text: /*
   * Memory and machine-specific definitions.  Used in C and assembler.
   */
  
  /*
   * Sizes
   */
  #define	BI2BY		8			/* bits per byte */
  #define	BI2WD		32			/* bits per word */
  #define	BY2WD		4			/* bytes per word */
  #define	BY2PG		4096			/* bytes per page */
  #define	WD2PG		(BY2PG/BY2WD)		/* words per page */
  #define	PGSHIFT		12			/* log(BY2PG) */
  #define	PGROUND(s)	(((s)+(BY2PG-1))&~(BY2PG-1))
  
  #define	MAXMACH		1			/* max # cpus system can run */
  
  /*
   * Time
   */
  #define	HZ		(20)				/* clock frequency */
  #define	MS2HZ		(1000/HZ)			/* millisec per clock tick */
  #define	TK2SEC(t)	((t)/HZ)			/* ticks to seconds */
  #define	TK2MS(t)	((((ulong)(t))*1000)/HZ)	/* ticks to milliseconds */
  #define	MS2TK(t)	((((ulong)(t))*HZ)/1000)	/* milliseconds to ticks */
  
  /*
   * Fundamental addresses
   */
  
  /*
   *  Address spaces
   *
   *  Kernel is at 0x00008000
   */
  #define	KZERO		0x00000000		/* base of kernel address space */
  #define	KTZERO		KZERO			/* first address in kernel text */
  #define	MACHSIZE	4096
  