Re: DOS 3.3 Nibble Encoding

[pingn@malibu.sfu.ca (Albert Ng)]

sbdocker@acs.ucalgary.ca (Sean Brendan Dockery) writes:

>It is not explicitly stated in the Beneath Apple DOS manual as to how
>the boot sector is encoded.  For the same drives to boot both 13
>sectors/track DOS 3.2.1 disks and 16 sectors/track DOS 3.3 disks, it
>seems rather unclear as to what encoding scheme would be present in
>the firmware to overcome.  Can the Apple IIc and Apple IIGS internal
>firmwares even handle booting DOS 3.2.1 disks directly?

Well, are you refer to some dual boot disk ?
If so than a custom Dos 3.3 Track 0 Sector 0 is created and it's almost
like the image of Dos 3.2 Boot Rom.   

So the Dos 3.2 , Track 0 Sector 0 is loaded  and proceed as usual.

One thing that puzzled me is, how can I differentiate from a Dos 3.2 sector 0
or a Dos 3.3 sector 0 ?? 

Remember Dos 3.2 's address mark is D5AAB5, while 3.3 is D5AA96 . That's how
things works. 

I learn all this by examine some Sirius game disk, FYI.

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     / ..\   Regards, albert.
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