What is the JavaDive

JavaDive is a set of methods which allows Java applets to get access to the hardware I/O ports and COM/LPT ports directly, without drivers. These methods will be helpful for application developers for working with industrial hardware, modems, and other devices.

The history of JavaDive

These methods were developed for industrial machine which "breeds" plastic elements from fluid polymer. Such machines are utilized for medicine, criminology and other scientific and manufacturing branches.
In order to do its simpler, all devices - microprocessors, I/O cards and others, - were connected to the usual IBM PC computer through the motherboard slots. A good application was demanded to control the machine, the application which could work without any glitches during several days and weeks.

The shell

When I began this job, I already had the experience of applet development and my own sources for various tasks - from network computing to business applications. Java is a stable system, applets looks better than usual applications, they works slowly - but I did not demand a quick execution. So, Java was chosen for shell and I developed the applet for our machine.

The hardware access

Generally for access to I/O ports we must use a driver, which works in the "second ring" of 386 processor and can do more than other applications in the outer, "third" ring.
Can the user application work likewise a driver? This is possible for OS/2 Warp. I found a small DLL which allowed me to "dive" to the second ring and leave it. This DLL was written by russian hacker, Rinat Sadretdinov on pure Assembler and distributed as Public Domain.
I was very glad to use this library and connected it to my applet.

The JavaDive

I developed the Java class named "Dive" which provides the well-known "inp" and "outp" methods. When these methods reads or writes bytes, the applet "dives" to the second ring, and leave it after this action. This applet cannot work in the Netscape and I launch it as application.
To debug the class I tried to kick a PC Speaker via port number 0x61. Soon it became to merry grunt and squeal. Also I teached my computer to blink me a lamp on the modem. This looks good, and you can see this curcus too - simply launch the JavaDive.cmd
The Java 1.1.* and OS/2 Warp are required.

Any questions about assembler and IOPL32 - to Rinat,
Any questions about Java and this article - to me.
Yours Sergey Posokhov
- March 1999 -