User`s guide

Error Code 01 is returned if no data exists at the next record position of the file.

Usually, the no data situation is encountered at the end of a file. However, it can

also occur if an attempt is made to read a data block that has not been previously

written, or an extent which has not been created. These situations are usually restricted

to files created or appended with the BDOS random write functions (see Functions

34 and 40).

Error Code 09 is returned if the FCB is invalidated by a previous BDOS close call that

returns an error.

Error Code 10 is returned if a media change occurs on the drive after the refer-

enced FCB is activated by a BDOS Open, or Make Call.

Error Code 255 is returned if a physical error is encountered and the BDOS error

mode is Return Error mode, or Return and Display Error mode (see Function 45). If

the error mode is the default mode, a message identifying the physical error is dis-

played at the console, and the calling program is terminated. When a physical error

is returned to the calling program, register H contains one of the following error

codes:

01 Disk I/O error

04 Invalid drive error

On all error returns except for physical error returns, A = 255, Function 20 sets

This value can range from 0 to 127 depending on the current BDOS Multi-Sector

Count. It is always set to zero when the Multi-Sector Count is equal to one.

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BDOS Function Calls CP/M 3 Programmers Guide