Technical Information
If
a
source
or destination MO error occurs during
HDCOPY4,
the
record
in
which
the
error occurred is nol copied
.
HtJUWY* marks
i as noncopied m ihe header record
of
the
destination
diskette
and tho copy may bo continKod,
An experienced programmer can
reconstruct this
data
The
infor-
mation below gives the layout of the
header record
thai
should
be
used
for this purpose.
This information should be sufficient for an
ttxpgrienued
pruyrairuntJi.
Header Block
The
first
record
of every
destination disk contains a block
of
infor-
mation
arranged
as
describee below:
Description
disk
number
in the copy set
filename/ext
time and dale of
copy,
BASIC TIMES format
ending record
number (original source File)
first
source-
reeurd (destination diskette)
fas: source record
(destination diskette)
end
of
file
offset
[original
source
file)
ASCII
representation
of
a
random number
Logical Record Length (source file)
currently unused
defective source file record
numbers
1
These
fields are stored
as compressed integers with
trie BASIC MKIS function.
Description
If any
records are
bad, TR$DQS
stores
their numbers as integers
(2-byte
fields) Starting
at Syte
1£9
in
the
header
block.
The
cor-
responding record
of
the destination
file ia marked
with the
message HDCOPY^BAD
SECTOR.
To locate the bad record, determine the offset
into
the
file
by sub-
tracting
the
starting record
number
(fifth field) from
the
bad
record
number
Add
1
because
the
tirst
record
always
contains
the header
information. For example, if Record
i4ffl
is
bad,
and the diskette
contains
tho block
of
Records
1OT
lo
300, tho
bad
record is
the
41sl
record
in the file:
Hfi
-
1W
=
4*
1-
1 (header)
-
41
st record
Bytes
1
-
2
3-
14
15
•31
32 33
34 35
36
-37
38 39
4<J
45
46
47
4B
I2A
129
256
3C
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