The vortex tool lets you access 720 KB CP/M disk images (Vortex VDOS format on double-density, DD, disks) as used by Schneider / Amstrad CPC home computers with an external floppy drive (Vortex F1-X, either the 5.25" or the 3.5" version). Note that no other CP/M formats are supported though it should be possible to quickly modify the code so that other formats could work as well.
Note: This tool is not compatible with the DSK format used by some CPC emulators (e.g. cpcemu) which stores headers for the disk, each sector and each track. vortex only works with raw disk images (as created by the Linux tool dd).
You can call the vortex tool with either an ls command option or a dump command option, followed by the names(s) of one or more floppy disk image files. The ls command will display information about the files stored on that disk image, such as follows:
[esser@macbookpro:~]$ vortex ls cpc-004.img
Directory listing for 'cpc-004.img'
Us Name RS #E Size [E] 4K Blocks
-------------------------------------------------------------------------------
00 copytool.com -- (0) 3840 [0] 1
00 files-0.bin -s (1) 128 [0] 3 4 5 6 [1] 7
00 files-01.bin -s (1) 128 [0] 8 9 10 11 [1] 12
00 files-1.bin -s (2) 9728 [0] 13 14 15 16 [1] 17 18 19 20 [2] 21 22 23
00 files-2.bin -s (2) 9472 [0] 24 25 26 27 [1] 28 29 30 31 [2] 32 33 34
00 files-3.bin -s (2) 5888 [0] 35 36 37 38 [1] 39 40 41 42 [2] 43 44
00 ts-prog.com -- (0) 8704 [0] 45 46 47
00 ts-prog.dat -s (3) 16384 [0] 48 49 50 51 [1] 52 53 54 55 [2] 56 57 58 59 [3] 60 61 62 63
+ (7) 14336 [4] 64 65 66 67 [5] 68 69 70 71 [6] 72 73 74 75 [7] 76 77 78 79
+ total: 30720
00 zprog.bas -- (0) 7040 [0] 80 81
00 zprog.prg -s (2) 4224 [0] 82 83 84 85 [1] 86 87 88 89 [2] 90 91
00 zprog.scr -s (0) 14336 [0] 92 93 94 95
...
When using the dump command option, the tool will create a new subdirectory (named whatever.d/ if the image file was called whatever) and copy all files from the CP/M image to that directory:
[esser@macbookpro:~]$ vortex dump cpc-004.img
...
[esser@macbookpro:~]$ ls -l cpc-004.img.d/
-rw-r--r-- 1 esser staff 3840 25 Jan 06:37 copytool.com
-rw-r--r-- 1 esser staff 128 25 Jan 06:37 files-0.bin
-rw-r--r-- 1 esser staff 128 25 Jan 06:37 files-01.bin
-rw-r--r-- 1 esser staff 9728 25 Jan 06:37 files-1.bin
-rw-r--r-- 1 esser staff 9472 25 Jan 06:37 files-2.bin
-rw-r--r-- 1 esser staff 5888 25 Jan 06:37 files-3.bin
-rw-r--r-- 1 esser staff 8704 25 Jan 06:37 ts-prog.com
-rw-r--r-- 1 esser staff 30720 25 Jan 06:37 ts-prog.dat
-rw-r--r-- 1 esser staff 7040 25 Jan 06:37 zprog.bas
-rw-r--r-- 1 esser staff 4224 25 Jan 06:37 zprog.prg
-rw-r--r-- 1 esser staff 14336 25 Jan 06:37 zprog.scr
...
Note that file sizes of the extracted files are always multiples of 128 -- this cannot be helped, since CP/M 2.2 does not store exact filesize on the disk. Each CP/M (or AMSDOS/VDOS) application used their own way to signal end-of-file, e.g. via an ^Z or 0xE5 marker or by adding some kind of header information in the file. Use the included cpctxtcnv tool on text files in order to strip the trailing bytes. (Do not use it on binary files as this is likely to corrupt the file.)
cpctxtcnv converts the character set {|}[\]~ to äöüÄÖÜß (UTF-8-encoded). CPC users had to decide whether to use German umlauts (and suffer loss of the brackets, backslash and tilde) or keep those characters (which are needed for programming) and work without umlauts. This was in part because the upper 128 characters of the CPC's character set were line drawing characters. English users of the tool should use the -n option so that this translation step is omitted; in that case the tool will only search for the 0x1a marker and truncate the text file.
If you have physical media, the easiest approach is to use an old computer that still supports 5.25" drives (in BIOS settings you will find the drive type "5.25 inch, 1200 KByte"). Install an old Linux system on that computer's hard disk; I used a Linux system with kernel 2.x, the main point was that /dev is not a virtual filesystem but a regular directory filled with hundreds of device files. If so, there should be two files /dev/fd0h720 (for the A: drive) and /dev/fd1h720 (the B: drive). Using these filenames guarantees that the floppy disks are read in the proper way (as double-density, DD, disks -- not SD or HD). Modern Linux systems will only provide the generic /dev/fd0 and /dev/fd1 which might or might not work.
For reading, dd or ddrescue work fine. I used dd:
dd if=/dev/fd0h720 of=cpc-0xx.img
and transfered the files to a different machine where I used the vortex tool to extract the files.