HDH(4)                                                                  HDH(4)



NAME
       hdh - ACC IF-11/HDH IMP interface

SYNOPSIS
       pseudo-device imp
       device hdh0 at uba0 csr 166740 vector hdhintr

DESCRIPTION
       The  _h_d_h device provides an HDLC Host (HDH) interface to an IMP.  It is
       normally used when participating in the DARPA Internet.  The controller
       itself  is  not  accessible to users, but instead provides the hardware
       support to the IMP interface described in  _i_m_p(4).   When  configuring,
       the _i_m_p pseudo-device must also be included.

DIAGNOSTICS
       hdh%d:  not  alive.  The initialization routine was entered even though
       the device did not autoconfigure.  This indicates a system problem.

       hdh%d: cannot get chan %d uba resources.  Insufficient UNIBUS resources
       existed  to  initialize the device.  This is likely to be a shortage of
       UNIBUS mapping registers.

       hdh%d: LINE UP.  This indicates that both the HDLC  and  HDH  protocols
       have declared the link to the IMP alive.

       hdh%d: LINE DOWN.  This indicates that the link to the IMP has died.

       hdh%d: HOST SEQUENCE ERROR
       hdh%d: IMP SEQUENCE ERROR
       hdh%d: HOST DATA ERROR
       hdh%d: TIMEOUT
       These errors indicate that an HDH protocol error has been detected.

       hdh%d: cannot get supervisor cmnd buffer.  This error indicates that an
       _m_b_u_f could not be allocated to send a command to the IF-11/HDH.

       Any other error message from hdh%d: indicates a serious error  detected
       by either the driver or the IF-11/HDH firmware.



4.3 Berkeley Distribution       August 8, 1985                          HDH(4)