Installing dual SID chips in your Commodore 64 with SID 2 SID


In the last episode, I showed you the incredible
musical keyboard for the Commodore 64. In this episode, I’m going to show you how I
installed the SID-2-SID board into my commodore 64 in order to get stereo sound with 6 voices.
The board does not come with any components populated so you’ll have to buy them yourself.
Fortunately, the instructions are pretty clear about what components you will need. The most
unusual and expensive part you are going to need is this wire-wrap style DIP socket. Now,
you could probably order all of these from an electronics distributor. In fact, I live
just a few miles from one of the nation’s largest: Mouser Electronics. But, this time
I decided to try buying all of these parts from ebay. I bought nearly all of the parts
from a single seller on ebay, that way I was able to combine to get combined shipping.
So all of the parts ended up costing me about $20. But, I did end up with enough parts to
built at least 5 of these things because most of the ebay listings require that you get
a handful of whatever part you need. Of course, that could be a good thing if you’re prone
to messing up and need spares. So I started the build by inserting the long-legged socket
for SID #1. Soldering these things is time consuming, but it’s actually really easy. Once the sockets were done, there were just a few components remaining to finish the whole
thing. OK, so this next capacitor actually matters which direction it goes. you can see
it is labelled with positive and negative signs. The negative is indicated by the stripe
down the side of the capacitor. The transistor took a bit of thought for me and it helped to reference this diagram. But with the silkscreen being on the opposite side of the board, it
did make it confusing. OK, so at this point the board was finished except for the filter
caps. And I didn’t know which filter caps to use until I knew what kind of SID chips
I was going to be using. And that brings up the other dilemma. You see, there’s two types
of SID chips. There’s the 6581 which runs at 12 volts. And the 8580 which runs at 9
volts. Now typically the older style breadbin uses the 6581, while the newer style 64c uses
the 8580 as well as the Commodore 128. So you cannot mix match SID chips in this thing.
Whatever type of chip you use in socket #1, you have to have the exact same type of chip
in socket #2. So, my plan was to use this Commodore 64c since I had two of them and
one of them was broken and wouldn’t power on. So I figured I could salvage the SID chip
from the broken 64c. So I began the process of disassembling the broken unit. Ahhhh. and there’s the precious SID chip. Before going any further, I thought it prudent to test
this chip by putting it in the working machine, unaltered, and see if it had sound. So I got
to repeat this process all over again. And we’ve arrived at this SID chip.. Time to pull it out and insert the second one. Next, I put the computer just enough back together
to run the testing program built into the MSSIAH cartridge. Alright, let’s try it.. That’s a good sign. Let’s go into… Daignostics. Audio. But, there was a problem. No sound from any of the three voices. The chip was
dead. Just to make sure i wasn’t crazy, I put the original SID chip back in there to
test it again. Alright, so I’ve got the original SID chip back in. And, uh. It seems to work.
So that was the end of plan A. I had no more 8580 SID chips available. Well, That’s not
entirely true. There is one inside my working Commodore 128, but I’m not about to scrap
this thing just to take the SID chip out of it. So, on to plan B. I have a working breadbin
64 which you saw in my last video. I thought I might have a spare somewhere in the attic.
I have crates full of old computers up there, some are working, many are not. I dug out an old crummy looking C64. This sucker has seen better days, that’s for sure. After a
brief test, I confirmed that this unit would not power up. So, time to salvage its SID
chip. After taking it apart, there was a problem. In this particular unit, Commodore didn’t
put any sockets for any of the chips. They’re soldered directly to the logic board. This
was going to be a monumental pain to get this thing out, and there was no guarantee it was
even going to work. So first, i had to unsolder and remove the RF shield from the bottom and
then a began the laborious process of desoldering the chip. It took about 25 minutes to finally
get all of the pins free. And it felt like such a victory to see that chip come out of
the board. But the big question to be answered was, did it work? So, much like before, I
removed the SID chip from the working C64 and tried this one. Success! All 3 voices
worked fine. So, then I could go ahead and install my filter caps since I knew which
type of SID I was going to be using. I also needed a way to hear sound from SID #2. Now,
my plan was to put an additional RCA jack on the back of the Commodore 64. I did a similar
modification to a Casio keyboard by drilling holes in the case and using panel mount RCA
jacks. This same process should be just as easy on the C64 as there is plenty of extra
space in the back of the case. But for the meantime, I just wanted a way to test the
SID-2-SID so I took a space RCA cable like this. I have a whole box full of them. So
I just cut the end off and stripped the end and soldered it right to the board. The last
step was to attach the chip select wire. The purpose of this wire is to tell the second
SID chip when it is being accessed by the CPU, because it’s mapped to different memory
address than the first one. It connects to this pin on the cartridge port. So, I popped
in the two SID chips and I was about to make C64 history, except I ran into one more problem.
This metal cage for the video chip was in the way. This was so annoying. I had come
this far and nothing in the documentation said anything about this. Of course, different
Commodore 64’s had different arrangements on the logic board. So it’s possible maybe
mine is a less common configuration. But, either way around, I had to do something about
it. So you know, the shield is there primarily to meet FCC regulations on RF emissions. So
I theoretically could remove it. But, I wanted to keep it because the top lid also acts as
a heat sink to keep the video chip cool. So, I decided to do some modifications. I used
cutters and pliers to snip off and remove a chunk of the side wall. And then, I used a Dremel on the top piece and cut a perfect sized chunk out. I gave it some new thermal
grease and put it back together and everything fit perfectly. Unfortunately, it still didn’t
work. I got sound from SID #1, but no sound from SID #2. Upon closer examination, I discovered
I had been a bonehead and put the transistor in backwards. So, I desoldered it and threw
it in the trash in case I damaged it. And I used one of those spares I told you about.
I put in the new transistor and tried it again, and lo and behold it worked! Alright, well,
I hope you enjoyed that. You’ll have to wait until the next episode for me to explore the
MSSIAH cartridge so that I can show you better usage of the dual SID chip. Oh and I would
also like to point out that although this was a huge pain and it took nearly 2 days
to complete this task, a lot of it was poor planning on my part. I should have had a dual
SID configuration tested and ready before the card even got here. Um, maybe even bought
a SID chip online. That might have made things a bit easier. Ummm.. Anyway, I will see you next
time.

100 thoughts on “Installing dual SID chips in your Commodore 64 with SID 2 SID

  1. You solder the RCA audio cable directly to it you savage! I think it's awesome that you can upgrade this old Hardware but what sorts of things would take advantage of that? If everyone and their mother is programming for three voices what would take advantage of all 6?

  2. I did this back in 1990 by stacking a SID atop the factory chip, adding a filter cap, and supplying an address wire. This seems overly complicated, but I guess the added circuitry was needed to accommodate either SID voltages.

  3. I did this as a teen, about 30 years ago or so. I seem to remember I just piggy-backed one 6581 SID on top of the other. Bend out the address and output pins, and solder connections directly to them. I don't think I had any additional capacitors, resistors, and certainly no transistors involved. By golly, I did love my stereo SID player. Thanks for sharing.

  4. At least the time you told you spent on this mod is the true time. That’s how it happens to me. I don’t get the time to set everything up ahead of time. I just have to work on it on the fly. Note to self about 2 days worth of time needed. Sounds fun. Always enjoy watching your videos especially when things go wrong

  5. David, ever run into issues with keeping electronics in the heat in your attic? I live in Texas too so I know how hot it probably gets up there haha. Just curious.

  6. 7:38 — alternative solution might have been to bend the pins on the long leg socket by about 5 or 10 degrees (assuming the board would still clear the plastic outer casing)

  7. +adric22 Dual new-old-stock MOS Technologies 8580's might be useful for that the8bitguy.com Dream Computer Project. I identified some current Western Design Center chips for the core: W65C816S6PG-14 CPU, W65C22S6TPG-14 Versatile Interface Adapter, W65C51N6TPG-14 Asynchronous Communication Interface Adapter. The IDT 71256SA12TPG SRAM (32ki x 8 bits) is a usable main/shared memory component, the Greenliant GLS29EE010-70-4C-PHE EPROM (128ki x 8 bits) a usable nonvolatile memory component for built-in test routines, an OS kernel, &c. But new-old-stock MOS Technologies HMOS IC's such as the 8564 NTSC 40×25 text and sprite display controller and 8568 NTSC 80×25-character display controller are still needfuls for video.

  8. I'd love to get my hands on some of those older machines but with the retro craze everything has doubled or tripled in price.

  9. You have become my favorite tech guy on YouTube. Mainly because you show a lot of C64 stuff. I have a weakness for C64, it was the system I learned how to write code on, when I was a kid in the 80s. Appreciate all your videos and info.

  10. Your final comments — that you should have been better prepared — are fair, but I would say this video perfectly illustrates how you have to expect things to go wrong, no matter how much planning you have done. What you show is a calm, methodical, careful, pragmatic and (above all) determined approach to resolving all the problems. Excellent!

  11. Fun fact : You could pull out the SID chip while the C64 was running and put it back in. The sound would disappear and come back

  12. Why would any smart person want 2 SID chips, especially when 1 SID chip sounds like crap? The Commodore SID chip is a poorly designed, noisy and tinny sounding piece of garbage. The Commodore Amiga computer's sound chip blows the doors off the SID chip. Even the Atari ST computer's Yamaha sound chip blows the doors off the SID chip.

  13. you know I just started playing fallout, and every time he cuts to a headshot in this video I feel like I'm playing it.

  14. I love when he gets into his attic, and moves the Amiga 500 off the box (WHY ISN’T IT IN A BOX??) he says “some of them don’t(work)

  15. why not use solder removal alloy when taking chips out? would probably take around 5 minutes, even less with hot air.

  16. Just connect the emiter to the emiter and the base to base, nothing to be c9nfused about because 90% of npn transistors collectors are in the middle

  17. I’m super surprised to discover that the 8-bit guy doesn’t own one of those fancy de-soldering vacuum guns!??! I shelled out the $110 or so, for the Gaojie S-998P. I think that this vacuum gun is fantastic, save my one single qualm: it’s hollow tip is sort of long, and so the solder passing through it can sometimes cool off, harden, and clog the tip before it clears the tube. I’ve used a little drill bit to clear it out. I’m going to cut the tube a little shorter to resolve this, once I own a replacement tip. Still, that desoldering gun (the 998 has two motors for a little extra power), loud and annoying as it can be, has been a very worthwhile investment. If you do as many electronics projects as I’ve seen in your videos, and because you’re often doing repairs and desoldering jobs on those old through hole boards, you’ll probably want to pitch for a decent desoldering vacuum straight away. I’ve loved ALL of your video series’, by the way! I’ve watched most of them and I keep tuned in, as I find you an excellent source of info. Keep it up with your videos, great job!

  18. 7:48 Just cut off the wire-wrap pins a bit on the left side of the SID and bend both sets of pins to the left so the SID2SID board angles upward slightly where the RF shield is.

  19. my pops once soldered a whole tube tv together, it was crazy complex, each channel had its own antenna tune and RGB adjustment vhf

  20. This begs the question as to what has to be soldered in if you're going to use SwinSIDs, out of sheer curiosity.

  21. The most I ever got to doing anything like this was making my own DDR dance pad and fixing the dead pixels on my Gameboy.

  22. Warning these chips very sensitive do not touch the pins. Your electricity discharge can destroy a sid

  23. i have no idea why i'm here xD other than i LOVE the format this guy has on all his videos 😀 being a 92's kid i have only a VERY limited memory of most of these parts. but it's still very fascinating to watch!

  24. You realise you had to cut the shield because you soldered all the components to the wrong side of the board, right? It should've been facing the other way and it wouldn't have interfered with anything.

  25. Love your videos on retro items. I am intrigued that the 2nd SID is mapped differently. Presumably this means other POKE locations. I have mapped MIDI chips in this way.
    But doesn't that mean any software has to be bespoke?

  26. "I have crates of computers in my attic"

    1 C64 goes for like, $100 nowadays. I love and hate you, you gloriously rich bastard.

  27. I think your problems would not have been avoided in terms of placement and the transistor being backwards had you put the components on the silk screened side of the board like they normally go on… Was this board designed backwards?

  28. Is this the same nerd dude who played the keyboard in revenge of the nerds? Nevermind I was thinking about the nerd who played that electric violin thingy

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