1541 Ultimate

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1541 Ultimate
Category Disk emulation hardware
Developer Gideon Zweijtzer
Year 2008
C64 software
C64 interface Expansion Port / Seriall Bus
Remote software
Remote interface
Remote platform
Website ultimate64.com

The 1541 Ultimate is a project by the Dutch hobbyist VHDL developer Gideon Zweijtzer. This is a Commodore 64 compatible expansion port cartridge that carries an Action Replay and Final Cartridge III (whichever the user prefers). Its main feature is fully-compatible FPGA-based Commodore 1541 emulation that is fed from a built-in SD card slot with C64 compatible files (e.g., .d64 disk images or .prg single program files) and connects to the IEC port of the C64 using a separate cable.

The difference between this and other SD based and .d64 mounting cartridges like the MMC64, Super Snapshot 2007, or MMC Replay is that the 1541 floppy (including its processor, helper chips, mechanics, and even sound) is fully emulated, resulting in very good compatibility.

File selection and management is done via a third button on the cartridge that brings up a new menu on screen. The 1541 Ultimate also works in standalone mode without a C64, functioning just like a normal Commodore 1541 would. Disk selection of .d64s is then done via buttons on the cartridge; power is supplied via a mini USB connector. There is a "Plus Version" available with an extra 32 Megabytes of RAM (as REU and for future use). The basic version has just enough RAM for the advertised functions to work.

The cartridge is slightly larger than a standard C64 cartridge, making it too big for standard cases. It is shipped "bare" with two stands at the far side to give it at least some stability.

The first batch of 1541 Ultimates were shipped in early April 2008 to all customers that had paid for it in advance, financing the production run. A second production run is already scheduled. Orders are handled on a first-come-first-served basis.

Other hobbyist projects similar to the 1541 Ultimate are the 1541-III and SD2IEC. However, these do not provide full 1541 emulation so compatibility with fastloaders etc. is very limited.

Features[edit | edit source]

  • Full emulation of a real Commodore 1541 disk drive.
  • Secondary 'IEC drive' for direct access to FAT filesystem.
  • FAT/FAT32 support, with subdirectories and long filenames
  • C64 cartridge emulation; Final Cartridge III, Action Replay, Super Snapshot, Commodore 1750/1764 REU
  • Flexible freezer menu to select, mount, create .d64 images, browse disk images
  • Configuration screen, with resident settings
  • 'Standalone mode' - powered through Mini USB connector, controlled through buttons and IEC.

Specifications[edit | edit source]

  • Board size: 68 x 96 mm
  • 250k-gate FPGA (flashable core)
  • Full size 6-pin DIN connector (IEC)
  • 512 kB SRAM
  • 2 MB Flash ROM
  • 32 MB SDRAM (Plus version only)
  • 2 emulated 6502 cores, one with the original clock (emulating the 1541 CPU) and the other with 25MHz (handling the .d64 management and SD-access)
  • Full size MMC / SD card compatible (Mini/Micro SD possible with adapter)
  • Stereo audio output
  • 6 pin expansion pin-header for connection to tape port (for C2N emulation), or other future features.

Links[edit | edit source]