# Virtual drives

## Contents

- Overview
- Drive emulation by configuration file setting
- Drive emulation by command-line option
- Drive emulation by environment variables

## Overview

As described in Files and locations , the EPOC drives `z:` and `c:` are mapped by the Emulator onto some default locations in the PC file system. This topic describes how you can change these default locations, and how you can add further virtual drives — for example, to simulate a CF card acting as a removable drive.

There are a number of ways of performing these tasks. The recommended method is to use the configuration file. If required, you can also override the location of the emulated `c:` drive using the command-line. Finally, an environment variable method was provided for ER3, and is now deprecated.

Note that any mapping for the `z:` drive must specify a directory named `z`.

## Drive emulation by configuration file setting

The location of virtual drives can be specified by entries in the Emulator configuration file (usually `epoc.ini`). You can override the default locations of `z:` and `c:` drives, or specify additional drives.

An entry should have the form:

  `_EPOC_DRIVE_`<drive-letter> <location>

For example, you could specify an additional `d:` virtual drive using the setting:

        _EPOC_DRIVE_D A:\

which would allow the Emulator to treat your PC’s diskette drive as its own removable drive, which is usually mapped to `d:` on target machines.

## Drive emulation by command-line option

Command line options can be used to specify the location of the emulated `c:` drive. A location set in this way overrides the default settings and any `_EPOC_DRIVE_C` setting in the environment or in the configuration file.

Command | Description
`-C`<emulated C drive> | The argument specifies the path of the directory that should be used for the emulated `c:` drive.
`-T` | Specifies that the system temporary path should be used as the emulated `c:` drive.

For example,

        epoc -Cd:\test\ --

maps the virtual `c:` drive to the path to `d:\test\`.

## Drive emulation by environment variables

In addition to the drive emulation methods previously described, you can also specify virtual drives using environment variables. This is for backward compatibility with ER3: you should now use the `epoc.ini` method.

The environment variable setting has the form:

  `_EPOC_DRIVE_`<drive-letter>

For example,

        set _EPOC_DRIVE_P=c:\test\

sets a virtual drive `p:`, with the real location `c:\test\`.