diff --git a/docs/lang/preprocessor.md b/docs/lang/preprocessor.md
index dee5498e..9c0682df 100644
--- a/docs/lang/preprocessor.md
+++ b/docs/lang/preprocessor.md
@@ -54,6 +54,8 @@ The following features are defined based on the chosen CPU and compilation optio
 `CPUFEATURE_8080`, `CPUFEATURE_8085`, `CPUFEATURE_GAMEBOY`, `CPUFEATURE_Z80`,
 `CPUFEATURE_6502_ILLEGALS`, `CPUFEATURE_8085_ILLEGALS`, `CPUFEATURE_Z80_ILLEGALS`, `CPUFEATURE_Z80_NEXT` – 1 if given instruction subset is enabled, 0 otherwise
 
+* `ENCCONV_SUPPORTED` - 1 if the module `encconv` supports the function `to_screencode` and other related funtions, 0 otherwise.
+
 * `ENCODING_SAME` - 1 if the encodings `default` and `src` are the same, 0 otherwise.
 
 * `NULLCHAR_SAME` - 1 if the encodings `default` and `src` have the same string terminator, 0 otherwise.
diff --git a/docs/stdlib/encconv.md b/docs/stdlib/encconv.md
index 0915e6da..c5a8c421 100644
--- a/docs/stdlib/encconv.md
+++ b/docs/stdlib/encconv.md
@@ -31,6 +31,8 @@ Available only if one of the following is true:
 
 * the default encoding is `atascii`, the screen encoding is `atasciiscr`, and the platform is 6502-based
 
+You can test for the availability of this function using the `ENCCONV_SUPPORTED` preprocessor feature.
+
 #### byte from_screencode(byte)
 
 Converts a byte from the screen encoding to the default encoding.
@@ -39,6 +41,18 @@ If both encodings contain the character `¤`, then `from_screencode('¤'scr) ==
 
 Available only if `to_screencode` is available.
 
+#### void strz_to_screencode(pointer)
+
+Destructively converts a null-terminated string from the `default` encoding into the `scr` encoding. 
+
+Available only if `to_screencode` is available.
+
+#### void strz_from_screencode(pointer)
+
+Destructively converts a null-terminated string from the `scr` encoding into the `default` encoding. 
+
+Available only if `from_screencode` is available.
+
 #### byte petscii_to_petscr(byte)
 
 Converts a byte from PETSCII to a CBM screencode.  
diff --git a/include/encconv.mfk b/include/encconv.mfk
index acb35ea5..e66492ed 100644
--- a/include/encconv.mfk
+++ b/include/encconv.mfk
@@ -2,23 +2,88 @@
 
 #if ARCH_6502
 inline byte __byte_identity(byte a) { ? rts }
+inline void __pointer_to_void(pointer ax) { ? rts }
 #elseif ARCH_I80
 #pragma zilog_syntax
 inline byte __byte_identity(byte a) { ? ret }
+inline void __pointer_to_void(pointer hl) { ? ret }
+#elseif ARCH_M6809
+inline byte __byte_identity(byte b) { ? rts }
+inline void __pointer_to_void(pointer d) { ? rts }
 #else
 inline byte __byte_identity(byte a) = a
+inline void __pointer_to_void(pointer a) { }
 #endif
 
 alias from_screencode = __byte_identity
 alias to_screencode = __byte_identity
+alias strz_from_screencode = __pointer_to_void
+alias strz_to_screencode = __pointer_to_void
 
-#else
+#elseif ENCCONV_SUPPORTED
 
 alias from_screencode = __from_screencode
 alias to_screencode = __to_screencode
 
+
+#if ARCH_6502
+void strz_from_screencode(pointer p) {
+    asm {
+        ? LDY #0
+        __strz_from_screencode__loop:
+        LDA (p),Y
+        ? CMP #nullchar_scr
+        ? BEQ __strz_from_screencode__end
+        ? JSR from_screencode
+        ? STA (p),Y
+        ? INY
+        ? JMP __strz_from_screencode__loop
+        __strz_from_screencode__end:
+        ? LDA #nullchar
+        ? STA (p),Y
+    }
+}
+void strz_to_screencode(pointer p) {
+    asm {
+        ? LDY #0
+        __strz_to_screencode__loop:
+        LDA (p),Y
+        ? CMP #nullchar
+        ? BEQ __strz_to_screencode__end
+        ? JSR to_screencode
+        ? STA (p),Y
+        ? INY
+        ? JMP __strz_to_screencode__loop
+        __strz_to_screencode__end:
+        ? LDA #nullchar_scr
+        ? STA (p),Y
+    }
+}
+#else
+void strz_from_screencode(pointer p) {
+    while true {
+        if p[0] == nullchar_scr {
+            p[0] = nullchar
+            return
+        }
+        p[0] = from_screencode(p[0])
+        p += 1
+    }
+}
+void strz_to_screencode(pointer p) {
+    while true {
+        if p[0] == nullchar {
+            p[0] = nullchar_scr
+            return
+        }
+        p[0] = to_screencode(p[0])
+        p += 1
+    }
+}
 #endif
 
+#endif // ENCODING_SAME/ENCCONV_SUPPORTED
+
 
 // conversions for particular encoding pairs:
 
diff --git a/src/main/scala/millfork/Platform.scala b/src/main/scala/millfork/Platform.scala
index f1295958..1e9531d5 100644
--- a/src/main/scala/millfork/Platform.scala
+++ b/src/main/scala/millfork/Platform.scala
@@ -282,6 +282,13 @@ object Platform {
 
     val builtInFeatures = builtInCpuFeatures(cpu) ++ Map(
       "ENCODING_SAME" -> toLong(codec.name == srcCodec.name),
+      "ENCCONV_SUPPORTED" -> toLong((codec.name, srcCodec.name) match {
+        case (TextCodec.Petscii.name, TextCodec.CbmScreencodes.name) |
+             (TextCodec.PetsciiJp.name, TextCodec.CbmScreencodesJp.name) |
+             (TextCodec.Atascii.name, TextCodec.AtasciiScreencodes.name) =>
+          CpuFamily.forType(cpu) == CpuFamily.M6502
+        case _ => codec.name == srcCodec.name
+      }),
       "NULLCHAR_SAME" -> toLong(codec.stringTerminator == srcCodec.stringTerminator)
     )