Function 15h (21)        Sequential Write, Using FCBs

Writes the record addressed by the current block and current record
fields from the Disk Transfer Address (DTA), then increments the block
and record fields.

On entry:      AH         15h
DX:DS      Pointer to an opened FCB

Returns:       AL         00h       If write was successful
01h       If disk full
02h       IF DTA too small (segment wrap)

Network:       Requires Write access rights


Notes:         The sequential record number is taken from the
values in the current block (offset 0Ch) and the
current record (offset 20h) fields of the FCB. These
fields are automatically updated after the write
operation. The number of bytes to write is taken
from the record size field at offset 0Eh of the FCB.

The data to be written to disk is taken from the
current Disk Transfer Address (DTA). Use Function
1Ah to set the DTA. If the transfer of data would
cause segment wraparound, an error 2 is generated.

If the record written doesn't fill an entire sector,
DOS buffers the data for an eventual write when a
sector's worth of data is accumulated.

If the file specified has the read-only attribute
set, the write is not performed.

See also: 0Fh
See also: 1Ah
See also: 22h
See also: 28h
See also: FCB

15h (21) Sequential Write, Using FCBs