1541 Ultimate II+
FPGA cartridge that replaces the 1541 disk drive on any Commodore 64
1541 Ultimate II+: mass storage for the Commodore 64
The 1541 Ultimate II+ is an FPGA cartridge for the Commodore 64 that emulates the classic 1541 floppy disk drive and adds USB storage, a SID player and cartridge emulation.
Developed by Gideon's Logic Architectures, the 1541 Ultimate II+ plugs into the expansion port of any Commodore 64. It loads disk images directly from a USB stick, reproduces the 1541 drive sounds through a built-in speaker, and supports cartridge emulation, a RAM expansion unit and a built-in SID player. For C64 enthusiasts, it is one of the most capable and versatile accessories available.
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What is the 1541 Ultimate II+?
The 1541 was the standard floppy disk drive for the Commodore 64, and almost all C64 software was distributed on 5.25-inch floppy disks. Today, working 1541 drives are ageing, floppy disks deteriorate, and finding reliable hardware is increasingly difficult. The 1541 Ultimate II+ solves all of that in one cartridge.
Inside the cartridge is a Xilinx XC3S250E FPGA chip that recreates the 1541 drive logic at the hardware level. Disk images in .d64 and other standard formats are loaded from a USB stick. The result is near-perfect compatibility with the full C64 software library, including copy-protected titles that were notoriously difficult to handle even on original hardware.
Beyond disk emulation, the cartridge includes a REU (RAM Expansion Unit), a SID player, cartridge image support and an Ethernet port for network file access. It is updated through regular firmware releases, keeping compatibility and features current.
What the 1541 Ultimate II+ can do
- ▶1541 disk drive emulation: Load .d64, .d71, .d81 and other disk images from USB storage at cycle-accurate speed
- ▶USB and SD storage: Browse and load files directly from a USB stick without any additional hardware
- ▶Cartridge emulation: Run cartridge images including Action Replay, EasyFlash, Ocean, Final Cartridge and many others
- ▶Built-in REU: Up to 16 MB of RAM expansion, compatible with software that uses the REU for speed and storage
- ▶SID player: Browse and play .sid music files from USB, including the full HVSC collection
- ▶1541 drive sounds: A built-in speaker reproduces the original clicking and seeking sounds of the real 1541 drive
- ▶Ethernet connectivity: Access network file shares directly on the C64 without a PC acting as a server
- ▶Firmware updates: Regularly updated by the developer to improve compatibility and add new features
1541 Ultimate II+ in pictures
The 1541 Ultimate II+ is available in several colour variants. All versions are functionally identical, running the same firmware and offering the same features.
Who is the 1541 Ultimate II+ for?
C64 owners without a working disk drive
If your 1541 has failed or you never had one to begin with, the 1541 Ultimate II+ provides immediate access to the entire C64 software library from a single USB stick. No disks required.
Collectors who want to preserve their disks
Original floppy disks degrade over time. The 1541 Ultimate II+ lets you archive your disk collection as .d64 images and run them from USB, reducing wear on irreplaceable originals.
Developers and demoscene enthusiasts
The built-in REU, Ethernet port and cartridge emulation make the 1541 Ultimate II+ an invaluable development tool. Load and test software quickly, access network resources and push the C64 hardware further.
Anyone who wants to simplify their C64 setup
One cartridge replaces a disk drive, a cartridge collection, a RAM expander and a SID jukebox. The 1541 Ultimate II+ turns a C64 into a compact, versatile machine ready for any classic C64 games or software.
Firmware and compatibility
The 1541 Ultimate II+ is actively maintained. Gideon's Logic Architectures releases regular firmware updates that improve compatibility, fix edge cases and occasionally add new features. The firmware is shared across all current platforms.
Firmware version 3.12, released on 12 May 2025, is the current stable release. It is compatible with the U2, U2+, U2+L, U64 and U64E2 platforms, meaning the same firmware file works across the entire product range.
Updating the firmware is straightforward: download the file, copy it to a USB stick, and use the built-in firmware update function in the cartridge menu. Full installation instructions are available in the official documentation.
Compatible platforms
| U2 | Original 1541 Ultimate II |
| U2+ | 1541 Ultimate II+ (current model) |
| U2+L | 1541 Ultimate II+ Long version |
| U64 | Ultimate 64 motherboard |
| U64E2 | Ultimate 64 Elite II motherboard |
Technical specifications
| Chipset | Xilinx XC3S250E FPGA |
| Connection | C64 expansion port (no soldering) |
| Storage | USB flash drive |
| Speaker | Built-in (1541 drive sounds) |
| Ethernet | Yes (network file access) |
| Power | Via expansion port |
| Current model | 1541 Ultimate II+ (U2+) |
| Developer | Gideon's Logic Architectures (GLA) |
| Disk emulation | .d64, .d71, .d81, .t64, .prg and more |
| Cartridge emulation | Action Replay, EasyFlash, Ocean and others |
| RAM expansion (REU) | Up to 16 MB |
| SID player | Yes (.sid files from USB) |
| Firmware | Version 3.12 (12 May 2025) |
| Compatible platforms | U2, U2+, U2+L, U64, U64E2 |
| Available colours | Red, black and other variants |
| Firmware updates | Free, available at ultimate64.com |
Frequently asked questions
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