  Implications of raising TTY_TYPAHDSIZ? 
 The Question is:
 
In system parameters,tty_typahdsz has a system default of 78, is there a
certain reason for this number?  What type of problems might I encounter if
I set this to 1024 or max it at 32768.  The reason I ask, because I am
unable to use tty_altypahd with lat
 ports (DEC9000 Terminal Server) so I am forced to use the type ahead
buffer.  I need the increase size to avoid data overrun errors.
 
 
 The Answer is:
 
  The origins of the choice of the value of 78 for the TTY_TYPAHDSZ system
  parameter are lost in the mists of time.
 
  The OpenVMS Wizard does not believe there are any reasons that would
  preclude raising the value to several hundreds of characters.
 
  Realize that larger values can cause the terminal driver (TTDRIVER) to
  spend extremely long intervals at elevated IPLs, potentially causing an
  adverse impact on the operation of the system.
 
