67 lines
2.7 KiB
Plaintext
67 lines
2.7 KiB
Plaintext
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Path: news1.icaen!news.uiowa.edu!news1.chicago.iagnet.net!iagnet.net!howland.erols.net!newsfeed.internetmci.com!193.174.75.126!news-was.dfn.de!news-fra1.dfn.de!news-ge.switch.ch!news-zh.switch.ch!elna.ethz.ch!not-for-mail
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From: GUDATH@EZINFO.VMSMAIL.ETHZ.CH (Henrik 'Ratte' Gudat)
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Newsgroups: comp.emulators.apple2
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Subject: Re: Disk Image formats
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Date: 2 Dec 1997 07:25:20 GMT
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Organization: F.E.Systems Emulation Technologies
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Lines: 52
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Distribution: world
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Message-ID: <660d50$8tj$1@elna.ethz.ch>
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References: <19971201040901.XAA19285@ladder02.news.aol.com> <34831774.6730572@news.bconnex.net>
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NNTP-Posting-Host: ezinfo.ethz.ch
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X-News-Reader: VMS NEWS 1.24
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In-Reply-To: CUTjefbla@bconnex.net's message of Mon, 01 Dec 1997 20:27:03 GMT
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Hi guys,
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2img is a public format, so here it is : :-)
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Please note that subtype 2 (raw nibbles) has not been further discussed and is
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undefined as of this writing.
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typedef struct {
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char magic[4]; /* "2IMG" */
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char creator[4]; /* Creator signature */
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word16 header_len; /* Length of header in bytes k */
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word16 version; /* Image version */
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word32 image_format; /* Image data format (see below) */
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word32 flags; /* Format flags (see below) */
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word32 num_blocks; /* Number of 512-byte blocks in this image */
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word32 data_offset; /* File offset to start of data */
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word32 data_len; /* Length of data in bytes */
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word32 cmnt_offset; /* File offset to start of comment */
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word32 cmnt_len; /* Length of comment in bytes */
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word32 creator_offset; /* File offset to start of creator data */
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word32 creator_len; /* Length of creator data in bytes */
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word32 spare[4]; /* Spare words (pads header to 64 bytes) */
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} image_header;
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Format numbers:
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0 = DOS 3.3-order dump of disk data. This is really only valid for
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a floppy disk image.
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1 = ProDOS-order dump of the disk data. This is the only valid format
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for a hard disk image.
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2 = Raw dump of the disk nibbles. This is only valid for a floppy disk
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image.
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Flags:
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0x80000000 = Image is write protected (1 = yes, 0 = no)
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Now regarding .po and .do files: these files contain chunks of 256 bytes - the
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logical disk data. Important: the sectors (256 bytes) are arranged in DOS (.po)
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or ProDOS (.po) order. Both OSes have a very specific sector interleaf. This
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means, the disk images contain the sectors in the order as they appear under
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the drive head. So, sector 0 ius the first one but sector 1 is likely to be
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anywhere but the following sector. The interleaf is different fro ProDOS and
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DOS and described in DOS/ProDOS books.
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I hope this helps. You can mail me if it's not clear, or post here.
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- henrik
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