The RAM in your interface can be used to store alternative versions of BASIC, or Interface 2 ROM images. Once they have been added, you can start them up at any time using a simple command.
Additionally, ResiDOS can be enhanced by loading optional packages which provide additional features such as new commands and access to other types of filesystems, such as the common FAT-16 type used on PCs. The currently-available packages can be found here.
You can install ROMs in one of two ways:
Suitable ROMs for installation include ResiDOS- specific packages, alternative BASICs (such as Gosh Wonderful, SE BASIC or Sea Change) or Interface 2 ROMs (such as those originally released by Sinclair, or unreleased prototypes from Parker which have recently come to light).
If you have copied a ROM to disk or card, then install it with the following commands:
The first command reserves space for the installation process, and the second performs the installation. The name of the ROM kept by ResiDOS will be the filename (excluding any extension after a "."). The number, n, should be any of the following values, added together as appropriate:
If you don't specify a value, then the default of 0 will be used. If you are installing a package, then any value except 0 will be ignored, since packages include their own information telling ResiDOS how they should be installed.
Note that it is generally advisable to only store BASIC ROMs into the non-writeable "ROM" part of the memory, since unless they have been specifically patched they tend to overwrite themselves. However, if you are running short of ROM space on a ZXATASP interface, you may specify RAM instead. This is not a concern on other interfaces, since the memory can be configured automatically by ResiDOS to be ROM or RAM as required.
A couple of examples are:
An alternative installation method is to load the ROM image into memory, and then install it directly from there. Since this allows you to load from tape, it is handy for installing packages like FATfs when you don't have access to the disk.
To use this method, first CLEAR to a suitable address, and then load in the ROM to above this address. For example:
Then the ROM can be installed by using the following form of the %INSTALL command:
As before, the "n" value is optional.
To install the package just loaded in the previous example, use:
You can see a list of all the installed ROMs in your interface by using the following commands (the second version includes hidden ROMs, used by the system but not selectable by the user):
You can uninstall any ROM using the following command (this only removes it from the interface memory, not from the hard disk):
Once you have installed some ROMs as described in the previous sections, they are available for instant use whenever you switch on the Spectrum. To use the features of an installed package, see the documentation for that package. To switch to an alternative BASIC, or run an Interface 2 ROM, use the following command:
For example, having installed the ROMs above, we could use either of them like this:
If you specify an Interface 2 ROM, it will immediately start. Pressing the reset button will reset the ROM. To return to ResiDOS you will need to either reset your interface and the Spectrum together, or switch off the power completely and then switch the system back on.
If you are activating a BASIC ROM, the Spectrum will restart using that BASIC. You can then use ResiDOS commands as normal, and the additional features of the particular BASIC you have chosen.
The new BASIC will remain as the default one even if you switch off the Spectrum and turn back on again. To return to the original BASIC, you can simply select the "Standard" ROM (which is automatically created as part of the installation process), for example:
Alternatively, hold down the CAPS SHIFT key while the Speccy is booting up, and the standard ROM will be automatically re-selected.
One final feature is the ability to switch off the interface memory altogether and use your Spectrum's built-in ROM, without having to unplug the interface or set the upload or disable jumper (this is useful for 128K Spectrums and +3s). To do this, use the command:
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