Access the GTOPO30 data from:

   http://edcwww.cr.usgs.gov/landdaac/gtopo30/gtopo30.html


Download the GTOP30 data file and uncompress.  The resulting files should be like:
  E060N40.DEM
  E060N40.HDR
  E060N40.SRC 
  E060N40.DMW
  E060N40.PRJ  
  E060N40.STX
  E060N40.GIF  
  E060N40.SCH 

While in the directory, change all the files to lower case:
  /home/tsoeller/bin/file_lo_case

Rename the .dem file to .bil, e.g.,
  mv e060n40.dem e060n40.bil


To begin, the ARC/INFO processing must be within a valid ARC/INFO workspace.

In ARC/INFO run imagegrid:
  imagegrid e060n40 e060n40a


From the data providers (http://edcwww.cr.usgs.gov/landdaac/gtopo30/README.html#h15):
Notes and Hints for GTOPO30 Users

Because the DEM data are stored in a 16-bit binary format, users must be
aware of how the bytes are addressed on their computers.  The DEM data are
provided in Motorola byte order, which stores the most significant byte
first ("big endian").  Systems such as Sun SPARC and Silicon Graphics
workstations use the Motorola byte order.  The Intel byte order, which
stores the least significant byte first ("little endian"), is used on DEC
Alpha systems and most PCs.  Users with systems that address bytes in the
Intel byte order may have to "swap bytes" of the DEM data unless their
application software performs the conversion during ingest.  The statistics
file (.STX) provided for each tile gives the range of values in the DEM
file, so users can check if they have the correct DEM values stored on
their system.

Users of ARC/INFO or ArcView can display the DEM data directly after simply
renaming the file extension from .DEM to .BIL.  However, if a user needs
access to the actual elevation values for analysis in ARC/INFO the DEM must
be converted to an ARC/INFO grid with the command IMAGEGRID.  IMAGEGRID does
not support conversion of signed image data, therefore the negative 16-bit
DEM values will not be interpreted correctly.  After running IMAGEGRID, an
easy fix can be accomplished using the following formula in Grid:

   out_grid = con(in_grid >= 32768, in_grid - 65536, in_grid)

The converted grid will then have the negative values properly represented,
and the statistics of the grid should match those listed in the .STX file.
If desired, the -9999 ocean mask values in the grid could then be set to
NODATA with the SETNULL function.

It may be necessary to bring the elevation values into the same 
realm of the x-y values if the x-y values are in longitude/latitude,
i.e., decimal degrees.  This may be necessary if a shaded relief is
to be constructed.  Using an input grid named e060n40grd, do the
following in the ArcView Map Calculator.

([e060n40grd].float / 100000.asgrid)