intro_intra_node_io

	Several routines are available for intra-node communication between
	console programs.  The messages are passed via mailboxes.
	'cmu_connect' connects a process to a specified mailbox.  Messages
	can then be sent and received with 'cmu_send' and 'cmu_receive'.  
	'cmu_disconnect' then allows detaching from a mailbox.  Callbacks
	can be specified for message notification.   Because of this, it is
	up to the user to use one mailbox to receive messages and another
	box to send messages.  Presently, the maximum message length is
	2048 bytes.
	
	See console page D111 (MAILTEST) for use of these CMU routines.

	'send_rsx', 'receiv_rsx' and 'lrdast' allow a task to send, receive
	or check for messages from other applications.

	See also 'intro_acnet'.

	These functions require the following include files:

	clib_h

	Related functions:

	cmu_connect, cmu_disconnect, cmu_empty_box, cmu_receive, cmu_send,
	lrdast, receive_rsx, send_rsx