FAQ for the Ultimate II and Ultimate II Plus cartridges

The Ultimate cartridge is a storage solution for your Commodore 64 home computer and will give you an excellent experience using this great machine. Some people even enjoy using the Ultimate cartridge with their Commodore 128 computer.

Information and resources for the Ultimate devices

Please read Gideon’s story about the Ultimate products. Read the specifications of the original Ultimate-II Plus cartridges. Read the announcement of the Ultimate-64 device and the update. Also read the Ultimate-64 project status.

You can buy Gideon’s products in his web shop. You can also buy accessories.

Make sure you have the latest firmware installed

Pleaes make sure you have the latest firmware installed. This F.A.Q. only covers subjects relating to the latest firmware.

Where can I find the latest firmware?

You can find an overview the firmware releases for the Ultimate products on this page: firmware overview.If for any reason the ultimate64.com website is down, you can also download the firmware on github.

I am still running firmware 2.6k or lower on my 1541U-II/U2. How can I upgrade?

Upgrading from 2.6k to 3.x is a bit different from what you’re used to. You will first need to upgrade to version 1541U-II Update 3.0 beta 7 using the update.bin in the root of your microSD card.

Once you’ve done this, you can download latest firmware and run the file that ends with .u2u to upgrade.

To revert to version 2.6k, use the revert.u2u that’s included in the 3.0 beta 7 archive.

You can find the 3.0 beta 7 firmware on GitHub.

How can I use the emulated SID as second SID for 2SID tunes?

The question: link to facebook posting.

I’m looking for information on how to use the emulated SID of the U2+ together with a real one to play 2SID files, but so far haven’t found enough to make it happen. I’ve fiddled with the settings and read the Sidplayer instructions but all I get is one (the C64 mainboard) Sid. Anyone know where I should look?

  1. Find out what address the second SID is using for the 2SID you’d like to listen to. The ultimate sid player that’s included shows the second sid address since firmware 3.2.

  2. Go to the Ultimate menu and press F2 (shift + F1) to enter the configuration menu.

  3. Select ‘Audio Output settings’

  4. Enable SID Left

  5. Change the address at SID Left Base to the address you saw in the ultimate sid player. Probably something like $D420 or so

  6. Go to ‘SID Left Combined Waveforms’ and choose the model the 2SID tune was composed for. Most likely 8580 since there are not many 6581 2SIDs.

  7. Go to the Left Channel Output and Right Channel Output and select for both ‘Left SID’.

  8. Make sure to plug a mini-jack in the line-out mini-jack port and connect it to your powered/active speakers or an amplifier.

  9. Run the 2SID file and have a listen ;-)

Btw, the address of the SID chip inside your c64 is $D400.

Does the U2 and U2+ support Easyflash Cartridge images?

Yes, both carts support EF. Since firmware 3.2 there is also support for saving to the EF cartridge image:

Technology Preview: EAPI Support for Easyflash, incl. but not limited to writing support. Please note that the changed crt file is NOT saved automatically. You can save it by “F5”, “Save Easyflash crt” in the file browser. The file will be saved with the filelname “module.crt”. Optionally rename the saved file to a more recognizable name.

Tip: turn off Ultimate Audio in the C64 and cartridge settings when using this feature.

Which USB2LAN adapters are supported by the 1541Utlimate 2?

Any USB2LAN adapter that uses an AX88772/-A/-B chip should work.

Can I control the Utlimate using a USB keyboard?

Yes you can!

You can connect a USB keyboard to the Ultimate cart and use that to control the Ultimate instead of using the buttons. Use the scroll lock key to enter the Ultimate menu and ESC will bring you back to the basic screen. You can use the keyboard to navigate the Ultimate menu, just like when you’re using the remote interface via telnet, or using the C64 keyboard.

Can I play SID files from the High Voltage Sid Collection?

Yes, the Ultimate comes with a built-in SID Player called The Ultimate C64 SID Player.

How do I use the built-in SID The Ultimate C64 SID Player

As of firmware 3.2 The Ultimate C64 SID Player has keyboard support.

Use the following keys:




fast forward

1 - 0

sub tune selection for tune 1 - 10


play next sub tune

play previous sub tune


go back to Ultimate menu

space bar

pause / resume tune

Keyboard support only works for PSID tunes and for RSID tunes that don’t run in a loop and when there is enough memory for the player. If the keyboard doesn’t work for a particular tune, then press the cartridge button (default middle button) to go to the Ultimate menu for selecting another SID or sub tune.

Can I play SID tunes using the network interface?

There are several ways to play SID tunes using the ethernet interface:

  • Use the remote interface using telnet;

  • Use the Acid 64 Player Pro SID player by Wilfred Bos.

This SID player has the ability to play SID tunes over the netwerk on one or more Ultimate devices. It is built to run on the Microsoft Windows Operating System. When using Wine, Acid 64 Player Pro will also run on macOS and Linux. This for version 4.0 and higher it is unknown if it runs using Wine.

How do I use T64 files?

T64 is a file format, or rather a container, just like the D64 disk image. Unfortunately the U2 and U2+ do not recognise it as such. This means that you cannot open this container using the return key and then choose enter.

Use the right cursor key to enter the T64 container and then press return for the contextual menu to pop up and then choose run to run the c64 programme.

How do I create a create a directory

To create a directory on the file system browse to the location you would like to create a directory. Press F5 and choose the ‘Create Directory’ from the contextual menu.

How do I create a formatted disk image

To create a formatted d64 or g64 disk image on the file system browse to the location you would like to create a directory. Press F5 and choose the ‘Create D64’ or ‘Create G64’ from the contextual menu.

What does insert blank disk do?

Inserting a blank disk in either drive A or B will insert a blank and unformatted disk image in the drive. This means you need to format the disk before you can use it. Please take note that the disk does not exist on the filesytem (yet). If you saved files on the disk, then make sure you save the disk before turning off the computer.

How do I copy files using the Ultimate file browser?

The Ultinate device allows you to:

  • copy files and directories accross the filesystem;

  • copy files and directories accross the microSD card and USB thumb drives.

  • copy files from the filesystem to disk images

  • copy files form the disk images to the filesystem

Use these keys for copy operations:

  • use space bar to select the file(s) / dir(s) you’d like to copy

  • use cbm + c to copy

  • use cbm + v to paste.

How do I rename files and directories on the file system?

To rename either a file or a directory simply select the file or directory and press enter. A contextual menu will pop-up, select ‘rename’ to rename the file.

Where are the manuals for the Ultimate II and Ultimate II + carts?

This FAQ is part of the current manual.

For both the Ultimate II and Ultimate II+ a quick start guide exists.

Another resource for some (old) documentation can be found here: http://rr.c64.org/wiki/1541_Ultimate#Documentation

Where are the manuals for the included emulated cartridge images?

You will need to google for that. Archive.org seems to have scans of several c64 cartridges.

The wiki rr.c64.org is also a great place to find manuals.

Flip/swap disk (mount the next disk without using the Ultimate menu)

Since firmware 3.0e there is this nice feature called: “seamless disk swap by pressing middle button at least 1 sec”

This allows you to mount the next disk when a game or a demo asks for it without entering the Ultimate menu.

It only works on disk images for which it is obviously that those disk images belong together E.g. “special game disk 1.d64” and “special game disk 2.d64” or “special game A.d64” and “special games B.d64” or “special game S1.d64” and “special game S2.d64”. or “image 1.d64” and “image 2.d64”, etc. etc. etc. It even recognises roman numbers.

How about the C128 and C128D(CR). Does the Ultimate cartridge work on these machines?

Yes, the Ultimate cartridges work on the C128, C128D(CR) but with some limitations. Bart was so kind to write down his findings and advice on how to get the most out of your C128 combined with the U2+: https://www.bartsplace.net/content/publications/1541ultimate128.shtml

Disabling the internal C128D drive

source: 1541ultimate.net forum

Most of the games and demos will only run from device #8. Even if you added a device number 8/9-Switch to your internal C128 drive, some games and demos do not like if there is a 2nd drive on the bus.

So, the good news: With S.T.F.U. you can disable your internal drive by software: https://csdb.dk/release/?id=160842)

  1. Set your 1541-U drive emulation to device #9 or OFF

  2. Start and run the file. (In my case I had to load it from disk - it does not seem to work if you DMA-start it from your 1541-U).

  3. Select and deactivate your internal 1571.

  4. Set your Drive A of your 1541-U to device #8 and use it as regular drive.

This did work on my C128D. It did not work on my SX64. However it might be of interest for C128D users.