Radio Shack TRS-80 Model II Reference Manual page 222

Model II TRSDOS
DIRWR
Direct Write (function code 44)
This routine writes the specified record. It writes your record into the
specified record position of the file.
Note: For
VLR
files, you can only position to the beginning or end of file.
When you write to a
VLR
file, the end of file is reset to the last record written.
Entry Conditions
(DE) = Data Control Block for currently Open file
BC
=
Record number you want to write
BC = 0 means write first record in file
BC
=
X'FFFF'
means write record at end of file
(HL)
=
A=
Reserved for use in later versions of
TRSDOS
44
Before calling
DIRWR,
put your record into the Record Area pointed to by
RECADR
in the Parameter list, or, if
RL=256
and record type is Fixed, put
record in area pointed to by
BUFADR.
Exit Conditions
NZ
=
Error
A
=
Error Code
258