Compatibility: 1.0+
Expects: AH    15H
DS:DX address of an opened FCB
Returns: AL    0 if the write was successful
1 if "disk full" error and no data was written
2 if DTA+ FCB recSize would overrun a segment (no write)
Info: Writes recSize bytes from the DTA to the file address specified
by curBlk and curRec (as specified in the FCB).  Then increments
the block-and-record file address.

Be sure to set CurRec to 0 before starting sequential file
operations, since DOS Fn 0fH Open FCB does not initialize it.

Notes:   DOS buffers data until a full sector can be written at one time
(or until the file is closed).

See Also: Fn 1aH (set DTA)
Fn 40h (write to handle)
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DOS Fn 15H: Write Sequential File via FCB