PiDP8/I Step by Step

After attending the Vintage Computer Festival - East in April 2017 I learned about Oscar Vermeulen's PDP-8/I recreation. Please visit his web site if you're haven't already. It's a fantastic and easy to build kit. I share the following photos of my build along with few tips that might be useful to a new kit builder.


1. The excitement of opening the package!


2. We all want to start building right away, but performing an inventory is important. Be sure to separate the momentary switches (6 leftmost) from regular toggles. An organized workspace makes building easier and faster. Notice, too, that the side of the board that says "PiDP-8/I Front Panel" is the back of the board.


3. You can bend diode leads on angles for easy soldering. I recommend doing one lead on each diode, then going back and doing the second lead. That way you're sure not to overheat any.


4. Hard to see in this photo, but this is the board when all diodes are installed. Sorry that it's not in focus. I'd like to blame the camera, but it's surely the photographer.


5. The three 1k ohm resistors are now installed at the left, center and right, above the row of diodes. I like to position resistors so that the color bands are read from left to right or top to bottom. It's easier to double check values when you don't have to read backwards.


6. Here are the leads of 390 ohm resistors sticking through the back. I've begun snipping off the leads after soldering. As with the diodes, I soldered one lead of each resistor, then went back and soldered the second. Hold the lead before snipping. Otherwise they sometimes shoot off quickly. Avoid being speared in the eye.


7. The 390 ohm resistors on the top side of he board.


8. A sea of LED legs. Double check polarity...and then check again! I started from the center row and worked my way outward.


9. Now clip leads from outside edge working inward to center row.


10. It's taking shape. :-)


11. When soldering the IC socket, lightly tack two diagonally opposite corners. Then you can reflow the solder while pressing down on the socket to be sure it is against the board. Then solder the rest of the pins.


12. Use the same diagonally opposite corner technique on the header block. It's especially important to get it perpendicular to the board.


Header and IC socket installed.


13. I encountered my first challenge when discovering that the switches would not fit into the template board. The arrows show where not enough PCB was cut out. I used a square file and gently & slowly widened the five or six holes that needed it.


14. Fully widened holes. Time to proceed with mounting the switches.


15. Switches installed. Be sure to put the momemtary contact switches where they belong!


16. Mounting the Raspberry Pi. Cover the end of the standoffs when you clip them. They will really fly and any contact will be painful. I wish the Raspberry Pi were mounted toward the center of the board so that panel mount connectors could be used. With the Pi right at the edge you're limited to just cutting a hole.


17. Success!


18. I don't trust my ability to measure! I put cardboard on the ethernet and USB ports and attached adhesive tape, sticky side out.


19. After gently lowering the PiDP8 into the box, I slid it to the left so that the tape and cardboard would stick to the box. I lightly traced pencil lines around it.


20. I drilled a few holes and then filed, filed, and filed. And filed. Even at that, the woodworkers out there will get a good laugh at the results, but they're functional. I had to make the holes wider than the connectors because USB and ethernet connectors are wider. When I thought I was done I discovered I also had to file room for the ethernet clip. Because 2 USB ports are enough for me, I only cut open space for that many.


21. Because I didn't remote the Raspberry Pi with a ribbon cable - I really wish I did! - I had to compromise. I used a right angle micro-USB to bring it out the back. The hole is big enough to let the blocky body through. Then I used a right angle HDMI coupled with a flexible HDMI hanging out the back. No, not ideal, and others no doubt have done better, but really not bad either.


22. Close up on the holes for cords and connector.


23. Many photograph the smooth side of their PiDP8/I. Here is the ugly side.


24. And the front! That's the back of my wife's head popping up above the PiDP8/I in the background. Notice her lack of enthusiasm in photographing the completed project. :-) But that's ok. She's a great gal!

In closing, thank you, Oscar!

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