Rookie drive NX

Rookie drive NX contains two drivers in the same ROM

  • Rookie drive 720 driver -> Floppy disk emulation based on MSXDOS 1.0 (ideal for MSX1 computers)
  • Rookie drive Nextor driver -> With Nextor operating system (needs minimum 128K, usually for MSX2)


Boot loader

At the start, Rookie drive automatically starts a code that will detect the type of MSX we have, if it detects MSX1 will launch the ROM of Rookie drive 720 (Floppy disk drive emulatotion), if it detects MSX2 will release the version with Nextor.

At boot time we can “force” the loading of the diskette emulation version by pressing “7 or D in the newer versions”  (720kb) or the Nextor version by pressing “N”.

Rookie drive Nextor driver v1.0

This driver is for Nextor o.s.  “Nextor is a disk operating system for MSX computers. It is actually an enhanced version of MSX-DOS, with which it is 100% compatible, and it identifies itself as MSX-DOS 2.31 to MSX-DOS aware applications.” 

Nextor requires 128k of RAM to run.!

A 320K DiskROM is also included in this driver, you can use this DiskROM to boot Nextor and a Filemanager like Multimente or SofaRun.

More info about Nextor in Konamiman’s website:

Very important, Nextor supports FAT12 and FAT16, so if you try to use a device in FAT32 will not work, (if you use SofaRun in the diskROM, then causes a black screen lock), if you stay blocked on the screen in black, reboot The MSX, when NEXTOR.SYS appears on the screen press CTRL + STOP, the message “Terminate batch file (Y / N)?” Appears, you give “Y”, then you can call “BASIC” _fdisk, which will allow you to erase the partitions of the pendrive and create new ones in FAT16 (caution with this option, erase everything!).



Rookie drive 720 v1.3.1 (Floppy disk emulation)

Rookie drive 720 supports only one virtual disk at a time. The use of several simultaneous disk images is not implemented yet.

Here is the summary of rookie drive 720 features:


Listing of USB root directory

Using the command:

call usbfiles

We will get the list of files contained in the root directory of the USB device, this will allow us to see the image files contained in the USB device and then load them using the insertdisk command.

Change current folder

With this command we can change the active folder inside the USB device:

Call usbcd ("directory")

You can return to the previous folder using:

Call usbcd ("..")

This feature has been available since version 1.3.5


Load Rom files of 8/16/32K

Load a .ROM file to the ram and start executing

call loadrom("filename.rom")

(The file must be located in the root directory of the USB device, and filename must be in 8.3 format)

Insert disk

Simulates the “insertion” of a new disk, through this instruction the disk image to be used is specified. Disk images of up to 720 kbytes are currently supported.

The format of the call command is as follows:

call insertdisk("imagename.dsk")

(The file must be located in the root directory of the USB device, and filename must be in 8.3 format)

If the command is executed correctly we can access the list of files using the “files” command, and work normally using typical commands, such as: run, save, bload, etc …

To create a disk image from the PC we can use Disk-Manager, this program is very practical when creating new DSK and adding files. (

Automatic reinsertion of the last disc used

After the restart, the last disk image that was used will be automatically inserted again, this action can be canceled momentarily by pressing the ESC key during hardware initialization. The internal operation contemplates the creation of the file USBMSX.INI, in which the name of the image to be loaded is saved, so that it is persistent both to reset and to shutdown the machine.

Creating a new image

This command is in the experimental phase, since you need to execute internally the format command, which has not been fully developed. Currently, if we execute this command we will get a disk image of 720kbytes full of 0xff characters.

To create a new image just launch this command:

call createdisk("filename.dsk")
System Restart

With the command:

call reboot

We will be able to restart the machine without a reset button, or to cut off the power. This command is useful when you insert a disk image that needs to be started directly to run, or when the image contains an MSX-DOS disk and the “call system” command does not work.


Format the virtual disk that is inserted.

call format