Sunday, 15 September 2019

Changing the drive number of the internal drives

A number of people have asked in the past how to change the drive numbers of the C65's internal 3.5" drive.  By default it sits on both device 8 and 9 (for the optional 2nd 3.5" drive via the little round PS/2 style plug on the C65).  Until now, I didn't know.  But Falk who is working on GEOS for the MEGA65 figured it out:

You just have to set the contents of $10113 and $10114 to the device numbers.  Note that these are 20-bit C65-style addresses, so you have to do some jiggery-pokery to swap them if you are in C64 mode on a C65, since there is no 20-bit monitor in C64 mode.

You can work around this by using the OPEN command to command the device number changes, e.g.:

However, if you are on a MEGA65, life is much simpler:  Long-press the RESTORE key to enter the Freeze Menu, and then press 8 to toggle the drive number of the first internal drive between 8 and 10, and 9 to toggle the second between 9 and 11, as you can see in these shots:

With this, you can easily have an external 1541 or similar on device 8, and do things like, say, load Sam's Journey:

Anton assures me that Sam's Journey is VERY smooth on the MEGA65.

Or better yet, see it in action:

Actually, one of the really great things about this post, is that all I did was a 5 minute fix to the Freeze Menu based on information that others had worked out, and the result was then tested by Anton.  That is, this is more of a post by the community and for the community, than it is a usual "what has Paul been making lately" post.  I hope that we see more and more of this kind of post, as the pre-series and then dev-kits and then retail versions of the MEGA65 get used more over time.


  1. love the sam's journey pic, because the computer looks so "real use"-like ;) with cables, cartridges etc on top ;)

    can't wait for my time of real use ;)

  2. so great to see the community is forming and picking up on this. great work on the GEOS port, BTW. I cant wait to see the full C65 GEOS running in front of me :) - thanks for all the amazing work you are putting into this!