stargazer
Offline
SLC, UT

Just looking for some instructions to add a tri clock to my nes. I'm thinking half, normal, and 2x or 2.5x.
Essentially it would be a total of 2 additional crystals and a tri switch that would switch between the two crystals and then just bypass them for a regular clock.

Also a component source list would be helpful!

Its got to be dead simple, I'm just really bad at circuit design/logic. Also possibly would there be enough interest to do a run of osh park PCBs?

Apologies in advance if this comes across as lazy, I just figure there's people out there who could whip this up without even thinking about it.

Jazzmarazz
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Michigan

Here is an easy guide:
http://www.thejobbitt.com/nes-guides/ni … ing-guide/

You will need nothing more than the extra crystals and a switch (or two depending).

I made this just for you:

And here are the eagle files for anyone to use:
http://www.mediafire.com/download/2lxyr … switch.zip

I will draw an MSpaint picture of how the switch should be connected in our case.....

Jazzmarazz
Offline
Michigan

And here is the way to hook up the kits with SPST switches.

Two extrnal clocks:

Two extrnal clocks and original clock:

Three extrnal clocks:

Three extrnal clocks and original clock:

I cannot guarantee that the NES will not hang if switching clocks while it is powered on. Daisy chain kits and switches for as many options as you want. Remember to connect VCC and GND as well as to cut the trace from the PPU to the CPU.

Alpine
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UK, Leicester

i like you a lot jazz, please don't stop helping people!

stargazer
Offline
SLC, UT

Hey thanks a ton jazz! I sourced some parts and just have a few questions.

Here's my part list (sorry for screenshot, couldn't figure out a better way to share):

Will either of the switches I have here work?

What is the difference between the two 10mhz crystals other than size and price? Is there an advantage one way or the other?

I plan to get all the crystals here and use a breadboard to find the optimal speeds and what won't work.

Is there any interest in producing these in kits? A simple run of 100 could save a bit.

Jazzmarazz
Offline
Michigan

The last crystal on your list is a smaller package than what I put into the board, but I updated it just now to support both sizes.
Here is Version 1.1:
http://www.mediafire.com/download/5uiu8 … od_1.1.zip

The only problem I see with those switches is that you are not going to be able to mount them without hot glue or something similar. They also look to have a center-option which means there is NO connection at certain times. I suggest these:
http://www.jameco.com/webapp/wcs/stores … 2135857_-1

They are cheaper than your red switch and can be mounted with a single hole.

Apeshit
Offline

.

Last edited by Apeshit (Jul 17, 2019 12:35 am)

Jazzmarazz
Offline
Michigan
Apeshit wrote:

Maybe worth noting that since the sound chip and video chip are separate on the NES, you'll have fairly unfavorable results in trying this. It won't be like under/overclocking a gameboy.

Are you to say that the video and sound will become out of sync? Will we find video or sound glitches?

It looks pretty promising to me as shown here:
https://www.youtube.com/watch?v=g4m-wyFC5-M

The clock rate is only increased slightly, but still. Also worth noting is that the CPU divides the clock rate by 12, so a 10MHz crystal is going to be an underclock as opposed to the default 21 MHz.

Last edited by Jazzmarazz (Nov 10, 2013 8:18 pm)

stargazer
Offline
SLC, UT

Thanks for that switch. I just don't like the big long switches, but for the sake of convenice it may be worth it.

Also, upon further investigation it appears that changing the clock will not effect the speed games run but only the pitch of the audio.
I'm wanting to change the speed games run. Audio would be cool, but primarily I'd use this for playing games. Is there any known way to increase the speed games run?

Jazzmarazz
Offline
Michigan
stargazer wrote:

Thanks for that switch. I just don't like the big long switches, but for the sake of convenice it may be worth it.

Also, upon further investigation it appears that changing the clock will not effect the speed games run but only the pitch of the audio.
I'm wanting to change the speed games run. Audio would be cool, but primarily I'd use this for playing games. Is there any known way to increase the speed games run?

I want to assume that it is the xtal pictured in red here:

I cannot guarantee that until I open up my own NES and poke at her. Then again, there ia another oscillator to the toward the power/video board. It looks as though it could be this type of outoput, but idk just yet:


EDIT: Yup, I believe it is the red one;

According to that schematic, it runs to both the PPU and CPU. Make sure you only increase or decrease it in small increments because I cannot find any information of others doing similar.

It is a different type of crystal than the ones we used in the board I made, so you would have to cut PPU-pin-18 but not CPU-pin-29 to use it. At this piont, you're dealing with black magic and I don't really suggest going there without the input of others.

Last edited by Jazzmarazz (Nov 10, 2013 8:39 pm)

Jazzmarazz
Offline
Michigan

Bump, I wanted more input from you Apeshit.
There is no such word as unfavorable when it comes to custom and expressive audio, but are you suspecting there would be software crashes?

12ianma
Offline

I'm interested to see what the results would be. you might be able to clock the audio separate from video? this seems actually advantageous as far as kooky software/glitches

Jazzmarazz
Offline
Michigan
12ianma wrote:

I'm interested to see what the results would be. you might be able to clock the audio separate from video? this seems actually advantageous as far as kooky software/glitches

Yes, the clock inputs are separated from a single source. In most cases, the two processors remain in sync with the PPU running at a constant fraction of the CPU. There have been many successful PPU overclocks, but the CPU or 2a03 is unaffected and therefore the sound is unaffected.

I want to say that the main clock could be sped up, therefore keeping the two in sync. I haven't done any such mod yet and don't know how hot the ICs might run at higher speeds.

12ianma
Offline

what kind of results would you aim for? purposeful glitches or useful audio (as in produce chiptune)

Alley Beach
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clovis CA

I have about 5 NES's. If someone wants to send me some oscillators Ill definitley be doing some R&D

TSC
Offline
Milwaukee, WI

It's possible to connect a LTC to either/or and have them run independently. I ran NTRQ thru a few times for some interesting sample sessions, and while I don't have schematics, I do remember cutting a few traces.

It's been a few years, but I think I remember DSC attempting something similar.