This is a old thread on forum64.de , i have translated it for you in english language. An old but very useful faq.

• C64 with Board Rev. 326298, 250407, 250425… (old C64 case):
• Rom 901227 (C64 Kernel) replace with 27C64 (8KB) Eprom. You need a special Adaptor 28 Pin Eprom to 24 pin Rom.

• C64C with Board 250469:
• Rom 251913 (C64 Basic & C64 Kernel) replace with 27C128 (16KB) Eprom. Without special Adaptor.

• 1541 with Board Rev. 154008, 154050, 250442, 250446 (old 1541 case):
• Rom 901229 (DOS Hi-Rom) replace with 27C64 (8KB) Eprom. You need a special Adaptor 28 Pin Eprom to 24 pin Rom.

• 1541-C with Board Rev. short motherboard (sometimes old 1541 Board in a new White Case):
• Rom 251968 (DOS Low-Rom & DOS High-Rom) replace with 27C128 (16KB) Eprom. Without special Adaptor.

• 1541-II:
• Rom 251968 (DOS Low-Rom & DOS High-Rom) replace with 27C128 (16KB) Eprom. Without special Adaptor.

• C128:
• Rom 251913 (C64 Basic & C64 Kernel) replace with 27C128 (16KB) Eprom. Without special Adaptor.

• 1570:
• Rom 315090 (1570 DOS Rom) replace with 27C256 (32KB) Eprom. Without special Adaptor.

• 1571:
• Rom 310654 (1571 DOS Rom) replace with 27C256 (32KB) Eprom. Without special Adaptor.

• C128-D Plastic Case:
• The same of C128 & 1571.

• C128-DCR Metal Case:
• Rom 318077 (C64 Basic, C64 Kernel, C128 Editor, Z80 Bios, C128 Kernel) replace with 27C256 (32KB) Eprom. Without special Adaptor.
• Rom 318047 (1571DCR DOS Rom) replace with 27C256 (32KB) Eprom. Without special Adaptor.

• 1581:
• Rom 318045 (1581 DOS Rom) replace with 27C256 (32KB) Eprom. Without special Adaptor.

source: forum64.de

download original roms: zimmers.net

It was written with the U1541 user interface in mind, and I hope I have achieved the same ease of use.

Features:

• Browsing much like the U1541 user interface.
• It even handles more than 256 files per directory. (now I know why Gideon wants to postpone that feature)
• Devices 8-11 are selectable.
• Basic load address information (verrrry useful for VIC users)
• ‘sys 320′ hook to reload browser (after a reset, or when it is overwritten by a file load)
• Only 8 blocks.

Read more…

Unfortunately, the first Batch-2 units shipped have a small issue. It turns out that the order of the cartridge ROMs flashed is faulty. Therefore, the Final Cartridge 3 and the Action Replay cartridges don’t work. You can fix this by applying the official V1.5 release that can be found in the download section. Of course, cartridges that are shipping from this moment on won’t have this issue.

source: 1541ultimate

The shipping has started! Remaining boards from batch 2 and 3 will arrive not long after. Please do NOT ask me when yours will be shipped. I don’t have time to answer that. Rest assured, that it will be as swift as possible!

source: 1541ultimate

Enjoy with this nice video of 1541 Ultimate cartridge from YouTube.