Re: Help with NIB, PO, and DO?

[larva_jt1@yahoo.com (Jeffrey Theusch)]

On Mon, 02 Jul 2001 23:43:24 -0500, Rubywand <rubywand@swbell.net>
wrote:

>Jeffrey Theusch writes ...
>> 
>> I am starting work on an ADT-like program called "ADS", Apple Disk
>> Server.  It involves using a disk image selector interface and
>> transferring the image to a temporary 5 1/4" floppy.  After it is
>> booted, a restart of the Apple would result in transferring the temp
>> floppy back to its original image file on the PC, updating any
>> changes.  Other options would do simple transfers and other ordinary
>> "stuff."
>> 
>> I have most of the operation planned out, but for a few details, I
>> need more information to continue:
>> 
>> 1. A powerful feature of my new application could be the use of a
>> variety of image formats, most notably NIB (You can make transfers of
>> copy-protected disks and also preserve volume numbering!).  From what
>> I now know, NIB is the format containing original disk bytes, right?.
>> Therefore, a fairly simple routine could dump these bytes over a
>> serial line.  But, how do you do this?  Each track must have a
>> starting point and ending point, how do I detect this when the disk is
>> spinning?  What order is the NIB disk image in relation to the
>> physical disk?  And what about half- and quarter-tracks?  How are
>> these managed?  Would a disassembly of Saltine's Super Transcopy help?
>> 
>
>     Looking at SST might help answer some of the above.
>
>
>> 2. I know that .dsk files can possibly be in Prodos Order (.po) or DOS
>> Order.  What are these orders,
>
>     A sector ordering is a translation of the particular DOS's sector
>naming/numbering to hard sector names/numbers. For DOS 3.3, you have ...
>
>DOS 3.3    Hard 
>Sector #   Sector #
>
>  0          0
>  1          D
>  2          B
>  3          9
>  4          7
>  5          5
>  6          3
>  7          1
>  8          E
>  9          C
>  A          A
>  B          8
>  C          6
>  D          4
>  E          2
>  F          F
>
>
> 
>
>    "DOS 3.3 ordering" in a regular 5.25" .dsk or .do disk image would
>arrange the data in the order used by DOS 3.3. Putting this another way, if
>you are running DOS 3.3 you can read the disk image file in 256-byte chunks
>and write it sequentially (starting with Sector 0 on Track 0),
>sector-by-sector and track-by-track.
>
>     Similarly, "ProDOS ordering" places data in a disk image in sequential
>512-byte block order. On a 5.25" disk, the ordering is ...
>
>
>ProDOS          Hard 
>half-Blocks    Sector #
>
>  0a  0           0
>  0b  1           2
>  1a  2           4
>  1b  3           6
>  2a  4           8
>  2b  5           A
>  3a  6           C
>  3c  7           E
>  4a  8           1
>  4b  9           3
>  5a  A           5
>  5b  B           7
>  6a  C           9
>  6b  D           B
>  7a  E           D
>  7b  F           F
>

So if an Apple program wanted to use RWTS of DOS 3.3 to write a .po
image to a physical 5.25 disk, would this be the conversion table? 
(please double-check my work)

.po		DOS 3.3 Sector
Half Block
(256 bytes)

0		0
1		E
2		D
3		C
4		B
5		A
6		9
7		8
8		7
9		6
A		5
B		4
C		3
D		2
E		1
F		F

And, I assume the _tracks_ are in a uniform linear order?

i. e.	0	0
	1	1
	2	2
	...	...

What I will probably do with my application is use a built-in
conversion matrix to convert .po and .do formats on the fly.

>
>
>
>     There is a discussion of suffixes and ordering in the FAQs File Utils
>page at http://home.swbell.net/rubywand/Csa2FLUTILS.html#006 .
>
>
>> and how can I detect the difference in disk image files?
>>
>     Some emulators try to do this for .dsk files (which, technically, can be
>DOS 3.3 or ProDOS order).  Not sure what method they use. Possibly, they
>assume DOS 3.3 order and run the boot code-- if it bombs, they try ProDOS
>order.
>
>     You could check an image for the presence of code normally associated
>with DOS 3.3 or ProDOS or assorted DOS 3.3 variants and see if its location
>in the image corresponds to DOS 3.3 or ProDOS ordering.
>
>     A simpler approach is to stick with current standards. That is, a 5.25"
>disk image name ending with ".po" --> ProDOS ordering. Otherwise, you have
>DOS 3.3 ordering. You could allow the user to override these defaults.
>  
>
>
>> 3. Is there any basic info on the 2mg format that could help me
>> incorporate it into my application?
>>
> ....
>
>     There is a good explanation on A2Central.com  at ...
>
>http://a2central.com/programming/resources/filetypes/ftn-e0.0130.html
>
>The statement: "+$008  Word  The length of this header, in bytes.
>Should be 52" seems to be incorrect. The usual value is 40 00 (header length=
>64 bytes).
>
>

BTW, where is the *best* (1. price, 2. convenience) place to obtain
Beneath Apple DOS and Beneath Apple Prodos?

>Rubywand