This is an electronic download os JiffyDOS for the Commodore 128. For physical ROM replacements of JiffyDOS, go here.

JiffyDOS is a Disk Operating System (DOS) enhancement designed to significantly improve the disk access speed of your Commodore 64 (C-64), Commodore 128 (C-128), Commodore VIC-20, Commodore SX64 or Commodore C16/C116/+4.

It functions as a direct replacement for the Kernal ROM in your computer and the DOS ROM in your disk drive(s). JiffyDOS delivers exceptional performance and compatibility that surpasses other disk speed-enhancement products. With outstanding speed, robust compatibility with nearly all hardware and software, and a range of new commands and features, JiffyDOS revitalizes your system, empowering it to compete with modern, more expensive machines.

It's important to note that JiffyDOS should not be confused with cartridges, Turbo ROMs, Burst ROMs, or "Parallel" systems. Utilizing ultra-high-speed multi-line serial technology, JiffyDOS surpasses these products without inheriting their limitations. JiffyDOS keeps all ports on your computer accessible, functions seamlessly with nearly all software, accelerates the loading of PRG, SEQ, REL, and USR files, and does not require any additional cabling. Furthermore, owning JiffyDOS grants you access to exceptional product support.

User manual and ROM building help can be found on our support wiki here.