C64 JiffyDOS installation.

Well tonight, I thought, I’ve got a bit of free time to install the first of two JiffyDOS roms for my Commodore 64’s. The first, would be installed in my beloved ‘breadbin’ c64 which requires a special 28-24 pin adaptor which I received yesterday from Jon – see post https://stiggyblog.wordpress.com/2011/11/22/dual-booting-jiffydos-for-classic-c64/ )

Now this particular computer is very dear to me as it’s my very first C64 that I’ve owned since the early eighties and has provided countless hours of fun over the past 30 odd years. As you can image, i was a little nervous working on it and not wanting to stuff this one up.

After work I dropped by my local Maplins store and picked up a couple of two-way toggle switches for each C64. With these attached to the new rom chip, I’ll be able to flip between original and JiffyDOS kernels.

Lid off, keyboard and power LED header disconnected….kettle on.


I found this rather handy JiffyDOS manual (.pdf) and had it to hand loaded in iBooks on my iPad. Tablets are great!


With the correct ROM chip identified for removal, I carefully (yep sweating a lot now) removed it with an IC removal tool. Surprisingly, it popped out without too much of a fight.

Next I dremelled out a small hole in the side of the c64 case to house the new toggle switch and also soldered the JiffyDOS fly leads to said toggle switch.

Lining up the JiffyDOS rom chip pins over the IC socket, checking Jon’s notes to see which way around it went and popped it into place.


I’ve left the fly leads loose inside the c64 case for the time being, and if all is o.k will wrap these into a neat line later on.

Everything put back together and ready for testing, and the original rom chip wrapped up in my spares box.


I won’t say how long I had my finger poised over the c64 on button 🙂


Woo hoo, all is working and testing shows everything is good…I hope?

I was playing Flimbo’s Quest via my SD2IEC yesterday evening so i thought I’d try it again with JiffyDOS installed. Whoa, it’s quick. I’m guessing here, but I’d estimate approx 300 – 400% quicker to load.

So that’s my older breadbin C64 completed, next is my late model C64c. This has the rom chip soldered directly onto the pcb board so removal isn’t as easy this time around. I’ve already had one attempt at desoldering it, but so far no luck. I’ll keep trying and as a last resort will cut away the chip and desoldering the remaining chip legs.

Huge thanks once again to you Jon.

##edit – thanks to my friend on Facebook for pointing out that something appeared to wrong. If you look back at the picture above the amount of free bytes is wrong, it’s missing about 25k. Strangely enough, it rectified itself and is back to the expected 38911 free bytes.




17 responses to “C64 JiffyDOS installation.

  1. Hey there. Well I’ve successfully removed the original kernel chip but there’s small amounts of solder left in the pcb chip holes. I can’t seem to get my iron hot/close enough to melt it and catch with the solder sucker. Bit of a pain really but I’ll keep at it bit by bit, hole by hole.

  2. Just hope you didnt burn out the traces by then. Its better to cut off legs the soldered chip and remove it. I told you its like welded on there.

  3. Yep, will have to be careful. I’ll keep at it but I’ve got another c64c board if I happen to stuff this one up 🙂

    Kind regards


  4. use some de-soldering braid to clear out the last of the solder (but not the crap from Mapplins) or heat up the solder in the holes as you push in the new socket.
    Dirty but it works

  5. Cheers Mike. I did try some braid but still no go i’m afraid. To be honest it’s not helping that my iron is a very cheap model which isn’t getting hot enough. Considering getting myself a solder station in the sales.

  6. Hi, did you manage to do the c64c in the end. I’m having the same problem – really trying not to bork the board.

  7. Hey Lee,

    No I’m afraid i haven’t yet as my woefully inadequate solder iron wasn’t helping much. Yesterday whilst at the Retro Computer Museum a friend of mine has loaned we his solder station and so i’m going to give it another go either later this afternoon or, as i’ve got the day off work tomorrow, thought I’d have a go then. Will let you know how I get on. It’s such a pain isn’t it! – but a skill i’m wanting to learn as i’m sure it’ll be useful in the future.

    Good luck and let me know how you get on with yours, would be great to hear from you again.

    Kind regards


  8. Hi Stiggy,

    I finally managed to do it. The solder melts at a rediculously high temperature. I spent an age trying to extract the solder with desoldering braid and it wouldn’t budge. Finally I got out the butane soldering torch and it started to come loose. Thankfully that worked, because I was going to get the heat gun out next 🙂

  9. Hey Lee, fantastic news glad you managed to get it sorted. I’m going to have one more go tonight before I threaten it with a blow torch 🙂

  10. I know it’s a long time after, but here’s some help – get a good solder station and then you can heat the solder from one side of the board and put the solder sucker on the other side of the board.. Heat – suck – done.

    You can also do this when an IC is giving you trouble – just put a light behind the board and you’ll see which pins still have solder – then put the tip on the top of the board on the outside surface of the IC leg – at the same time, have your solder sucker on the back of the board ready to go – you will feel the iron move down into the hole next to the IC let, then hit the sucker – done!

    I’ve got a Hakko 907 iron and a Hakko 936 station – got it at the flea market for $8. BEST thing I ever did – it makes you SO much better at solder/de-solder work. You’ll never regret getting a good iron.

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