Re: firmware for the PseudoDisk

["Alex Freed" <alexf@mirrow.com>]

> > 2. Use FAT16 on SD/MMC to store files: .nib images and .hdv images.
> > Treat them as nibble images and ProDOS volumes depending on
> > extension. On boot load a program that will list the FAT catalog
> > and allow selecting an image by name.
>
> That's a much better idea as any platform can manage FAT16 disks.

Yes, that's the idea.

> You could limit the search to a predefined folder, for example a folder
> called "Apple2", in the same way that the digital cameras do it.
> Then we could group our (lots of) images in folders. To activate a
> given set it would be as easy as renaming the proper folder to
> "Apple2".

I don't like this last part. Activating by using an external computer and
renaming - not very elegant.

What I want is some code loaded into Apple at boot time that will
parse the SD card's directory and allow the user to select a
file - ProDOS volume or a NIB image. Reading raw sectors from
the SD card is trivial via the ProDOS interface. Somebody needs to
write an Apple application to do it.

I'm sure there are many people on this list more qualified than me.
So I'll probably write a very simple one and let somebody else
improve on it.

> Also, please try to avoid the need for defragmenting. This is a call
> for disaster ! The files tend "naturally" to be fragmented. I'm not
> sure when you said in another post :
>
> > It's relatively easy and fast to map ProDOS image's ralitive sectors
> > to phisical sectors on the SD card. For nibble mode we only need
> > a list of pointers to 13 blocks that represent a "track". "
>
> Do you mean "It's relatively easy to read fragmented files" ?

Yes, it is. Consider the NIB image. At any given time before the "head"
repositioning (that takes a while on the real hardware) we are only
reading a single track. That is 13 blocks. Even if a cluster is one sector,
we only need to store POINTERS to the 13 physical SD card blocks
that hold this data. They don't need to be contiguous.

>
> Regards,
> Jorge Chamorro
>
-Alex.