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HDCPM

1,557 bytes added, 13:51, 1 August 2022
** [[Symbiface II]]*
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** [[uIDE-16]]* (base address = &FEF0)
** [[M4 board]]*
** [[USIfAC II]]*
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====CP/M Plus disk image files====
A CP/M Plus disk image file is a raw binary image of a CP/M hard disk or partition. Its name must be in the form CPMDSK0x.IMG where x=1, 2, 3 or 4 in order to be recognized by HDCPM. The size of the file depends on the Disk Parameter Block of the virtual hard disk it represents and for the initial release of HDCPM it is fixed and equal to 1 reserved track * 256 sectors per track * 512 bytes per sector + 8MB data = 8519680 bytes. If possible create your CPMDSK01.IMG file in a modern computer and copy it in the root directory of your FAT formatted medium. You can use the free online hex editor hexed.it or any hex editor capable of creating binary files filled with a specific pattern.<br />In case of hexed.it select 'New file' fill in 'Size of the new file = 8519680' and 'Fill Pattern = 0xE5' and press apply. Save the file as CPMDSK01.IMG If you have a FAT capable DOS installed in your AMSTRAD you can use the provided MAKEIMG.BAS utility to create your image file. Keep in mind that it takes more than 1.5 hour for a 8MB image file to be created that way.<br />CP/M disk image files can be accessed by a modern computer with cpmtools*. Use the command |HDDEF to see the record you must insert in the diskdefs file.<br />
The HDCPM record for diskdefs is:
 
diskdef hdcpm
seclen 512
tracks 65
sectrk 256
blocksize 8192
maxdir 1024
skew 0
boottrk 1
os 3
end
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HDCPM is not FAT aware. It utilizes code to search in the root directory of a FAT formatted medium in order to find the CP/M image files. Then it finds the LBA of the first sector of each file and passes it to the CP/M hard disk driver. The CP/M hard disk driver doesn't know anything about FAT or image files. It accesses the image file as if it was a real hard disk. It works on the sector level with LBA addressing so it expects the 'hard disk' to be a continuous block of sectors.<br />
A CP/M image file can easily become fragmented during its creation, especially if the hard disk is nearly full. I advice you to create/copy your CP/M image files to your FAT formatted hard disk/partition while it is still empty. HDCPM will never fragment a CP/M image file.<br />
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====CP/M Plus disk/partitions====
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