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WriteLED: Write to LED Display

Released Februar 2003

WriteLED is a small display utility for the LED display panel of the IBM PS/2 Server 95. It can be used to write a text made up of up to 8 characters to the LED display panel. WriteLED can be used on DOS, OS/2, Windows 95/98 and Windows NT.

WriteLED for Windows NT requires the MCPOS driver to operate properly. MCPOS must be started prior to the invocation of the program. By contrast, WriteLED for DOS is a standalone DOS program and does not require any additional drivers or utilities.

WriteLED uses the system LED display ports 108h thru 10Fh. Running WriteLED on a machine without a LED display panel should not have any adverse effects on the system integrity.

Program binaries and source code have been released for DOS and Windows NT. The source code is common to DOS and Windows NT, where platform-dependent sections are distinguished by the defined _WLEDDOS variable.

This release of WriteLED provides video effects like scrolling and blinking a text, and dumping a file to the LED display. The WriteLED package is available for download.

WriteLED Options

WriteLED is controlled through a number of command line options. To list all options and get a help information about the command line options, run writeled -h. To run the built-in WriteLED demo, execute writeled -d.

Always enclose text arguments in quotation marks. Text arguments are required by the options -o (output), -s (scroll) and -f (file). For example, this is a valid invocation: writeled -s "ooo Welcome to the machine ooo". When you precede your scrolling text by seven or more spaces, the text will enter the LED display from the rightmost cell.

The options -m (machine), -u (user) direct WriteLED to write the computer resp. user name on the display. Only the first 8 characters can be written, longer strings will be truncated. These options are available only in WriteLED for Windows NT.

As a special feature, WriteLED includes a file dump facility. Yes, you have read that correctly, you can dump the contents of any file to the LED display. Select a file to dump and run writeled -f <file name>, then enjoy your display. All control characters and repeating spaces in the file are intercepted and removed, resp. replaced by a single space character.

Known Problems

WriteLED will fail to write to the LED display panel of IBM Server 720. The reason is that the LED display panel of Server 720 uses a different and unknown to us display port address range.

Please report any problems or bugs.

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