Further information about drives and CP/M
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CP/M on the ZX Spectrum Next cannot access the standard SD card drive C: (or
other drives you may have due to having additional SD cards inserted, for
example). This is because CP/M directly accesses disks at a low level, and is
incompatible with FAT filesystems.

Therefore, on the Next, CP/M runs from a disk image file. These can either
be .P3D files (created by the .MKDATA dot command) or .DSK files (images of
standard ZX Spectrum +3 disks).

Initially, your SD card is supplied with a single image:

        C:/NEXTZXOS/CPMBASE.P3D

When you first start CP/M, this is automatically renamed to:

        C:/NEXTZXOS/CPM-A.P3D

You can access multiple disk images at once in CP/M. To do this, simply
create additional files with .MKDATA using the same naming scheme.

eg. at the NextZXOS command line, type the following:

        .mkdata "/nextzxos/cpm-b.p3d"
        .mkdata "/nextzxos/cpm-e.p3d"

When you next use CP/M, you will have drives A: B: and E: available.

Note that you can have a drive C: in CP/M if you wish, but this is not the
same as the C: drive used in NextZXOS.

Up to 15 drive images can be used at once by CP/M, and they can be mapped to
any drive A to P, simply by naming the files in any of these ways:

        c:/nextzxos/cpm-X.p3d
        c:/nextzxos/drv-X.p3d
        c:/nextzxos/cpm-X.dsk
        c:/nextzxos/drv-X.dsk

(where 'X' is the drive letter, from A to P). If you have created multiple
files referring to the same drive letter, CP/M will use the ones named
"CPM-X" in preference to the ones named "DRV-X". It has no preference over
.P3D or .DSK, so if there is a CPM-B.P3D and a CPM-B.DSK, then the first one
in the directory will be used.

Note that NextZXOS will also automatically mount these drive images when it
starts up. You can view them in the Browser (press D to change drives) and
copy files between them etc. NextZXOS will mount "DRV-X" files in preference
to "CPM-X" files. You can also manually mount other disk images which
don't follow the automatically-mounted naming scheme. To do this, just press
ENTER on the .P3D or .DSK file in the Browser.
