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To   : All 1571 owners
From : Ed Parry, Sepulveda, CA
Subj : Extending 1571 DIR entry capacity
Date : 23 April 1987

1) 1st the explanation: I bought C POWER 128 in September of 1986. I
noticed that the disk was actually a FLIPPY. Two single formatted sides
on one disk. The back side contains all the LIBRARY's, the front
contains other C programs and files. I thought it would be nice to fit
these ALL on ONE 1571 formatted disk so I wouldn't have to flip the
disk while linking my LIBRARY's.

2) To the rescue: While on Chris (ARC) Smeets BBS a few days ago I
posted that I was looking for ideas or solutions to this "extended DIR"
prob. I had tried unsuccessfully several weeks before and gave up in
frustration. (8 hours with nothing to show get's depressing!) Chris
himself posted a reply that ended up being the solution to my problems.
Following is the technique I used to make my C POWER 128 disk hold 173
directory entrys. The main idea/technique is HIS idea, I just fine
tuned a bit here and there for the 1571.

3) Limitations : 1st, we both learned that your CANNOT write to an
"extended dir" once you alter the disk to obtain the extended dir. To
get the files on there in the 1st place requires some work. U CAN ADD
further files in this manner but CANNOT add files without playing with
the disk a bit.

4) Here's how to do it:

a) Format a disk in 128/1571 mode. (Gives a disk of 1300+ blocks)
b) copy all the SIDE TWO files to your destination disk.
c) Enter and run this little program:

10 open8,8,8,"$0:*":rem read dir as a SEQ file.
20 open9,8,9,"old dir,s,w":rem open SEQ file to host our "old dir"
30 fori=1to254:get#8,a$:next:rem skip BAM (18/0)
40 get#8,a$:s=st:rem start grabbing DIR bytes/save i/o status
50 print#9,chr$(asc(a$));:rem output byte to OUR "old dir" file.
60 ifs=0 then 40:rem loop until we hit EOF.
70 close8:close9

For 1541's in C64 mode you have to add in a line:

45 ifa$=""thena$=chr$(0):rem haven't tried it yet but oughta work!

What this little program does is READ your current directory as a SEQ
file and then re-writes it into another SEQ file. If you check your DIR
after you run this program you'll see the file "old dir" in there.
It'll be as many blocks long as your DIR is currently using.

5) Now use a good sector editor (I suggest DISKNOSER 128 v2.0!) and go
back thru track 18, starting at sector 1 and change all the "filetype"
bytes to $00's. You'll note these easily because they are the bytes 3
to the left of the 1st letter of the filenames. Generally these are
(REV)a's and (REV)b's. There are 8 entrie's in a DIR sector if the
sector is full. The LAST DIR sector will have a LINK of 000/255. (Or
000/000 if your using NOSER.) Simply link thru the DIR sectors
nullifying all the active filetypes insuring to (re)write the sector
after you've made your alterations.

6) When you get to the "old dir" file entry you should write down the
TRACK/SECTOR link for the start of that file. It is VERY important
since we will eventually LINK our TRACK 18 dir to that TRACK/SECTOR. To
find out the track/sector link for the file put the cursor on the 1st
character of the filename ("o") and cursor LEFT twice. Check your JUMP
link indicator and jot down the track and sector. This will be your
extended DIR!

7) Now we're ready to copy further. Your DIR should now appear empty
yet the BAM will reflect all the blocks used so nothing will get
overwritten. File copy the remainder of your files over to the disk
now. (I used UNICOPY+/128 that has been modified so 1571 side two slow
downs don't occur! (Thanx JG!))

8) When done, reboot your sector editor. Trace thru the NEW DIR files
that will start at 18/1 until you reach the 000/255 (block without a
valid JUMP link). On the 1st TWO bytes of that block, edit the 1st byte
to contain the value of your "old dir" TRACK and the second byte of
that block to the value of your "old dir" SECTOR. (Noser users note
that all EDIT values MUST be 3 digits. IE:3 would be "003". 15 would be
"015" etc. Both DIR are now linked!

9) I ran into a snag. It seems when a 1571 hits ANY sector that is
numbered ZERO ("0") that it think's it has hit the end of your dir.
After I figured this out (took an hour of figuring!) I decided to
simply COPY the TRACK/0 sector to another NON 0 sector. In MY case 24/0
was copied to 24/3. If you have a sector 0 in your "old dir" file
simply find an empty sector near or in the same current track (altho
not essential) and copy the sector 0 block to your NEW block. Then EDIT
the links (1st two bytes of EVERY sector = TRACK/SECTOR link) that
pointed to your sector 0 to point to your NEW track/sector: IE: (In MY
case)

24/14 - pointed to 24/00
24/00 - pooped out my extended DIR when it got here!
24/06 - 24/00 pointed here.

I copied 24/0 to 24/3.
I EDITed the 1st two bytes on 24/14 to point to 24/3.
I was done and it works!

10) Conclusion: As a READ only disk I am quite satisfied. You can add
MORE files long as you disconnect the "old dir" every time you save to
the disk. I also have not attempted to validate for fear that it would
mangle the disk in some way. The only wasted block I am aware of is the
SECTOR 0 block (24/00) that I copied to another sector.

I hope this proves informative and interesting. Much thanx to Chris
Smeets for his ingenious idea.

*QUICK DISKNOSER/128 v2.0 NOTE* - When it became obvious I had to copy
the sector I decided to update/modify DISKNOSER 128 a bit. I added in
COLOR (lost a little screen print speed but it's WELL worth it!), added
in a COPY sector option (Just READ a sector then hit C and enter your
target TRACK and SECTOR!) and modified the DOS wedge and DIR wedge a
bit. For a QUICK dir hit a "$". For patterned DIR's just enter the
pattern at the Disk Command (wedge) prompt. (IE:$*=p for all program
files...) Lemme know whatcha think of DISKNOSER v2.0 and how your DIR
EXTENDING adventures goes!


thanx, Ep

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