TlkDev lda  0<> ?[ TlkDev stx  UNTLK jsr ]?
 Label unlocki/o  1 # ldy  0 # ldx
  ;c:  i/o unlock ;
 
@@ -164,7 +169,7 @@ Label (?dev
  N 2+ lda  (?dev jsr
  N 2+ lda  LISTEN jsr
  N lda  60 # ora SECOND jsr
- N 2+ ldx  OutDev stx
+ N 2+ ldx  LsnDev stx
  xyNext jmp  end-code
 
 
@@ -188,8 +193,7 @@ Label (?dev
  N 2+ lda  TALK jsr
  N lda  60 # ora (C16 $ad sta ( )
  TKSA jsr
-\ because of error in old C16 OS
- N 2+ ldx  InDev stx
+ N 2+ ldx  TlkDev stx
  xyNext jmp end-code
 
 : busin  ( dev 2nd -- )
diff --git a/6502/C64/src/vf-sys-x16.fth b/6502/C64/src/vf-sys-x16.fth
index 18cbc7e..b472e7d 100644
--- a/6502/C64/src/vf-sys-x16.fth
+++ b/6502/C64/src/vf-sys-x16.fth
@@ -9,8 +9,6 @@ include vf-lbls-cbm.fth
 0febd >label KbdbufPeek
  0289 >label IOStatus
  028c >label MsgFlg
- 028e >label OutDev
- 028d >label  InDev
 09f2c >label BrdCol
  0266 >label BkgCol
  0284 >label PenCol