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Virtual HP-IL

HP-IL (Hewlett Packard Interface Loop) is a system that permits communication between devices. They are connected over a simple 2-wire cable in a loop. HP-IL was designed as a small, low power, low cost, and medium distance interface that allows to produce portable calculators and peripherals. Nowadays we simulate handheld devices and some peripherals too. As such it makes no sense to save data for example on a 3½ inch floppy disk. It is more convenient to save it on a hard disk, flash memory or on an optical media. In addition hardware with an HP-IL interface (e. g. printer) is quite old and rare these days. To link the simulated substitute also the transport interface must be replaced. This is the idea behind "Virtual HP-IL".

In summer 2009 Jean-François Garnier published his PIL-Box project to link real HP-IL hardware with virtual devices on a PC. The PIL-Box itself is a piece of hardware connecting the HP-IL system with a PC via USB bus. On the PC a program called "HP-IL Peripheral emulator" (short ILPer) is simulating a printer and a mass storage device.

Jean-François Garnier wrote ILPer originally in Visual Basic. In 2010 I ported his sources with some improvements to Visual C. ILPer up to V1.35 was designed to work only in conjunction with the PIL-Box resulting in an isolated HP-IL solution which could not be used as an universal peripheral simulator. Now I added to ILPer V1.4 a TPC/IP interface, allowing to link many different simulated devices in one virtual HP-IL loop. This page shows an example of connecting two ILPer programs and an additional IL frame sniffer to a PIL-Box. The bridge between the "Virtual HP-IL" and the PIL-Box hardware is realized with the program ILPilbox.

Here a block diagram showing the typical configuration with ILPer before V1.4:

Block diagram with one virtual device on a PIL-Box

Following a block diagram showing the extended possibilities of combining the real with the virtual HP-IL world - even spread over several PCs - using TCP/IP:

Block diagram combining real and virtual devices

ILPer v1.41 The HP-IL Peripheral emulator for Win32 simulating a HP-IL printer and mass storage device. Source code included. 186KB

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