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HP-IL

From Alfawiki
Hewlett-Packard Interface Loop (HP-IL)
Company typePeripheral communication bus
IndustryComputer hardware
FoundedJanuary 1, 1980; 46 years ago (1980-01-01)
FounderHewlett-Packard
FatePhased out
Headquarters
Palo Alto
,
United States
Area served
Worldwide
ProductsHP-IL controllers, interfaces, peripherals, and test instruments
OwnerHewlett-Packard
ParentHewlett-Packard
Websitewww.hpmuseum.org

The HP-IL (Hewlett-Packard Interface Loop) was introduced by Hewlett-Packard in the early 1980s as a short-distance peripheral communication bus. It linked various devices—including printers, plotters, displays, storage units, and testing instruments—to programmable calculators such as the HP-41C, HP-71B, HP-75C/D, along with the Series 80 and HP-110 personal computers and ISA bus-based PCs.

Principles

The HP-IL system operated as a ring network where each device connected via two wires labeled in (for receiving data) and out (for sending data). A single device functioned as the controller, overseeing communication among all connected peripherals. The cabling utilized distinctive two-pin connectors with polarized D-shaped housings, facilitating straightforward daisy-chaining without requiring adapters.

For media access control, HP-IL employed a token passing mechanism. During startup, the controller issued an "Auto Address 1" command that circulated through the loop, prompting each device to assign itself a sequential address. This procedure allowed for identification of up to 31 devices on the network. Subsequently, the controller designated roles as "talkers" or "listeners": multiple listeners could receive data concurrently, whereas only one talker was permitted to transmit at any given time. Data transfers were conducted through "Send Data" commands sent from the talker to the listeners.

While most controllers had fixed roles, the HP-71B was capable of functioning either as a controller or as a device. Using the HP 82402 Dual HP-IL Adapter, it could manage multiple loops simultaneously, enhancing device management versatility.

Applications

Hewlett-Packard produced a range of peripherals designed for use with HP-IL, primarily focusing on printers and storage solutions tailored for calculators. The 82169A HP-IL/HP-IB Interface provided connectivity between HP-IL controllers and instruments using the HP-IB (GPIB or IEEE-488) standard, allowing integration with a wider array of test equipment. Although additional test instruments with IL interfaces were planned, only a limited number—such as the 3468A multimeter—were released before HP-IL was phased out.

In addition to HP-IB connectivity, Hewlett-Packard offered RS-232 and parallel input/output interfaces along with a prototype kit intended for custom interface development.

HP Calculator Applications

Several Hewlett-Packard calculators came equipped with HP-IL interfaces: some models like the HP-75C/D included built-in ports, while others used plug-in modules such as the HP82160A for the HP-41 series. Typical applications involved printing via the HP 82162A thermal printer and storing files on cassettes using the HP 82161A digital cassette drive. Calculators supported automatic input/output address allocation ("AUTOIO") to route commands to the first available peripheral; manual address assignment ("MANIO") was offered when multiple devices of identical type were connected.

HP-IL to HP-IB Interfacing

The 82169A interface converter enabled compact calculators to control multiple instruments on a conventional HP-IB bus commonly used in testing and measurement environments. It operated in two distinct modes: Translator mode for systems with a single controller (usually a calculator on HP-IL), and Mailbox mode when controllers existed on both buses.

In Translator mode, the converter joined the HP-IL loop as its final device, assigning itself an HP-IB address higher than all other devices on the loop; devices connected via HP-IB required addresses exceeding that of the converter. Manual address configuration was necessary if deviating from this arrangement.

Mailbox mode allowed controllers on both sides of the interface to communicate by exchanging messages through the converter’s buffer memory.

Controllers

Interfaces

  • HP 82164A HP-IL to RS-232C Interface (serial communication port)
  • HP 82165A HP-IL to GPIO Interface (general-purpose parallel port)
  • HP 82166A Compact HP-IL Converter for embedded GPIO applications
  • HP 82166C Prototyping Kit for the HP-IL Converter
  • HP 82169A Bidirectional HP-IL to HPIB Interface
  • HP 5061-3166 HP-IL to SCSI Interface
  • HP 82402 Dual HP-IL Adapter compatible with the HP-71B

Peripherals

  • HP 9114A/B Disk Drives
  • HP 82161A Tape Drive unit
  • HP 82162A Thermal Printer (HP-IL variant of the HP 82143A for use with the HP-41C)
  • HP 82163A/B Video Interface modules
  • HP 92198A 80-Column Video Interface produced by Mountain Computer
  • Acoustic Couplers (Modems) models HP 82168A and 92205M
  • Printers: HP 82905A/B series
  • HP 2225B ThinkJet Printer model
  • Graphics Plotter: HP 7470A (includes optional 003 HP-IL Interface)
  • Alphanumeric Graphics Thermal Printer models HP 2671A/G

Test Instruments

  • Logic Analyzers: HP 1630A/D/G and HP1631 (capable of acting as loop controllers)
  • Data Acquisition and Control Unit: HP 3421A
  • Digital Multimeters: HP 3468A/B (HP-IL versions derived from GPIB-enabled HP 3478A)
  • Frequency Counters: Models HP 5384A and HP 5385A with option 003 (HP-IL support)
  • Spectrum Analyzer: HP 8590A equipped with option 022 (HP-IL interface)
  • Gas Chromatograph: HP 5890 and Autosampler model HP 7673 featuring an HP-IL interface for instrument control and data logging via the HP 19405A Sampler/Event Control Module and controlled by the HP 3392A Integrator
  • Transmission Impairment Measuring Set: HP 4945A with Option 103
  • Signature Analyzer: Model HP 5006A with Option 030

Software

  • Development Module for HP-IL (plug-in Application ROM designed for the HP-41C)
  • Extended I/O Module: HP 82183A

Third-party Products

  • FSI164A, an HP-IL/RS-232C Interface by Firmware Specialists
  • Leitz IL-41 interface designed for Theodolite
  • CMT RAM Disc ranging from 128 to 512k, with optional RS-232 support
  • Ocean Scientific Analog-to-Digital Interface compatible with HP-IL
  • Direct Connect Modem 300 Plus, a combined Modem and Bar Code Reader device
  • PAC Hardware GMBH PAC-Screen: an 80-column/graphics video interface including parallel printer and mouse ports
  • Interloop devices such as #111 Repeater, #130 Twinax Terminator, #200 Step Motor Driver, and #210 IO Interface for the HP-IL system
  • Steinmetz & Brown SB10161A/2A Single/Dual 5¼" Disk Drives
  • Interface Instruments ADC71A Analog-to-Digital Converter

See also

References

  • Official specification documentation.
  • Information on IC variants including later models such as the 1LR4-0002 and 1ML7-0005.
  • Owner's Manual for the HP-41's HP 82160A module
  • Owner's Manual for the HP-71's HP 82401A module

External links

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