Using Both DOS and Windows.

Under DOS, programs were limited to about one megabyte of memory. This meant that the DOS compiler and loop closer could only process 5000 shots or between 15 to 20 miles of cave in a single file. In addition, the number of loop closures and the number of suspended shots were limited to 500 in any file.

If the cave got bigger than 5000 shots, 500 closures or 500 suspended shots, the data had to be broken down into separate files that held fewer shots, closures or suspended shots. Also, early versions of Compass for DOS required that all survey files be linked together, no matter how many surveys were in them. This made large caves somewhat complicated to work with.

The Windows version does not have any of these limitations, so if you are working exclusively with the Windows version, there is no limit on the size of the files. (However, for very large caves, you probably want to keep the data for different sections in separate files for easier handling of the data and better organization.) You are also free to remove any links as long as there are no duplicate station names between files.

This leads to two issues. First, you may have some files that were originally generated in the DOS version that you are now using exclusively in Windows. Second, you have some files that were generated in Windows that you want to use with DOS.

1. DOS Originated Files. Files and projects created under the DOS version can be used with no conversion whatsoever under the Windows version. However, if the survey has been arbitrarily broken into separate files, you might want to combine them or remove links, for efficiency sake. To remove links, simply use the link editing features of the Project Manager.

To combine files, you should use the Merge File feature of Compass. You can also combine files or parts of files using the Project Managers Survey Manipulation features.

Problems Combining Files. Several problems can occur when you combine files. First, you will have problems if any two files use the same survey name. For example, if GROANING.DAT and FIXING.DAT both have a "B" survey, shots in both "B" surveys will conflict with each other if you combine the files. This is because when the surveys are in separate files and you use linking, the two "B" surveys are invisible to each other. There are two solutions to this problem. Either don't combine the two file or rename all the stations in one of the conflicting surveys.

Another problem that occurs when combining files is “station shifts.” When you link two files together, you get to choose the linking stations between the files. Compass only needs one link between cave segments; however, there may be several additional connections between the segments. When you combine two files, all these connections are automatically used. The new connection’s path may have more or less errors on them than the original link. These differences will cause any stations downstream from the connections to change position. This is generally a minor problem caused by survey errors. Closing the loops before compiling will resolve the problem.

Reason For Not Combing Files. Even though you can now compile virtually any cave or cave system as a single file, it is still useful to keep parts of the cave in separate files. One reason for keeping separate files is for organization. Having caves or parts of caves in separate files allows you to create several different project files that show different aspects of the caves. For example, there are about eight different caves in the Williams Canyon area. There are also several different surface surveys. I keep each cave and each surface survey in a separate file. I have several different Projects that allow me to view various combinations of all or part of the caves and surface surveys.

Finally, compiling linked files is slightly fast than processing a single combined file. This is because the program doesn't have to search through so many station names when it is processing separate files. However, Windows’ computers are so fast these days, that the slight speed increase is pretty trivial.

2. Windows Originated Files. If you are planning to use Windows survey data under DOS, you may have to break your files up into smaller segments. This will be necessary if the files have more than 5000 shots or more than about 15 to 20 miles of cave. You can do this by using the Project Manager’s Survey Manipulating Tools. You will also have to create links between files. For further information, please refer to the Compass for DOS manual entitled Compass.TXT.