### Working With Program Paks

By default trs80gp starts up with a Multi-Pak enabled which allows up to 4 program Paks to be inserted. Real Program Paks are usually cartridges although they can also be ROMs with internal devices such as a floppy controller. The Multi-Pak labels each of the 4 slots as 1, 2, 3, 4.

The `-pak file` command works similar to how disk images are handled. The specified file is loaded as a (self-booting) ROM into the first free Multi-Pak slot. Use `-pakN` to specify a particular slot for the Pak. Adding a "q" to the option disables the normal auto-boot of the Pak. A file ending with `.ccc` is automatically interpreted as a `-pak` command.

trs80gp supports two special Pak devices, the standard `:fdc` Tandy floppy controller and `:hdc` hard driver controller. These do not have to be specified explicitly on the command line. If slots 3 and 4 are empty, trs80gp will automatically insert the HDC into slot 3 and the FDC into slot 4 (and set the switch position to 4 if not already specified). The FDC is automatically given a ROM image matching the version of Disk Extended BASIC in use. The `-pakdev :fdc filename` command can be used to override the ROM inside the FDC hardware. This is useful for certain alternate DOSes.

Although, in theory, multiple FDC and HDC devices could be added to a Colour Computer, trs80gp only allows one of each although it can be in any slot. The limitation is largely the result of the difficultly of having the UI handle up to 16 active floppies or hard disks attached to 4 different controllers.

At startup, the program pack select switch will be set either to the FDC device slot (if any) or to the first slot if it is not empty. The switch setting can be explictly set on the command line with the `-pakswitch N` command. The Multi-Pak can be completely disabled using the `-pakx` command line option.

If the `-dx` and/or `-hx` command line options are used it is no longer allowed to insert `:fdc` and/or `:hdc` devices. This is because the `Disk` and/or `Hard Drive` menus will be removed and it isn't possible to insert or attach new drive images.

#### The Pak Menu

Unlike a real Colour Computer, the slots of the Multi-Pak can be manipulated while the machine is running. The `Pak` menu allows you to choose new ROMs or even devices to load or even remove/insert the Multi-Pak itself.

Several operations in the menu will force a cold restart of the emulated machine and are marked as such with the text `Reboot...` at the end of each selection. Moving cartridges around changes the memory map and (as such) the emulated 6809 would typically get stuck executing nonsense code.

The menu shows the device/Pak in each slot, showing `<empty>` if the slot is not used. A checkmark by the slot indicates the switch is set to that slot. The Multi-Pak hardware can change active devices independent of the switch which means the other unchecked Paks may be in use.

The submenu for each slot can change the switch position to that slot (and reboot) or insert a new Program Pak or device. Since only one FDC or HDC is allowed by trs80gp, choosing to insert one when one is already present in another slot will prompt you to move the cartridge.

The `Autostart` is equivalent to the `-pakq` command. If autostart is disabled, the ROM Pak will not automatically start on cold boot, even if the switch is positioned to it. In technical terms the `CART*` signal is not generated.