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  • JiffyDOS ROM Overlay with switch
  • JiffyDOS Logo
1.00 Ounces
Calculated at checkout

Product Description

JiffyDOS is a Disk Operating System (DOS) enhancement which gives your C-64 or C-128 the disk access speed it has always needed. A chip-for-chip replacement for the Kernal ROM in your computer and the DOS ROM in your disk drive(s), JiffyDOS achieves levels of performance and compatibility unmatched by other disk speed-enhancement products. Outstanding speed, solid compatibility with virtually all hardware and software, and a new set of desperately-needed commands and features, gives your system a new lease on life and the power to compete with today's newer, more-expensive machines.

JiffyDOS should not be confused with Cartridges, Turbo ROMs, Burst ROMs or "Parallel" systems. Ultra-high-speed multi-line serial technology enables JiffyDOS to outperform these products without any of their inherent disadvantages. JiffyDOS leaves all ports on your computer open, works with virtually all software, speeds up PRG, SEQ, REL and USR files, and does not require any extra cabling. Owning JiffyDOS also gives you access to some of the best product support available.

Instructions Manuals are provided online only and are available here: http://www.jbrain.com/pub/cbm/manuals/JiffyDOS/.  Please download the appropriate set when ordering. 

This product is the actual ROM IC that replaces the DOS or KERNAL ROM IC in your CBM unit.  The unit comes preprogrammed with the correct version of JiffyDOS.

If you are just looking for the ROM image files, they are available here.

NOTE:  We are running low on 24 pin JiffyDOS (64, SX, 1541, VIC-20), but will fill orders until we run out and we should have more stock by the end of the month.  We have ample stock of the 28 pin options (128, 64C, +4, 1571, etc.)

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Product Reviews

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  1. A Must-Have for any Commodore Device. 5 Star Review

    Posted by on 14th Apr 2016

    After researching upgrades to the C64, I decided this was one of the best, especially for the low cost. Upon installation, I was instantly amazed at how much easier it was to list and load programs off both my 1541 drive, and the uIEC board I bought. My next purchase from RETRO will be JiffyDOS for my 1541 disk drive. This chip is a must for any Commodore device.

  2. Perfect internal solution for loading time haul-4$$! 5 Star Review

    Posted by on 6th Apr 2016

    With an SD2IEC SD card reader this ROM really improves loading times. Games work with no issues, the compatibility was great!

    I also need the cart port freed up for something else so it's a perfect internal solution.

  3. Wonderful Product! 5 Star Review

    Posted by on 17th Mar 2016

    I bought JiffyDos to work with my C-64 Reloaded. It works perfectly! Glad to see people still supporting these old systems!

  4. Great quality 5 Star Review

    Posted by on 14th Dec 2015

    I was a bit worried about modifying my C64, but the installation went super-smooth, everything working first try. The build quality was top-notch and the results speak for themselves.

  5. Great product for C64 Reloaded 5 Star Review

    Posted by on 19th Nov 2015

    The JiffyDos Overlay-ICs work great with the C64 Reloaded board. Easy kernal switching using the RESTORE key!

  6. Best product ever 5 Star Review

    Posted by on 26th Oct 2015

    These are great and easy to use. Makes me wonder how I did without years ago. Great time saver. This along with uIEC reader and you are in for a treat.

  7. Tried and true... 5 Star Review

    Posted by on 21st Sep 2015

    While there may be other fast loading kernels out there for vintage Commodore users, none of them offer the compatibility, ease of use, and availability of JiffyDOS. For a few bucks you too can transform your loading wait times from a painful crawl to an outright sprint. Also features very powerful shortcut syntax for working with files and programs on disk without all the typing otherwise required. Combined with a uIEC, you'll have the most powerful Commodore storage solution around. All in all, JiffyDOS is a must have for anyone interested in hot-rodding their beloved machines. Bonus Protip- For those with multiple machines and an EasyFlash3, buy the overlay chip for your preferred floppy drive(s) or simply use an uIEC, and then buy a JiffyDOS kernel image license. After flashing the file to the easyflash cartridge, you'll be able to run JiffyDOS through the easyflash on any C64 you plug it into without further modifications.

  8. JiffyDOS for the 1541 Floppy Disk Drive 5 Star Review

    Posted by on 27th Aug 2015

    If you have a lot of old 5.25" floppies, this is the only upgrade you will ever need for your 1541 Disk Drive! The Kernal ROM IC comes with a two position switch attached, so it's ready to go. Installation is a 5 minute job and probably one of the cheapest upgrades you can get for your Commodore.

  9. Great value ! 5 Star Review

    Posted by on 28th Jul 2015

    The installation was easy and the results stunning !

  10. jiffydos 3 Star Review

    Posted by on 26th Jun 2015

    The overlay IC is not less than I expected in terms of functionality. I am disappointed though by the fact that it came with a 3 positions switch instead of a 2 position switch, so one position of the switch is just useless and confusing. I'll have to replace the switch myself making this mod to my c64 less straightforward that expected

Previous | Showing reviews 11-20 of 35 | Next

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