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HP-IL, Linux and the Internet
Posted by Howard Owen on 27 July 2005, 4:07 p.m.
In terms of computer networks, HP-IL is almost as retro as you can get. It's not as old as the ARPANET, but it's older than that network's transition from NCP to TCP-IP, an event that many consider to be the birthday of the Internet. HP-IL is also contemperaneous with DECNET phase II, ARCNET and Ethernet (depending on who you talk to).
It is, in any event, a very old networking stack. It's so old, that it's design probably predates the invention of the term "networking stack." (Though I can't find a reference to the first use of that phrase, HP-IL certainly predates the OSI layer model. It doesn't predate the idea of layering protocols in computer networks, however.) It is old enough that getting it working with a modern protocol suite is a challenge.
This is a quick implementation note describing how I set up Christoph Klug's HP-IL ISA card, JF Garnier's EMU41 and Slackware Linux to talk to each other. The network I built is depicted in the following diagram:
The critical stat is the number of ISA slots. In addition to Christoph's HP-IL board, I have two ISA HP-IB cards and an original HP 82793 HP-IL card. I can theoretically have them all plugged in at once on this system.
The OS running on this system is Slackware Linux 10.1. I chose this distribution because it was the one current Linux distro that nearly made it on to the Compaq when there was only 16MB of RAM installed. It also had the smallest installed size for a modern distro without X11.
FreeDOS is installed on a 80MB partition at the start of the disk. This MS-DOS clone in perpetually in beta. The version I installed is the latest release, 0.9 beta. I haven't tried to do anything fancy in the DOS environment because most of that is supplied in Linux. (See below)
EMU41 is installed in the FreeDOS partition. This is the registered version that supports Cristoph Klug's ISA card, as well as the HP82973A card. This software makes a lot of what I do in this environment possible.
DOSEMU is a virtual machine for DOS that runs under Linux. A VM is required since DOS programs like to bang on the hardware directly. Unix-like operating systems such as Linux don't approve of that sort of thing, so DOSEMU provides a software layer that DOS can abuse, while protecting the real hardware from harm. I have version 1.22 of DOSEmu installed under Slackware.
Edited: 27 July 2005, 7:50 p.m.
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