The Naked Atari 800

[rubber_jonnie]

I hadn't realised that some 800's had Sally CPUs, but it makes sense now as it wouldn't work with a known good 6502.
...
I didn't realise 400's & 800's ever had Sally CPU's, you learn something new every day :)

I learnt about that not too long ago. I also thought that Sally started with the 1200XL. May be also in the latest 400/800 units.

But what I found out these last couple of days, thanks to some research motivated by this thread, is that Sally appeared much earlier, and that it seems that actually ALL PAL CPU boards are Sally based!

Well that's news to me as well!!! I honestly thought all 400/800's were 6502 only, so that is definitely something new and interesting. Glad I could help motivate your research :)

[rubber_jonnie]

OK, so I have mocked up my planned long term clock board for the 800 and it looks like this:

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I have a wired connector that will allow the ATTiny board and Si5351 board to connect together, and at the moment they are simply Blu Tac'd together. The Si5351 board is the smaller 2 clock output variant, but the lack of one clock makes a big difference. I don't think it needs a PCB, it is just 4 wires, 5V, GND, SDA & SCL.

I am looking at a board potentially for the ATTiny+3 clock board, and possibly something for the SMD boards that include a programming header, we'll see. Have been playing with KiCad today but it's driving me nuts...

No banana for scale, however there is an original Atari crystal on the PCB next to is so you can see that it's not much bigger.

[stephen_usher]

:dualthumbup:

[rubber_jonnie]

:dualthumbup:

The real thing worked out very well, no hot glue required :)

Annoyingly I forgot to take assembled pics before I installed it, however it worked out very well. I used screws/nuts to make a small standoff at 2 corners that ultimately held it all together.

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And I used a small plug/cable to connect the 2 together, so it can all be broken down into individual parts again if say you wanted to swap for an SMD ATTiny board instead. I didn't realise, but this much smaller board does actually have 3 clock outputs, not two as I originally thought and this board now has 3 clock, the PAL main crystal frequency, the PAL colourburst frequency and the NTSC main clock frequency.

However since the ATTiny85 is removable, it can easily be reprogrammed to just deliver whichever clock you want, and of course this could be for any machine.

Here it is running BoulderDash from my Fujinet SD card:

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And you can see the clock off to the right on the scope. I'll see what other build options I can come up with using the larger Si5351 boards, as although they're bigger it should still be feasible to do whatever you want/need with them.

[rubber_jonnie]

As I totally forgot to take pics of the clock solution yesterday, I just pulled it out to get some.

ATTiny side:

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Si5351 side:

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Orientation is important here because the socket on the LHS of this image has a power LED immediately above it labelled 'on'. If you place this on the same side of the nuts you risk crushing the LED so it's important to note this when assembling.

These other images just show left and right views:

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Note that the VCC, GND SDA and SCL connections are all handled via the plug. Red (5v) and black (GND) are fairly obvious, yellow is SDA and blue is SCL.

One other thing is that the pins for the socket are quite long, so I had to trim them down. I'm going to do an alternative using the SMD ATTiny board as soon as I have the small clock boards with a socket. I'll also add versions using the larger clock board and both ATTiny types.

It should be noted that this isn't the only way to assemble these things and it may well depend on the space available in your machine.

[rubber_jonnie]

I put together a slightly different version over lunchtime:

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Nothing spectacular, just the power and GND pins tied together on both bards and an SMD ATTiny board in place of the DIL board.

[rubber_jonnie]

Just for fun I swapped the ATTiny for one with the NTSC clock and dropped the NTSC CPU board in and the machine just works, all that was required was a quick tweak of the colour pot to get it looking correct.

:)

[PhilC]

I've got a Pokeymax that I was thinking of putting in to my 800 but haven't looked how hard it is or where the pokey actually is.

[rubber_jonnie]

I've got a Pokeymax that I was thinking of putting in to my 800 but haven't looked how hard it is or where the pokey actually is.

It's nice and easy to get to:

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Right behind the PIA though I'm not 100% certain what space there is inside the faraday cage. I reckon it'd fit though.

I have one in an 800XL and 65XE that have both also been upgraded with PokeyMax, U1MB and VBXL/XE. My audio comes out of the 1088XEL style 13pin DIN (Like an ST's) video connector, but I expect you'd be able to run an audio cable out of what was the UHF cable hole, assuming you've removed the UHF cable like I did in favour of the DIN connector for composite on the side.

Hmm, maybe I need a PokeyMax for my 800 since it has an Icognito Gold installed.

[PhilC]

Thanks @rubber_jonnie. I have a big crack in the top case of the 800, so I take the case off as little as possible.

I should probably get round to stabilising the crack when I fit the Pokeymax.