Separate header and trailers of Atari system_check chunk.

[cc65] / include / _pia.h

diff --git a/include/_pia.h b/include/_pia.h
index 582b842754094ea1fd970c87d12fca81e4d961e4..4b71ecfd4a02f1d3c7294bb64d6e7a68cfbf6c1c 100644 (file)
--- a/include/_pia.h
+++ b/include/_pia.h
@@ -1,9 +1,13 @@
 /*****************************************************************************/
 /*                                                                           */
-/*                                 _pia.h                                   */
+/*                                  _pia.h                                   */
 /*                                                                           */
-/*               Internal include file, do not use directly                 */
+/*                Internal include file, do not use directly                 */
 /*                                                                           */
+/* The Peripheral Interface Adapter (PIA) chip (a 6520 or 6820) provides     */
+/* parallel I/O interfacing; it was used in Atari 400/800 and Commodore PET  */
+/* family of computers, for joystick and some interrupts.                    */
+/* Sources; various + Wikpedia article on "Peripheral Interface Adapter".    */
 /*                                                                           */
 /*                                                                           */
 /* (C) 2000 Freddy Offenga <taf_offenga@yahoo.com>                           */
@@ -34,7 +38,7 @@
 #define __PIA_H
 
 
-/* Define a structure with the pia register offsets */
+/* Define a structure with the PIA register offsets */
 struct __pia {
     unsigned char   porta;  /* port A data r/w */
     unsigned char   portb;  /* port B data r/w */
@@ -42,10 +46,7 @@ struct __pia {
     unsigned char   pbctl;  /* port B control */
 };
 
-
+/* (Some specific register values for Atari defined in atari.h) */
 
 /* End of _pia.h */
 #endif
-
-
-