ent numbers) and each partition on each disk (if a partition exists) is assigned a number in turn. Virtual disks on the other hand do not have device numbers as they don't physically exist however both require a driver; that is a small program that sits between the disk and NextZXOS and translates each device's individual characteristics into the common set of controls that NextZXOS understands. That alone however is not enough; NextZXOS needs to assign a drive to each partition on a disk (or in the cases of virtual disks and the RAMdisk to the disk itself). As it comes with your System/Next™ distribution; NextZXOS knows three types of physical disks: SD Cards, the RAMdisk and floppy disks and two types of virtual disks: +3 floppy disk images and IDEDOS hard disk images. It also knows virtual and physical tapes both addressable via the reserved drive t:. Physical disk device numbers start at 0 and are assigned according to the table that follows:

Table 15 – Device Number assignments

On an unexpanded ZX Spectrum Next with an unmodified distribution of NextZXOS, the first used number is 4 which is the RAMdisk and the second is 5 as System/Next™ comes on an SD card containing only a single FAT partition. As seen on the table above, device numbers 2 and 3 refer to floppy disk drives (not yet supported by NextZXOS).

Mounting

In order for NextZXOS and NextBASIC to know how to access a partition or disk (be it physical or virtual) this partition/disk has to be mounted. That is the process where a partition on a device gets attached to a drive. If freshly installed, NextZXOS will automatically mount two drives; drives c: and m: the first being device 5 partition 1 (in other words the System/Next™ distribution's SD card plugged into the first SD reader of the system) and the second one being device 4 (the RAMdisk). On an initialised CP/M distribution (as we'll see further below) one more drive will be mounted and that's drive a: (assigned to cpm-a.p3d located inside c:/nextzxos/).

Generally speaking, if there are more than one FAT partitions detected on the SD card(s), they will be automatically mapped to drives c: onwards on startup.

Finally, any files located inside the c:/nextzxos/ directory, are mapped to the appropriate drives (if the drive in question has not already been mapped), if they are named as follows and are valid +3DOS partition images:

DRV-A.P3D
DRV-B.P3D
(…)
DRV-P.P3D
CPM-A.P3D
CPM-B.P3D
(…)
CPM-P.P3D

Virtual images named DRV-x.P3D (where x is a letter from a to p) have preference over virtual images named CPM-x.P3D so in the presence of both, the DRV-x variant will be mounted. Apart from the auto-mounting procedures described above; we can also manually mount partitions and disks. This will be covered a bit further below at its own section.