Appending Data To An Iso Set - Philips CDD522 Operating Instructions Manual

FIG.13 Disjunct ISO 9660 sets in multiple sessions
In Figure 11, the recorded ISO sets remained Disjunct: the |SO
set in session 2 does not refer to any member of the set in
session 1. Disjunct ISO sets need to be selected. To do so, one
needs a selector. On MS-DOS, you may want to type "E\\"", "F:\"
and so on, the same way you select partitions on Hard Disks.
Currently, this is not possible with MSCDEX. In the mean time, a
separate selector is to be supplied which interacts with the
Device Driver, both on the writing (orange) system as on
receiving systems (possibly Yellow-Book readers)..
Selectors make sense for multi-session ISO sets too. Suppose
we had written a directory tree in a first session, as in Figure 12
on page 44. In the next session, we want to update one of the
files in directory A. Since we have a write-once medium, we
cannot erase files. What we can do however, is to copy the ISO
structure (PVD, PT, RD and DF's) from session 1 to session 2,
with a slight modification: now DIR A contains a reference to the
new data file Session 2. Now the path to the original data is lost.
To the user, the data file appears to be updated. However, you
can select session 1 with the selector. After this, the original data
will reappear inspecting the contents of directory A.
APPENDING DATA TO AN ISO SET
One way to append data to a disk is session by session, as
discussed above. However, sessions serve another purpose:
they are ment to make the disk "Yellow", i.e. write Leadin and
Leadout, cfr Physical Structure on page 11, thus writing the TOC
for this session. This action is referred to as "finalizing". By
finalizing, the CD-R disc becomes readable on standard CDROM
readers. Following the orange book, finalizing takes a couple of
minutes for the leadout and leadin (20 MByte!) to be written.