RNDINIT - Initialize Random Number Generator Seed

  ENTER: None
  EXIT : None
  USES : None

 Usage:  Version 4 of the Libraries changes this function from
  the Keyboard/Loop counter used in previous versions to one
  where the Refresh register of the Z80/Z180 is read to form
  the initial seed, requiring no user action. This method will
  NOT work on the Z280 where REFRESH is just another register.

 RNDSEED - Set Known Seed Value

  ENTER:  A = 8-bit Seed Value
  EXIT : None
  USES : None

 Usage:  This routine allows you to provide a seed value for
  the random number generator instead of using the automatic
  method in RNDINIT.

RND - Return 8-bit Pseudo-Random Number

  ENTER: None
  EXIT :  A = Random Number
  USES : AF

 Usage:  This routine is the one to call to obtain a pseudo-
  random byte.  The returned values are between Zero and 255.
  You must do any scaling needed for your application.