This chapter provides a reference for all MFS calls. Included in this chapter are:
Parameters for all seven MFS arguments as they are passed by BASIC+, and as they are returned by the BFS
Information on the commands in OpenInsight that invoke specific calls
Notes on the implementation of the calls and on disabling them
MFS Operations Glossary
The following terms are used in the MFS Operations Reference:
Term | Meaning |
Input | A value as passed from BASIC+. Another MFS may modify this value before an MFS receives it. |
Output | A value as returned from the BFS. Another MFS may modify this value before an MFS receives it. |
null | An argument passed with no value from BASIC+. |
unassigned | An argument passed unassigned from BASIC+. An attempt to use this argument before initializing it will result in an error. |
unchanged | An indication that the BFS makes no change to the value(s) passed in this argument, although the value may be used by other filing systems. |
BFS List | The list of filing systems (MFS and BFS) not yet called to access the current file or media map. (As a filing system is called, it removes itself from this list.) The values in this list are delimited with subvalue marks (@SVM). |
volume qualifier Information | Information about the actual physical location of a file or media map (almost always the subdirectory path of the file or media map), or field three of volume pointer in the VOC file for the current file or media map. |
Called by | The primary means to access this MFS call. This is either the BASIC+ command that generates the MFS call, or if no BASIC+ command is available, the System Monitor command(s) that provides primary access to the MFS call. The phrase "direct access only" indicates that there is neither an BASIC+ nor System Monitor command that uses the call, and that it is available only by calling the filing system directly or through a system subroutine. |
True | 1 |
False | 0 |
READ.RECORD
Purpose | Used to read a record directly from a file. | |||||||||||||||||||||||||||||||||||||||||||||
Arguments |
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Called by | BASIC+ READ statement |
READO.RECORD
Purpose | Used to read a record that will not be updated (read only). This code is provided for filing systems that might use buffers to store records already read. In an MFS, this code is typically implemented in the same manner as a READ code, with all arguments passed through to subsequent filing systems as if the code were READ.RECORD. | |||||||||||||||||||||||||||||||||||||||||||||
Arguments |
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Called by | BASIC+ READO statement |