There exist many fastloading systems for the Commdore 64/VC 1541 combination. Unfortunately, only a few work with the cost-efficient SD2IEC device, a most notable exception is the Dreamload loader system.

However, writing to "disk" is not supported with Dreamload. Due to the customized disk protocol, even using the standard ROM routines for saving require a reset to deinstall the loader system.

Is there a Commodore 64 Fastloader/Fastsaver system that is SD2IEC-compatible? Ideally, it should be an IRQ-loader (i.e. it doesn't affect IRQs during load) and provide a speed improvement for both, loading and saving.

2 Answers 2


Some people (e.g. here) recommends the JiffyDOS as the most compatible speeder. But I am afraid that SD2IEC is not "fast loader friendly".

From the C64 Wiki:

Are fastloaders supported?

In general, no. That said, sd2iec does have special support for a few well-known fastloaders.

Longer explanation: Fastloaders consist of a code portion running on the C64 and of code running on the floppy. sd2iec cannot emulate a complete 1541 since this would imply emulating a whole 6502 processor, several additional circuits, and the floppy's mechanism. A microcontroller's resources are just not enough for that (it's not only about processing power and timing but also memory requirements). This can be done using an FPGA though - see 1541 Ultimate. For sd2iec, it is possible to add special support for individual fastloaders to the firmware only (which basically means reimplementing the fastloader's code formerly running on the floppy for the ATMega controller). This has been done for a few well-known fastloaders (see feature list above).

Feature list


  • Support for Turbo Disk AKA Fast Load AKA Speeddisk fastloader
  • Supports the JiffyDOS fast serial bus protocol, the Final Cartridge 3 fastloader/fastsaver, DreamLoad, Exos, GEOS
  • I know that C64 Wiki page. But unfortunately, it does not mention fast saving. Is that supported by software Jiffydos solutions like SJLOAD?
    – Peter B.
    Commented Aug 25, 2020 at 21:14

According to the reverse engineered code at https://github.com/mist64/final_cartridge , The final cartridge III cartridge does indeed have fast saving routines for both cassette tape and floppy disk. So such things did/do exist. I can't say the same of SJLOAD, but the name to me implies loading only.

That code on github also contains a makefile target to build just the FCIII fastloader/fastsaver as a loadable .prg file, so perhaps this might meet your needs?

  • Awesome, thanks, I will try that out. I will leave the question unanswered until I tested the final cartridge III routines, perhaps there are some more ideas coming up until then.
    – Peter B.
    Commented Sep 2, 2020 at 14:30

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