Linux Toys
Official Penguin
I/O devices for your Linux PC.

Contents
  - 6-headed Linux
  - AJAX Tutorial
  - /dev/fanout
  - A $10 Answering Machine
  - 1 Bit Data Scope
  - X IR RC
  - ProbeScope
  - RS232 DVM
  - RS232 Keypad

Linux Toys

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Contents



Build a Six-headed, Six-user Linux System
A multi-headed, multi-user Linux system is a great way to reduce the cost, noise, and power needed to support more than one user in a room. This article shows you how to build a six seat system that can run six independent instances of Gnome or KDE.

The system described above had a problem which is fixed in the recent nVidia drivers. The system should work for you. Here are some simplified instructions for installing a dual seat system on Ubuntu.


A Short Tutorial on XMLHttpRequest()
Using JavaScript's XMLHttpRequest() you can asynchronously update a web page with the response to a web request. This short tutorial shows how to use XMLHttpRequest() to asynchronously display the output of a named pipe (FIFO) on a web page.

/dev/fanout : A One-To-Many Multiplexer
The fanout device is a FIFO that copies its input to all processes that are reading from it, making it a one-to-many multiplexer. Fanout may be that simple, broadcast IPC that you've been looking for.
A new version includes a bug fix and more comments by Edwin van den Oetelaar.

A $10 Linux Answering Machine
Build a Linux-based telephone answering machine using a ten dollar winmodem, open-source libraries, and our simple C program.

1 Bit Data Scope
The 1 Bit Data Scope captures one bit of data at a rate of 46080 (or 92160) samples per second and encodes the data into a stream of RS-232 characters which can be read by any computer at 57.6 (115.2) kilobaud. The Data Scope is a fairly simple construction project which uses six low cost IC's.
1bitds is a Tcl/Tk program which gives an oscilloscope-like display of the data. Display modes include triggered, continuous, and one-shot, and it has a 1000-to-1 zoom range.

X Infrared Remote Control
The ELM622 by ELM Electronics is a preprogrammed PIC which converts commands from a Sony infrared remote control into a serial data stream. This project shows how to build a Linux IR receiver based on the ELM622 and how to use the receiver to control an X application such as xmms.

ProbeScope
ProbeScope and the OsziFOX are low-cost digital oscilloscopes that fit into a hand-held probe. This article reviews the ProbeScope, presents its serial protocol, and gives an X-windows program to display the 'scope traces. The X-windows program, xProbeScope, needs only Xlib.

Radio Shack DVM with RS-232
A review of the Radio Shack Digital Volt Meter that has RS-232 output. The article describes the DVM and the protocol, and gives a simple program to take reading once a minute.
Energizer or Duracell: An application note which measures the discharge curve of four brands of AAA batteries. Uses gnuplot to plot the curves.

RS-232 Keypad
A description and sample program for the Qtronix QX-022R serial keypad. The keypad has the "numeric" part of a standard keyboard but has an RS232 interface.