<
hardware, standard> (GPIB, General-Purpose Interface Bus,
HP-IB, Hewlett-Packard Interface Bus) An 8-bit parallel
bus
common on
test equipment.
The IEEE-
488 standard was proposed by
Hewlett-Packard in the
late 1970s and has undergone a couple of revisions. HP
documentation (including data sheets and manuals) calls it
HP-IB, or Hewlett-Packard Interface Bus.
It allows up to 15 intelligent devices to share a single bus,
with the slowest device participating in the control and data
transfer handshakes to drive the speed of the transaction.
The maximum data rate is about one
megabit per second.
Other standards committees have adopted HP-IB (American
Standards Institute with ANSI Standard MC 1.1 and
International Electro-technical Commission with IEC
Publication 625-1).
To paraphrase from the HP 1989 Test & Measurement Catalog (the
50th Anniversary version): The HP-IB has a party-line
structure wherein all devices on the bus are connected in
parallel. The 16 signal lines within the passive
interconnecting HP-IB (IEEE-
488) cable are grouped into three
clusters according to their functions (Data Bus, Data Byte
Transfer Control Bus, General Interface Management Bus).
In June 1987 the IEEE approved a new standard for programmable
instruments called IEEE Std. 488.2-1987 Codes, Formats,
Protocols, and Common Commands. It works with the IEEE
Standard Digital Interface for Programmable Instrumentation,
IEEE
488-1978 (now 488.1). HP-IB is Hewlett-Packard's
implementation of IEEE 488.1.
(1996-05-10)