A component of
the IBM Microkernel that provides services for configuration, access, and
management of hardware to user level device drivers in the Microkernel Services
run-time environment.
hashing
(1)
A method of transforming a search key into an address for the purpose of
storing and retrieving items of data. The method is often designed to minimize
the search time. (T) (2) The application of an algorithm to the records
in a data set to obtain a symmetric grouping of the records. Synonymous
with key folding. (3) In an indexed dataset, the process of transforming
a record key into an index value for storing and retrieving a record.
hash
table
A table of information that is accessed
by way of a shortened search key (the hash value). Using a hash table minimizes
average search time.
hash total
(1)
The result obtained by applying an algorithm to a set of heterogeneous data
for checking purposes; for example, a summation obtained by treating data
items as numbers. (T) (2) Synonym for control total.
header
(1) System-defined control information that
precedes user data. (2) The portion of a message that contains control information
for the message such as one or more destination fields, name of originating
station, input sequence number, character string indicating the type of
message, and priority level for the message.
high-performance
file system (HPFS)
In the OS/2 operating system,
an installable file system that uses high-speed buffer storage, known as
a cache, to provide fast access to large disk volumes. The file system also
supports the coexistence of multiple, active file systems on a single personal
computer, with the capability of multiple and different storage devices.
File names used with the HPFS can have as many as 254 characters. On larger
disks HPFS will out perform FAT with less fragmentation.
hot
key
(1) The key combination used to change from
one session to another on the workstation. (2) To jump, or hot key, from
a host session to an application on the workstation, or from the workstation
to the host session.
hot spot
The
area of a display screen that is activated to accept user input. Synonymous
with touch area.