McIDAS Programmer's Manual
Version 2003

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For a short history of McIDAS, read the Preface.


Copyright© 1997, 1998, 1999, 2003 Space Science and Engineering Center (SSEC)
University of Wisconsin - Madison
All Rights Reserved

Permission is granted to make and distribute verbatim copies of this document, provided the copyright notice and this permission are preserved on all copies.

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There is no expressed or implied warranty made to anyone as to the suitability of this software for any purpose. All risk of use is assumed by the user. Users agree not to hold SSEC, the University of Wisconsin-Madison, or any of its employees or assigns liable for any consequences resulting from the use of the McIDAS software.

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The information in this document is subject to change without notice. Considerable effort has been expended to make this document accurate and complete, but SSEC cannot assume responsibility for inaccuracies, omissions, manufacturers' claims or their representations.



McIDAS Programmer's Manual



McIDAS (Man computer Interactive Data Access System) is a set of tools for obtaining, analyzing, displaying and integrating environmental data. Its design focuses on four attributes:

The Space Science and Engineering Center (SSEC) of the University of Wisconsin-Madison has actively developed McIDAS software since the early 1970s.

McIDAS was originally developed on a Raytheon-440 computer using punch cards, paper tape and magnetic tape. It provided animation, display and analysis of geostationary meteorological satellite data. Later, the code was moved to Harris minicomputers in a distributed network, with two data servers and several applications boxes. Radar, meteorological observations and forecasts were added to the system. McIDAS' ability to provide real-time access to satellite and conventional data made it appealing to the meteorological forecast community.

As the amount of McIDAS code grew, it needed more processing power to ingest data, run larger applications and simultaneously serve more users. Thus, it was centralized onto an IBM mainframe running the MVS operating system.

Prior to McIDAS-MVS, workstations connected to the mainframe were considered dumb with most processing done on the mainframe. The workstation handled only simple controls such as changing frames, activating looping and positioning the cursor. With McIDAS-MVS in place, the first smart workstation was developed on DOS-based personal computers. These machines front-ended display hardware, such as the tower workstation. There were very few local applications, since the necessary multitasking was simulated in the McIDAS software.

The first large-scale port of applications software occurred when the OS/2 operating system was embraced for PCs. This was the beginning of McIDAS-OS2. Efforts to create an environment similar to the mainframe resulted in a smooth port of many applications. However, some changes were needed to accommodate special hardware; for example, VGA displays had only 16 color/gray levels. In addition, drivers were written for each display head: VGA, tower, WIDE WORD and SDA. These drivers had to appear to the applications as the same kind of raster-oriented device, with some varying characteristics such as frame size and number of colors. Communications drivers satisfying all applications were also needed for the common modes: asynchronous, ProNET and TCP/IP.

McIDAS-OS2's success led to the migration of McIDAS to the Unix environment. McIDAS users wanted support for applications on these faster, larger hardware platforms. The first attempt at this migration was taking the OS/2 code and writing specialized routines for the keyboard, mouse, text display, and image/graphics display, plus the system-level interfaces required for communications and disk I/O. The result was McIDAS-X.

Except for the ASK command and the Graphical User Interface, the implementation of McIDAS-X was done using the X Window System. To support McIDAS-X on more platforms and have it adhere to industry standards, the base code was changed significantly to make it more portable and less platform- and vendor-dependent.

Today, McIDAS is a fully distributed, workstation-based system. It generates multicolored composites of conventional and satellite weather data in a variety of displays in two and three dimensions as well as time-lapse sequences of these analyses. Designed to handle large amounts of meteorological imagery and other atmospheric data in a convenient manner, the system provides a vast resource of image-processing and applications programs. McIDAS hardware and software is used worldwide.


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