diff --git a/acia.h b/acia.h
index 96f7def..960824e 100644
--- a/acia.h
+++ b/acia.h
@@ -9,6 +9,7 @@ public:
 	uint8_t read(Memory::address);
 
 	ACIA(serialio &s): _serial(&s) {}
+	void set_device(serialio *s) { _serial = s; }
 
 	// status bits
 	//
@@ -55,6 +56,6 @@ protected:
 	virtual void write_data(uint8_t);
 
 private:
-	class serialio *_serial;
+	serialio *_serial;
 };
 #endif
diff --git a/flash_filer.cpp b/flash_filer.cpp
index d93d328..f4fdbd2 100644
--- a/flash_filer.cpp
+++ b/flash_filer.cpp
@@ -29,6 +29,38 @@ bool flash_file::seek(uint32_t pos)
 #endif
 }
 
+bool flash_file::more()
+{
+#if defined(USE_SPIFFS) || defined(USE_LITTLEFS)
+	return files[_fd].available() > 0;
+#else
+	return false;
+#endif
+}
+
+uint8_t flash_file::read() {
+#if defined(USE_SPIFFS) || defined(USE_LITTLEFS)
+	return files[_fd].read();
+#else
+	return 0xff;
+#endif
+}
+
+flash_file::operator bool() const {
+#if defined(USE_SPIFFS) || defined(USE_LITTLEFS)
+	return files[_fd];
+#else
+	return false;
+#endif
+}
+
+void flash_file::write(uint8_t b) {
+#if defined(USE_SPIFFS) || defined(USE_LITTLEFS)
+	files[_fd].write(b);
+	files[_fd].flush();
+#endif
+}
+
 bool flash_filer::start()
 {
 #if defined(USE_LITTLEFS)
@@ -50,30 +82,6 @@ void flash_filer::stop()
 #endif
 }
 
-bool flash_file::more()
-{
-#if defined(USE_SPIFFS) || defined(USE_LITTLEFS)
-	return files[_fd].available() > 0;
-#else
-	return false;
-#endif
-}
-
-uint8_t flash_file::read() {
-#if defined(USE_SPIFFS) || defined(USE_LITTLEFS)
-	return files[_fd].read();
-#else
-	return 0xff;
-#endif
-}
-
-void flash_file::write(uint8_t b) {
-#if defined(USE_SPIFFS) || defined(USE_LITTLEFS)
-	files[_fd].write(b);
-	files[_fd].flush();
-#endif
-}
-
 const char *flash_filer::advance() {
 #if defined(USE_SPIFFS) || defined(USE_LITTLEFS)
 	bool rewound = false;
diff --git a/flash_filer.h b/flash_filer.h
index 8af42e7..97b9bcc 100644
--- a/flash_filer.h
+++ b/flash_filer.h
@@ -1,7 +1,7 @@
 #ifndef __FLASH_FILER_H__
 #define __FLASH_FILER_H__
 
-#define MAX_FILES	3
+#define MAX_FILES	5
 
 class flash_file: virtual public serialio {
 public:
@@ -12,6 +12,7 @@ public:
 	virtual void write(uint8_t);
 
 	bool seek(uint32_t pos);
+	operator bool() const;
 
 private:
 	const uint8_t _fd;