#31 (Rack Configuration) is alive and well

[Alen Shapiro]

#31 (Rack Configuration) is alive and well. All the LEDs, Switches and diodes worked perfectly.

It took me a few hours every day for about a week to build the rack configuration. Every time I came across a confusion or needed to research something more carefully, I took notes in case a clarification or correction might be of general use. Here are the notes.

==========================

In: https://obsolescence.dev/pidp-1-building-instructions.html

Section 2. Soldering the main PCB set: Diagram 3

“Add 5 more resistors” should read “Add 4 more resistors” (find the 5th resistor whose name is Waldo!).

Section 3. Test the PiDP-1 to see if everything works

When run, the test program at /opt/pidp1/test.sh displays:

“If all switches are set UP and RIGHT”
It should display:
“If all switches are set UP and LEFT”

Equipment issues
Was short 4 x 1N4148 diodes - I used 6 surplus from old PiDP-11/70 kit, keeping one controller fully populated with old-kit diodes… they worked just fine.

A couple of boards were not pre-separated (e.g. Ottopanel (Ref. #9) and Ref. #10). Not difficult to do manually.

Why are 6 plastic wire protection DE-9 sleeves included. DE-9 for space war controllers just needs 1.

8 Red switches: 3 of them came with 3 nuts, 5 of them came with 2 nuts. Did not have enough nuts to start with to populate all 8 with 2 internal and 1 external. No biggie, I used 1 internal and 1 external per red switch. Now I have 5 surplus nuts. Too many nuts work here, anyway!.

Section 5. Build the game controllers

(1st instruction line says) “Start with cutting the supplied cable into two pieces, one for each controller”…Nope…. Don’t cut the supplied cable if two are already in the kit (as in mine)!

In the section titled “The DE9 connector on the other end of the cable”. To the right of the last open DE-9 picture, the large block table that gives all colors and pin assignments

Colors assigned in the middle block diagram are wrong, colors used in big block diagram do not match the two smaller blocks below it (for Controller1 and Controller 2), or “Back side” color assignments shown in a picture a few above it (in “The two controllers” section).

Largest Table should contain the following associations:
Red = row: pin 1
Green = fire: pins 5 and 9
Yellow = thrust: pins 4 and 8
White= right: pins 3 and 7
Black = left: pins 2 and 6

There are 2 Ref. #K, Ref. #L printed items. Ref. #K and Ref. #L, that are needed earliest, are hidden as punch-out items on speaker frame (the other two label duplicates are the badges but it’s quite confusing to find these earliest and it’s not obvious the correct two pieces require more searching).

No reference is found for the use of the 2 church-window shapes and 6 oval tabs punch-out blue plastic on the speaker frame (Ref. #N). There’s a visible hint in a couple of pictures that the church-windows are used to link the speaker section to the racked main console below it. Using the oval tabs under the 6 remaining black metal screws between the sound panel facia and the foam, get in the way of the T-bar separation spacing. Ultimately I did not use the oval tabs at all.

In: https://obsolescence.dev/pidp-1-rack-building-instructions.html
Open section titled: “Use three of the four aluminum profile to construct a U-shape” the caption of the first picture in this section says:

“Not shown are the 4 stand-offs that can be mounted to the back of the profiles, and the 5 T-bar separators that go between each of the panels.”

That’s was very cruel as only 4 T-bar separators are supplied. I panicked until I cross referenced the package contents in: https://obsolescence.dev/pidp-1-building-instructions.html
(section “Additional Parts List for the PiDP-1 Rack version”) which states “4 aluminum T profiles (spacers between panels)”.

That's it for now... back to playing Spacewar!

(Thank you, Thank you, Thank you, Oscar and crew).

[David Adams]

Wait a minute... the rack version looks like that?!?  Wow, did I make the wrong choice!  I'm about to build the console version now, so I will just have to live with it... ;-p

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[R Clark]

I like it.  I would have liked to get the rack PiDP-1 ... but I really don't have room for it, so I'll console my self with just the console front panel.  Glad it all worked out.

[Oscar Vermeulen]

 

It took me a few hours every day for about a week to build the rack configuration. Every time I came across a confusion or needed to research something more carefully, I took notes in case a clarification or correction might be of general use. Here are the notes.

VERY much appreciated! It is the best way to improve the building instructions and the experience for later builders. 

“Add 5 more resistors” should read “Add 4 more resistors” (find the 5th resistor whose name is Waldo!).

Fixed, Waldo has been removed :-)

...and I updated the Building Instructions with your other comments as well, much appreciated! You caught some important mistakes/omissions/confusion-causers.

These Building Instructions sort-of emerge as we are building the prototypes. And both I and the proofreaders, over time, become blind to the little mistakes and small things that can cause confusion. So we caught a good few of them now.

 

Equipment issues
Was short 4 x 1N4148 diodes - I used 6 surplus from old PiDP-11/70 kit, keeping one controller fully populated with old-kit diodes… they worked just fine.

Apologies for that, last week we added another check to ensure we don't make this mistake again. We count the diodes by weight, now improved the checking.

Glad you had ax extra diode!

 

A couple of boards were not pre-separated (e.g. Ottopanel (Ref. #9) and Ref. #10). Not difficult to do manually.

Indeed - we now do it ourselves.

The reason for joining the Ref9 and 10 is that actually, the PCB manufacturer is not always 100% consistent in their paint color! We found that out the hard way. The differences might be small, but I wanted to make 100% sure that the top and bottom panel have the exact same colour. And the only way is to join them during manufacturing...

 

Why are 6 plastic wire protection DE-9 sleeves included. DE-9 for space war controllers just needs 1.

The DE-9 case is a standard package, it just comes with sleeves for different cable thicknesses.

 

8 Red switches: 3 of them came with 3 nuts, 5 of them came with 2 nuts. Did not have enough nuts to start with to populate all 8 with 2 internal and 1 external. No biggie, I used 1 internal and 1 external per red switch. Now I have 5 surplus nuts. Too many nuts work here, anyway!.

Here too, we improved the packing checks. So the standard trademarked phrase is used once again: This will Never Happen (Again) (tm) :-)

Apologies. Indeed, you don't need all of the nuts but if you want, tell j.leon@ceds and he'll send the missing ones.

 

Kind regards,

Oscar.

 

[Oscar Vermeulen]

On Sunday, October 5, 2025 at 1:55:31 AM UTC+2 david...@gmail.com wrote:

Wait a minute... the rack version looks like that?!?  Wow, did I make the wrong choice!  I'm about to build the console version now, so I will just have to live with it... ;-p

No, we can send you the add-on parts for the Rack version later on if you want. But give us a few weeks to get up and running. Jose is overloaded at the moment with making more PiDP-1s, and the second batch of Enigma Touches for which he just received the parts. But email me if you feel at some point you need the PiDP-1 to Get Racked :-)

[Alen Shapiro]

Thanks Oscar, the most fun I've had soldering in a long time :-).

The only outstanding documentation issue I can see causes the Spacewar controllers to switch right/left with fire/thrust. Since the Hyper button connects right+left, in its current documented state, the Hyper button causes both thrust and fire to trigger. A little tricky to fix in the documentation. Here's the fixed picture:

compared to the original (unfixed) picture:

While that fixes the connections and function labels, it still leaves the 6 immediately prior DE-9 pictures showing the wrong colors. The alternative fix i.e. leaving the pinout diagram unchanged and just changing the 3 pictures at the start of the section ("The two controllers"), will leave the pinout functions in the original table (above) still wrongly associating colors and functions.

Changing subject...

Do you know of a cross compiler for C -> PDP-1 (or, perhaps, a PDP-11 -> PDP-1 machine code translator)? Getting some of my MI-generated rule-based C code running on the PiDP-1 would be sooooo Steam Punk!

Thanks again, and regards,

--Alen

[Oscar Vermeulen]

Alen,

On Tuesday, October 7, 2025 at 10:34:27 PM UTC+2 sof...@gmail.com wrote:

Thanks Oscar, the most fun I've had soldering in a long time :-).

For me, the idea that you can do construction with PCB panels, as in the case, was a bit of a revelation. I'm still surprised that the resulting case is just as good as anything manufactured. It opens to way for many other ideas.

 

Here's the fixed picture:

Thank you, thank you, thank you. I have this Brain Fog that makes fixing this a strangely difficult job. The fixed picture is already on the site.

...oh, but wait... you send the old picture twice, not the fixed one :-)

So glad I am not the only one to get confused by wiring.

While that fixes the connections and function labels, it still leaves the 6 immediately prior DE-9 pictures showing the wrong colors. The alternative fix i.e. leaving the pinout diagram unchanged and just changing the 3 pictures at the start of the section ("The two controllers"), will leave the pinout functions in the original table (above) still wrongly associating colors and functions.

Now I am extra puzzled - I made those pictures of my own game controller, and I tested that as known-good. So I am quite sure those photos are correct.

...or are you referring to the issue that sometimes, cables come with a different mic of colours? 

 

Changing subject...

Do you know of a cross compiler for C -> PDP-1 (or, perhaps, a PDP-11 -> PDP-1 machine code translator)? Getting some of my MI-generated rule-based C code running on the PiDP-1 would be sooooo Steam Punk!

Amazingly, yes.

https://github.com/fkokosinski/pdp1-playground

 

I have not tried it yet, because if I do, I'll never practice PDP-1 assembly. Curious to find out if it actually works, though! If you try, let us know in a freshly-labelled post thread - there will be some interest I am sure!

Kind regards,

Oscar.

[Alen Shapiro]

Hi Oscar,

Thanks for switching the picture. It can be tough to see but the old picture showed this:

while the new picture shows this:

Following just one of the "fixed" lines, e.g. pin 5 = green = fire and comparing it to the wired controller picture (middle picture at start of "The two controllers" section) shows the green wire properly connected to the fire control:

whereas the original pinout diagram would have connected the green wire to pin 2 which would have made the craft spin left. Unfortunately the 6 previous DE-9 pictures (previous to the pinout pic) show (among others) the green wire incorrectly connected to pin 2 e.g.

 

Perhaps, to make yours work, but keeping your batch of 6 pictures, your controller "back side" would have to be wired left to right: green, yellow, white, grey, brown?

Oh well, enough confusion for today. I'm off to go check out the cross-compiler (gcc->PDP-1), thanks so much for that link. I'll report back in your new thread.

Regards,

--Alen

[Adam Thornton]

Oh wow.  I thought I was just really bad at following directions, since it took three tries before I had the Spacewar controllers working correctly.  As a result, though, I can tell the controllers apart easily, since the wedge now has a cable several inches shorter than the needle, and since the wedge is a shorter ship, it's easy to remember.

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[Oscar Vermeulen]

Ouch ouch ouch.

I temporarily added a link to this thread in case anyone is building the controllers tonight. Will fix the Instructions tomorrow and check by building a new controller. And update photos from that.

Kind regards,

Oscar.

[Unibus]

Hi,

In the instructions I didn't see any reference to populating the I2C Connector J2. For future expansion it would be preferable to have this connector installed before the Raspberry Pi's GPIO connector. May be just a note in Step 4 that it would be appropriate to now fit this optional connector. This would be the obvious connector for a multichannel, Analog to Digital converter, possibly a real time clock, etc.

Regards,

Garry

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[Matthias Barthel]

Your'e right, but its not difficult to solder the pins later. I silder my i2c pins later because i use them for iot devices (i my case leds for testing)

Matthias 

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[sunnyboy010101]

Does anyone have a jpg or pdf of the schematic, showing the 9-pin serial functional connections (i.e. 'row', 'left', 'right', 'fire', etc)? Or a jpg of the 9-pin connector likewise labelled by function? It seems to me that given different wire colors in the kit, wiring by function would be much easier. (at least for me). The functions are clearly shown on the actual controller, so it's easy to trace which color wire is 'row', for example. So then soldering the 'row' wire to the 9-pin connector would be simple if one knows which pin is 'row' (or 'fire', 'right', etc.)

-R

p.s. yea, I know I left my controllers till very, very, very last. I was more interested in getting sound then video (and sound) and finishing up mounting the rack than playing with the controllers. Probably because I always sucked at spacewar! :-D

[Bill E]

Here you go.

Bill

[sunnyboy010101]

Thank you very much Bill!

-R

On Friday, January 23, 2026 at 5:39:58 PM UTC-8 wjegr...@gmail.com wrote:

Here you go.

Bill

[sunnyboy010101]

I had a post up here since yesterday with a photo of the back of the DB-9 with my labels. I have deleted it as it was INCORRECT.

-R