Re: Tips for making Twiggy images

Hello Natalia,

Thanks for the MDDF (Media Descriptor Data File) information for this Lisa Pascal v1 disk. I am very impressed with what you've learned about the Lisa file system structure.

One suggestion that could make your Disk Image Chef a little better is to show dates in format YYYY-MM-DD instead of in DD-MM-YYYY format. For example, September 12, 1983 would appear as 1983-09-12 instead of 12/09/1983 which is confusing for us who are used to dates in USA format MM/DD/YYYY.

Your comment about the Twiggy tag being 24 bytes is interesting, at least the MDDF is reporting this as such.

• David Craig

===

On February 16, 2015, at 1:38 AM, Natalia Portillo wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA256
>
> Hi Tom,
>
> I can tell you that the MDDF seems correct:
>
> claunia_at_zeus ~ $ mono
> /Development/DiscImageChef/DiscImageChef/bin/Debug/DiscImageChef.exe
> analyze -i ~/Downloads/PascalWorkshop1.0_3of3_682-0051-B.dc42
> The Disc Image Chef 2.2.5365.5370
> Copyright © 2011-2014 Natalia Portillo
>
> Image format identified by Apple DiskCopy 4.2.
> Identified by Apple Lisa File System.
> LisaFS v1
> Volume name: "Pascal.3"
> Volume password: ""
> Volume ID: 0x9B8C4DD721000180
> Backup volume ID: 0x0000000000000000
> Master copy ID: 0x00000000
> Volume is number 0 of 0
> Serial number of Lisa computer that created this volume: 384
> Serial number of Lisa computer that can use this volume's software 384
> Volume created on 12/09/1983 10:47:05
> Some timestamp, says 01/01/1901 0:00:00
> Volume backed up on 01/01/1901 0:00:00
> Volume scavenged on 01/01/1901 0:00:00
> MDDF is in block 41
> 1683 blocks minus one
> 1642 blocks minus one minus MDDF offset
> 1684 blocks in volume
> 536 bytes per sector (uncooked)
> 512 bytes per sector
> 1 blocks per cluster
> 1643 blocks in filesystem
> 27 files in volume
> 925 blocks free
> 128 bytes in LisaInfo
> Filesystem overhead: 25
> Scanvenger result code: 0x00000000
> Boot code: 0x00000000
> Boot environment: 0x00000000
> Overmount stamp: 0x0000000000000000
> Volume is clean
>
> About the tag size, as you can see the MDDF clearly says there should
> be 536-512 bytes (that's, 24 bytes in a twiggy tag). In Sonys, it says
> 20 bytes.
>
> But you should think about one thing, that is, how much can you read
> talking to the floppy controller, and how much it is really stored in
> the disk. We'll need something like DiscFerret to really know.
>
> Really why haven't someone yet taken a cheap ARM Msomething and made
> one that works in a simple development board, like, say, TI LaunchPad
> I don't know.
>
> Anyway, you got a sep83 disk :p Cheers!
>
> My tool can also compare sector by sector and tag by tag of any DC42
> image.
>
> Free, opensource, http://github.com/claunia/DiscImageChef feel free to
> use it and bomb me with suggestions.
>
> Someday in 2015, if destiny allows, I'll implement reading LisaFS, as
> I have already decoded it an I'm able to do without using the tags to
> find the files.
>
> Regards,
> Natalia Portillo

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