National Aeronautics and Space Administration

For MHER7, the data samples are 4 bits long and are stored such that the time increases more rapidly than the energy range. One record thus contains data for all the (1, 2 or 4) selected ranges. For MHTR4 the samples are 1 bit long, ie. the value 1 indicates that an event within the selected energy range occurred. For MHTR5 the samples are again 4 bits long. The value 15 for a four bit counter means "greater than or equal to 15".

In all cases information is stored to tape in chronological order of its reception on the ground, which means (for users of HP and IBM computers) in order of decreasing significance within a memory buffer. This applies at the bit level as well as the byte level. Users of DEC computers must take special care that samples are accessed in the correct order, because their address convention at the byte level differs from the convention used in OBC and FOT documentation. Within a byte, the "decreasing significance" convention applies to all computers, eg. the first sample of an MHTR4 record should be extracted from the most significant bit of a byte.