Moin Kollegen,
ich tüftle hier mit dem Programm "22Disk" rum, und versuche,
eine Config für die ITT Disketten zu schreiben.
Die letzte Einstellung, die mir noch völlig schleierhaft ist,
bezieht sich auf die u.a. "Schalter" AL0 und AL1.
Hier ein Auszug der Beschreibung, welche dem Programm
als DOC File beiliegt...
AL0 and AL1 form a bit mask, beginning with the most significant bit in byte AL0
and ending with the least significant bit in AL1. These two bytes map the first 16
allocation blocks of the disk.
A 1 bit in a position indicates that an allocation block is reserved, usually for
the directory (see DRM, above).
4. Examine the first directory entry. The second 16 bytes
(the second line of the entry) gives a list of alloca-
tion unit numbers belonging to the file. The first one
of these will tell how many allocation units have been
reserved to hold the directory. Thus, if the first al-
location byte is 04, four allocation units have been al-
located to the directory. Another thing to note is
whether the allocation unit number appears to be an
8 bit or 16 bit quantity. For example, if an entry has
the following form:
00 50 49 50 20 20 20 20 20 43 4F 4D 00 00 00 10 .PIP COM....
04 00 05 00 06 00 00 00 00 00 00 00 00 00 00 00 ................
the allocation unit designators are 4, 5 and 6 and are
16-bit quantities. On the other hand, the following item:
00 50 49 50 20 20 20 20 20 43 4F 4D 00 00 00 10 .PIP COM....
04 05 06 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
shows the same allocation units, but as 8-bit quantities.
If 16-bit quantities are involved, more than 255allocation
units are defined for the diskette, if an 8-bit quantity,
less than 256 units. This serves as a check for later com-
putations. In any case, the first allocation number of the
first directory entry gives the number of bits to be set in
AL0 and AL1. Thus, for an allocation number of 04:
AL0 11110000B Al1 0 ????HÄ????
Was muss ich denn angeben, wenn meine Bytes so aussehen:
02 00 04 00 06 00 00 ....
Was hat (im Beispiel) 04 denn mit 11110000 zu tun?
(das "B" steht für Binär)
Hat jemand einen Tip???
Stefan
