5 ms·

Same here. What I'm fantasizing about is a kit with a set of compute modules in a "tower stack" with a power supply, with horizontally oriented boards stacked o

Same here. What I'm fantasizing about is a kit with a set of compute modules in a "tower stack" with a power supply, with horizontally oriented boards stacked on the height, with all compute modules connected to ports in the tower. And you could choose where the pin-outs leads - either straight out to connect to some electronics on the outside, or straight down to a router in the bottom. Then you could dedicate some pins on all boards to link to the router, making for a small compact HPC setup (easy to ventilate too) and connect stuff like per-module LED rows for module status info and whatever else you might like. Bonus point for a "split" tower with modules on both sides, folding down like some toolboxes do: https://www.howdentools.com/data/howden/ul/1406847600/1409331356b2885a151f3a0c2bea69246f9f1356c4.jpg https://www.howdentools.com/data/howden/ul/1406847600/140933...

VLM 11y ago
Google for PC/104 its exactly what you're looking for although its aimed at industrial control users (and unfortunately priced accordingly) Of course if you could guarantee a production run of 5 million then a contemporary PC/104 board could probably cost as little as a ras-pi. Note that there's PC/104 the concept and form factor, and another concept with the same name was a 104 pin header that was vaguely a PC/AT bus. After all, S-100 can do almost anything so an extra 4 pins shouldn't hurt anything LOL. Anyway my point is if you find references to the 80s era 286-AT level of performance bus, don't worry for a decade there's been stackable PCI equivalents and all that. Something to think about WRT "limited" PC/104 bus speed is its not like spec-ing gamer graphics cards... if the purpose of the bus is to connect a 4 kilosamples/sec 12 bit A/D converter, even something as slow as RS-232 would not be a limiting factor, for example.
- Natanael_L 11y ago
  Neat. Not exactly what I imagined but probably a lot more practical OTOH. I'd just like a standardized high speed interconnection port with power supply and a shared router of some form. Probably would be more plausible when high speed optical links becomes cheap and ubiquitous enough so that a single thin cable can be drawn from each module to an PoE equipped router, so there's not a large mess of wires. Then the on-chip pinouts could be used independently of the networking.
  - pjc50 11y ago
    "Optical" and "PoE" do not go together?
    - Natanael_L 11y ago
      One cable can hold both fiber and copper wires. I think some thunderbolt cables do that.
pjc50 11y ago
What's this stack for? I'd be very surprised if it beat PC hardware + GPU for MIPS or FLOPS per $ or watt.
- VLM 11y ago
  Agreed for a supercomputer design it would be awful, but for a stereotypical 99.9999% CPU idle applications, the big win would be total cost of ownership / capex. On a long term view from many decades of observation, the digital world is bifurcating into one world thats 100% utilized all the time in data centers or real time control or video gaming, and another world that's 99.999% idle but when its active the users want it infinitely fast. And the two worlds don't talk or cross pollinate and are gradually using separate hardware. Having spent some time in electronics labs, given experimental results with smoke emitting diodes, and given the GPIO ports, there is minimization of the total cost of hardware experiments. If you assume 5% of boards will be destroyed per PID/motion control lab, then minimization of board cost is key to minimization of cost of running the lab. Implementing a PC that costs 20 times as much but provides 100 times the performance would only result in increasing the cost of the lab by 20 times. There is also a total wattage ecological argument. I have a pi running a 3-d printer and it works great and only draws a couple watts, but the web application is extremely fat and pointlessly featureful "because the cycles are there so may as well use them" and its not like installing a 100 watt PC would make better prints, it would just make an even more elaborate UI to use all available CPU cycles thus burn more coal. A 300 watt tor node doesn't really do anything a 3 watt tor node does, other than burn 100 times the coal.
  - pjc50 11y ago
    Most of this is the case for using one Pi, but not a stack of Pies. Unless you have some sort of micro-AWS which turns off the 99% unused ones. Ten boards drawing 100mW at idle are the same as one board drawing 1W at idle.
    - pm90 11y ago
      Except that when one board fails out of 10, there are 9 others still alive whereas in the other case you are toast.

VLM 11y ago

Google for PC/104 its exactly what you're looking for although its aimed at industrial control users (and unfortunately priced accordingly) Of course if you could guarantee a production run of 5 million then a contemporary PC/104 board could probably cost as little as a ras-pi. Note that there's PC/104 the concept and form factor, and another concept with the same name was a 104 pin header that was vaguely a PC/AT bus. After all, S-100 can do almost anything so an extra 4 pins shouldn't hurt anything LOL. Anyway my point is if you find references to the 80s era 286-AT level of performance bus, don't worry for a decade there's been stackable PCI equivalents and all that. Something to think about WRT "limited" PC/104 bus speed is its not like spec-ing gamer graphics cards... if the purpose of the bus is to connect a 4 kilosamples/sec 12 bit A/D converter, even something as slow as RS-232 would not be a limiting factor, for example.

Natanael_L 11y ago
Neat. Not exactly what I imagined but probably a lot more practical OTOH. I'd just like a standardized high speed interconnection port with power supply and a shared router of some form. Probably would be more plausible when high speed optical links becomes cheap and ubiquitous enough so that a single thin cable can be drawn from each module to an PoE equipped router, so there's not a large mess of wires. Then the on-chip pinouts could be used independently of the networking.
- pjc50 11y ago
  "Optical" and "PoE" do not go together?
  - Natanael_L 11y ago
    One cable can hold both fiber and copper wires. I think some thunderbolt cables do that.

pjc50 11y ago

What's this stack for? I'd be very surprised if it beat PC hardware + GPU for MIPS or FLOPS per $ or watt.

VLM 11y ago
Agreed for a supercomputer design it would be awful, but for a stereotypical 99.9999% CPU idle applications, the big win would be total cost of ownership / capex. On a long term view from many decades of observation, the digital world is bifurcating into one world thats 100% utilized all the time in data centers or real time control or video gaming, and another world that's 99.999% idle but when its active the users want it infinitely fast. And the two worlds don't talk or cross pollinate and are gradually using separate hardware. Having spent some time in electronics labs, given experimental results with smoke emitting diodes, and given the GPIO ports, there is minimization of the total cost of hardware experiments. If you assume 5% of boards will be destroyed per PID/motion control lab, then minimization of board cost is key to minimization of cost of running the lab. Implementing a PC that costs 20 times as much but provides 100 times the performance would only result in increasing the cost of the lab by 20 times. There is also a total wattage ecological argument. I have a pi running a 3-d printer and it works great and only draws a couple watts, but the web application is extremely fat and pointlessly featureful "because the cycles are there so may as well use them" and its not like installing a 100 watt PC would make better prints, it would just make an even more elaborate UI to use all available CPU cycles thus burn more coal. A 300 watt tor node doesn't really do anything a 3 watt tor node does, other than burn 100 times the coal.
- pjc50 11y ago
  Most of this is the case for using one Pi, but not a stack of Pies. Unless you have some sort of micro-AWS which turns off the 99% unused ones. Ten boards drawing 100mW at idle are the same as one board drawing 1W at idle.
  - pm90 11y ago
    Except that when one board fails out of 10, there are 9 others still alive whereas in the other case you are toast.