exxos's Atari, Amiga & retro forum

And here it is (a bit blurry though...):

I see that you used the Dremel method and left the upper part intact.

Yes, that was quicker and it doesn't expose the oscillator.

Even though I don't have a cartridge socket I thought I'd design a "floating bus" type filter.

It basically passes the address lines, UDS, LDS and the ROM select lines through 470R resistors with pull-ups behind which should clean up the signals and stop any ringing from propergating as much. I haven't bothered with snuffers on all the lines 'cos that's a lot of capacitors and resistors.

I've added a break-out or the address bus and lines on the cartridge side so it's easier to monitor them.

I've not yet routed it.

Now layed out and some silkscreen done.

Now, should I get it fabricated as I don't have a socket to use to test it?

This afternoon I was going through the old Betamax tapes, as you do, looking at the adverts and bits of programmes left on the end of the tapes.

I came across this *SO* 80s advert for the Olivetti M20. I have no idea what "bit power" is but apparently it's got more of it than the Apple III, PET, IBM PC and Sirius 1.

The PCBs for the cartridge port filter/break-out have arrived.

I got the width of the edge connector a bit too tight, so I'll have to file about half a millimetre off to fully push it into the slot. Easier to trim than to add.

Without fitting any components it at least doesn't stop the TT from firing up, which is a positive. So no shorts.

This morning I filed and made up one of the cartridge port filter boards, without a socket as I don't have one yet.


Well, well, well.... It seems that instead of a nasty ringing mess of a signal on the data lines I have a pretty nice wave form.


To recap, this is 470 ohm between the cartridge edge connector and the output with 10K pull-ups on all lines.

Once I get a socket I can then test to see if this allows NetUSBee etc. to work correctly.

stephen_usher wrote: 07 Dec 2025 11:13 This morning I filed and made up one of the cartridge port filter boards, without a socket as I don't have one yet.


IMG_4807.jpeg


Well, well, well.... It seems that instead of a nasty ringing mess of a signal on the data lines I have a pretty nice wave form.


IMG_4810.jpeg


To recap, this is 470 ohm between the cartridge edge connector and the output with 10K pull-ups on all lines.

Once I get a socket I can then test to see if this allows NetUSBee etc. to work correctly.

Nice job :)

In other stuff, I've been attempting to design and print station furniture based upon photos from the early 1980s...


Not quite there yet, but getting close.