System information

FUNCTION 34: WRITE RANDOM

Entry Parameters:

Registers DE: FCB Address

Returned Value:

The Write Random operation is initiated similarly to the Read Random call, except that data is

written to the disk from the current DMA address. Further, if the disk extent or data block that is

the target of the write has not yet been allocated, the allocation is performed before the write

operation continues. As in the Read Random operation, the random record number is not

changed as a result of the write. The logical extent number and current record positions of the

FCB are set to correspond to the random record that is being written. Again, sequential read or

write operations can begin following a random write, with the notation that the currently

addressed record is either read or rewritten again as the sequential operation begins. You can also

simply advance the random record position following each write to get the effect of a sequential

write operation. Note that reading or writing the last record of an extent in random mode does not

cause an automatic extent switch as it does in sequential mode.

The error codes returned by a random write are identical to the random read operation with the

addition of error code 05, which indicates that a new extent cannot be created as a result of

directory overflow.

5.2 Call Conventions CP/M Operating System Manual

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