Commander X16

On 11/11/2022 at 11:19 PM, neutrino said:

@Wavicle I wouldn't mind a separate thread with some more pictures and explanation on how it worked ?



How much power did it use?



 

I don't recall exactly how much power it used. I believe it was around 250mW before I added the YM2151 circuit. That old IC consumes about 130mW by itself.

The process of building the X16 on a breadboard was straightforward from a circuit design standpoint, a bit tedious and long from a "cut and strip wires" standpoint, and incredibly complex from a debug and signal integrity standpoint. I would joke at the time that if I walked into my office in the morning and didn't look at the breadboard 16 in a way that it approved of, I would spend the rest of the day with the oscilloscope debugging why it wasn't booting that day. The parasitic capacitive and inductive effects were huge.

@Wavicle I had an idea that maybe it would be possible to make breadboard computers less error prone and easier to build and maintain with a separate build of a backplane. Which would then be the bus which is connected to each individual breadboard with a ribbon cable having solid pins at the end to push into the breadboard. The backplane could consist of a socket + veroboard with ribbon cable soldered on or plain pins with crimped sockets on the ribbon cable.

So the end result would be a long bus plane to which separate smaller parallel breadboards next to it are hooked into. In the event of problems it would then be much easier to just unplug any module at will and reconnect as needed. Enabling efficient exclusion of the source to the problem. Maybe hotplugging would be possible too with some protection diodes etc.

 

If you did that with a partially populated RC2014 backplane, then you could fairly easily transition toan RC2014 card design. A fully populated RC2014 backplane looks like this:

The RC2014 backplane looks like the right direction. By placing a shelf above the backplane like the picture below with planks parallel to the backplane connectors it would be possible to avoid ribbon cable bends and get a more compact solution. Though it would probably be beneficial if the socket spacing is more like the width of a smaller breadboard plus some margin. Perhaps a bottom ribbon cable with crimped connectors would be a more cost effective solution? because PCB estate is likely to cost more than ribbon cable.

 

 

Yes, why I said "partially populated" ... You could have connector 1, 2, skip 3 & 4, connector 5, skip 6, 7 & 8, connector 9, skip 10 & 11, connector 12, 3 standard RC2014 connectors, 2 enhanced RC2014 connectors.

The problem is that the board will be too short physically.