exxos's Atari, Amiga & retro forum

OK, so building a crystal circuit is off the cards for now as I don't have any of the whacky capacitor values I might need as per @stephen_usher's mention of black magic.

I do however have this:


And I'm just figuring out how I can get the clock generator programmed. It seems all I need are SDA/SCL VCC and GND and I've used Clockbuilder Pro to generate the necessary code.

I just need a couple of pull ups for the I2C lines and I should be able to use Python and Blinka to program it.

Might then just have me a clock I can use in place of a crystal for the 800.

I might be missing something. But wouldn't be easier just to buy a non-working XL, or even two? Chances that the crystal would be still working, and you could get extra spare parts. Should probably be very cheap, I think.

Anyway, there is a full thread on Atariage about building custom PAL clocks:

https://forums.atariage.com/topic/35486 ... solutions/

ijor wrote: 23 Dec 2025 19:17 I might be missing something. But wouldn't be easier just to buy a non-working XL, or even two? Chances that the crystal would be still working, and you could get extra spare parts. Should probably be very cheap, I think.

Anyway, there is a full thread on Atariage about building custom PAL clocks:

https://forums.atariage.com/topic/35486 ... solutions/

Yes I did consider it but prices seem to be a bit high at the moment, even looking at 2600's which also have the same crystal.

Potentially non-working and dirty XLs (not advertised as having a power supply even) are around the £80 mark at the moment, as I discovered.

There are no cheap retro computers these days, even trashed ones.

stephen_usher wrote: 23 Dec 2025 22:30 Potentially non-working and dirty XLs (not advertised as having a power supply even) are around the £80 mark at the moment, as I discovered.

There are no cheap retro computers these days, even trashed ones.

My experience exactly.

If you can get to Derby on the 13th January you may be able to win a cheap 2600 in an auction...

https://www.the-saleroom.com/en-gb/auct ... 95c3dd3aec

:lol:

stephen_usher wrote: 23 Dec 2025 23:08 If you can get to Derby on the 13th January you may be able to win a cheap 2600 in an auction...

https://www.the-saleroom.com/en-gb/auct ... 95c3dd3aec

:lol:

That's unlikely I think and I'd rather not take a good working 2600 apart for the purposes of fixing the 800. Also, being an auction it could get more expensive.

I would add that getting the Si5351 programmed and working as a suitable crystal replacement is just something I want to do for fun and expanding my mind :)

If I can find something that's dead on the likes of eBay then that's another story.

What I do find shocking is the complete and utter lack of any 3.546894 Mhz crystals or oscillators, none even on Ali Express.

I spent quite a while trying to get the Si5351 programmed yesterday, however my Windows machine refuses to identify my FTDI232H as anything other than a serial interface and it needs to see it as an FTDI device in order to program the Si5351.

Will have to try on my Mac later.

It's programmed using Python and Blinka so any platform should work as long as the FTDI device is detected. I have a tool to generate the necessary registers for the Si5351 so that bit is OK.

Well annoyingly my Si5351 board seems to either be dead, fake or something else, but it isn't visible on the I2C bus.

On a positive note the FTDI232H does work and I can see I2C signals on the pins that are supposed to have them. They even reach the SI5351 board, but I just don't get an I2C connection.

So for now programming that clock generator is a fail and I don't have the parts to build anything else right now. Will see what parts I do have and make a plan. At this rate I could buy a dead 2600Jr and it would be cheaper than anything else, though I would like to still have a play round with the clock generator circuit as I think it would be useful.

Need to see what I have in my parts drawer that I might be able to use.

Given the crystal needs some weird value caps to set it up it might be a bust though.

@rubber_jonnie I'll be surprised if I don't have one. I'll send it with those chips when I get a chance.

PhilC wrote: 25 Dec 2025 16:28 @rubber_jonnie I'll be surprised if I don't have one. I'll send it with those chips when I get a chance.

If you do that would be awesome, but no hurry and have a great Christmas.