"Portable" PiDP8

[Rick B]

Hi, all,

I've made my PiDP8 portable.   When I built the kit ages ago, I repositioned the Raspberry Pi so that there was better access to the Ethernet port and USB ports on it using a custom-made ribbon cable.   This A) allowed me to much easier provide an Ethernet jack on the back panel, as well as a couple of USB ports.

I recently read of a little gizmo called "Pi Sugar".  I got the Pi Sugar 3+ version.  It is a LiPo battery pack (5000mAh) with a full charge/battery management unit, designed using Pogo pins that connect the proper pins on the bottom of a Raspberry 3/4/5 board so that it can provide power to the Pi.    It comes with four screws that go through the mounting holes on the Pi into threaded inserts in the Pi Sugar board so that a secure connection is made between the Pi Sugar and the Raspberry Pi.  Since it connects from the bottom, it doesn't mess with the GPIO connector at all, and has no other connection to the Pi, making it very simple to remove if desired by just removing the four screws.

It has its own power button, which, if you single-press it, provides an indication on built-in LEDs as to the charge level of the battery.  If you press and hold for a second or so, then it does a countdown on the LEDs, and applies power to the Pi.   I have a USB to Serial converter that I can plug into one of the USB ports, and hook to a laptop to play with the machine, or, I can connect to it with WiFi, or plug it into Ethernet, and SSH to it.  I wired a simple connection across the power switch and brought it out to a nice pushbutton switch on the back panel of the PiDP8.   The Pi Sugar also has a micro USB input for power and charging, so when the machine is on display in my bookshelf of PiDPx machines, it runs from mains power just fine, and maintains proper charging and safety of the LiPo battery pack.  The battery pack is about the same size as the Pi Sugar board, and has a small connector that plugs to the Pi Sugar board.  The neat thing is that the Pi Sugar board has a Neodymium magnet glued to it, as does the battery pack, so the two just naturally snap together and are held together via the magnets.   It's pretty slick, and it all fits inside the PiDP8 case just fine.  I think it'd even work if you used the Raspberry Pi in its original location.

I wanted to see what happened -- so I took the PiDP8 and my laptop to a Starbucks that was pretty busy, and ordered a coffee, and sat down at a table, and powered up the PiDP8 and used a USB ethernet dongle on my laptop, and a short Ethernet cable to connect the laptop and PiDP8 together, and fired up a full screen terminal emulator, and played around in OS8, with the PiDP8 sitting beside my laptop, blinkenlights and all.

I got a lot of odd stares, of course, but some of them eventually came over to my table and asked "What the heck is that thing?"   Some thought it was some kind of hacking device that was trying to capture and decode other people's WiFi connections in the coffee shop, but after I explained, people thought it was really cool.   When I told them that this was a 1/3rd scale model of just a part of the machine, which took up pretty much a whole rack (including some kind of mass storage), they were astounded, and many had not a clue that this is what using a "minicomputer" was like.   I showed folks some web pages of real PDP 8/I systems, and they were blown away that this little portable thing sitting next to my laptop was at a minimum twice as fast as the real thing, and if the throttling was turned off, would run many, many times faster (It's running a Pi 4B+).   It made a good conversation piece.

I have not yet ran it long enough to see how long the battery lasts, but it happily ran the whole time while I was at the Starbucks and drank my coffee and visited with interested folks - probably about 40 minutes or so.   Then, I powered it down (long-press on the power button), and went about the rest of my running around.  When I got home, I plugged it into its power supply (via a jack on the back), and back it went on the display shelf, running OS8.    

 I want to make a TSS8 build with four to six sessions such that I could fire it up at Starbucks or the like, and invite people to TELNET to it, and login and play Adventure or some of the BASIC games in timeshared mode.   

My woodworking skills suck, and the back of the PiDP8 is not very nice looking because of that, with some poorly cut holes for the USB ports and the jack for external power, so I'm going to make a replacement panel that goes over the original wood panel (probably screwed into it at the corners) that will have much better cutouts for the USB ports, power switch, and external power.    I might even draw it up in CAD and have a provider like PCBWay or the like make it out of a thin sheet of aluminum.

The Pi Sugar would likely work just as well for a PiDP11, PiDP10, or a PiDP1.  The more blinky lights, the shorter the battery life would likely be, but the PiDP8 has quite a few, and it seems to d pretty well.

Just thought this might of of some interest.

Best to all,

-Rick

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https://www.pisugar.com