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Commander X16 Changes are coming!


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Hello Everyone! I know it's been awhile since there has been an update, so here goes:

Earlier this year I had mostly completed the "Proto #2" motherboard. It was a mad dash to get the PCB made before we met in New Jersey at VCF. Right at the end, @Frank van den Hoef made a pretty substantial change to the VERA, which required a bit of reworking. April came, the trip was cancelled and life went sideways for a bit for the world. As such, I decided I needed to focus on a few things for TexElec, and took a bit of time off from the project.

Last month I picked up where I left off and planned to make minor changes for the VERA and get the PCB made. However, the team had some time to think and oversights and optimizations became apparent. One change led to another, and let's just say, we're gonna break some code. Sorry. 1f642.png🙂

I do believe the changes made will not disappoint. I'm not going to reveal them just yet. I am still laying out the PCB and would like to do some testing to make sure it's going to work as designed. I am trying not to release too much of the schematic until the end, as anything is subject to change at this point.

The pic below is how I have the expansion bus pinned out. I may well move some the pins around to simplify layout, so again, not in stone yet, but I do think this is pretty close to what pins will be present. This post is majorly TLDR already, so I'll add a comment below with more info on the pins, and the idea behind some of it.

Take care!

x16 bus.png

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On 6/4/2020 at 9:43 PM, StephenHorn said:

I couldn't help wondering if something major was in the works, given how slow the x16-emulator repo has been recently to discuss, approve, or deny pull requests. I'll be excited to learn more about the changes to the system!

Rest assured even if things seem to slightly pause "publicly" in certain departments, there's always a ton going on behind the scenes. Our Slack channels are buzzing every day and emails flying back and forth between China and here, as we work towards releasing the best incarnation of that retro dream computer possible.

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  • 3 weeks later...
5 hours ago, BruceMcF said:

That's a relief to see the +/-12V lines outside the VCC and +3.3v lines, rather than next to signal lines.

it's almost as if it was daring you to plug the cards in backwards. 

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On 7/6/2020 at 1:16 PM, -N2 said:

it's almost as if it was daring you to plug the cards in backwards. 

I think it is rather assuming (and probably correctly) that given the wide range of technical backgrounds in its audience ... there WILL be people who WILL plug cards in backwards.

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  • 3 weeks later...

I wounder what the mechanical interface would be.


Given the approach to "low cost off the shelf components", I'd assume one might use ISA connectors for that, since they are still being made and widely available at reasonable prices.

In order to prevent someone from sticking in an ISA card, which will be incompactible, it might be useful to insert the slot 180° horizontally rotated and have it aligned so that expansion cards are oriented like PCI/PCIe cards, making installation of ISA cards impossible.

This way, production of said expansion cards would also be cheaper - espechally when they do want to provide I/O outside of the case [like a network controller/"transparent modem"]...

Also since ISA edge connectors are relatively big and chunky, they also lend themselves as a good basis for people who might want to DIY and prototype said expansion cards.


Not to mention that additional pins of a 98-pin connector might also allow additional voltages or connection options to internals - i.e. IEC or joystick ports or serial ports or even audio, thus making modifications even easier as well as allowing more modularity and upgradeability without sacrificing the minimum viable goal.


Personally, I do know someone who might be interested in developing some FPGA-based accelerator for the X16 and having some expansion interface ready early on will greatly support both hardware and software development as well as making an independent aftermarket possible.

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12 hours ago, Kevin Karhan said:

I wounder what the mechanical interface would be.


Given the approach to "low cost off the shelf components", I'd assume one might use ISA connectors for that, since they are still being made and widely available at reasonable prices.

The physical format is stated, it's the same as the Apple2 backplane connector. That is still in production -- even if it is more for the industrial market which also uses them than the Apple II market

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5 minutes ago, BruceMcF said:

The physical format is stated, it's the same as the Apple2 backplane connector. That is still in production -- even if it is more for the industrial market which also uses them than the Apple II market

the more I think about it, I'm OK with it using a proprietary bus pinout with a connector compatible with the vintage Apple II, at least we can use the proto boards available for it! 

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  • 2 months later...
14 hours ago, Wesley Mays said:

What's going on with the BUS_L and BUS_R pins on that header? Are these audio lines? Are you sending expansion audio from the cards to the motherboard?

Maybe they're business lines.  You know, business left, and business right... oh ok it was a terrible joke to begin with.

 

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On 7/5/2020 at 4:16 PM, BruceMcF said:

That's a relief to see the +/-12V lines outside the VCC and +3.3v lines, rather than next to signal lines.

Also, I just noticed that they're mirrored... so, unlike some bus ports I've seen, plugging the card in backward won't immediately short VCC to the ground, or something stupid like that. 

Obviously, the card won't work, but it'll basically just muck up the address and clock lines, preventing the system from running. It doesn't look like a reversed card would blow up the computer or the expansion card. 

 

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  • 4 months later...
1 hour ago, Terrel Shumway said:

Does someone already have a KiCAD footprint for the card edge, or a drawing so I can create one?

I may be wrong, but I think there's still no public information about any PCB because there's still nothing final and things can change. So, creating any piece of hardware for the platform at the moment is not possible.

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4 hours ago, Terrel Shumway said:

Does someone already have a KiCAD footprint for the card edge, or a drawing so I can create one?

Since the Apple II connector is being used, I would imagine that there are probably some footprints out there, as expansion cards for the Apple II are still being made, albeit at 'boutique' scale...

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  • 5 months later...

I'm hoping that I'll be able to develop some hardware cards for the CX16, mainly as a hoist prototype board. I see +12,-12 and +3.3 V on the connector, but no + 5V one.  I assume that a simple 7805 regulator on the board will be retro and support all the old 5V retro logic chips that I have. 

I know there are much better regulators out there but the old 7805s are what I have in my parts bin.

  

Edited by Edmond D
typos!
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8 minutes ago, Edmond D said:

I'm hoping that I'll be able to develop some hardware cards for the CX16, mainly as a hoist prototype board. I see +12,-12 and +3.3 V on the connector, but no + 5V one.  I assume that a simple 7805 regulator on the board will be retro and support all the old 5V retro logic chips that I have. 

I know there are much better regulators out there but the old 7805s are what I have in my parts bin.

  

VCC is +5V.

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On 3/5/2021 at 8:45 PM, Dmian said:

I may be wrong, but I think there's still no public information about any PCB because there's still nothing final and things can change. So, creating any piece of hardware for the platform at the moment is not possible.

Now that some comments have brought this up toward the top of the queue, I'll note that I believe that @Kevin Williams has mentioned that they've shifted to a slot with some more pins.

It's not yet documented with the above level of detail, but they are busy working on getting key parts of the system working well, so as always, patience is in order.

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