PiDP-11 build success & IDLED question

[Tom Hunter]

I have successfully built the PiDP-11/70. Like previously with the PiDP-8/I the electronics assembly was simple and it all worked first time.

With both I struggled a bit with the mechanical parts.

The PiDP-8/I front panel was very poorly aligned with the PCB so the bamboo case required some butchering with a Dremel tool. I removed about 2 mm of the right hand side inside the case so that I could shift the PCB further to the right to achieve good alignment between LEDs and switches with the front panel. Annoyingly two of the momentary switches sometimes stick in the de-pressed state. Otherwise it works like a dream.

The PiDP-11/70 front panel holes and the case's threaded holes didn't align and I had to drill the front panel holes larger. The keyswitch hole in the front panel was neither round nor big enough. I carefully drilled it large enough and round. Drilling acrylic panels terrifies me especially if the holes are close to the edges. Luckily in this instance nothing cracked.

While playing with the PiDP-11/70 running the IDLED demo program I halted the program and single stepped a few instructions. When I then toggled HALT up and continued the program by pressing CONT down it wouldn't blink as before. It seemed frozen. After doing a LED test (white momentary switch) and rotating the rotary knob eventually the blinkenlights demo resumed. I am curious why I get the freez-up of IDLED. I don't think this is a SIMH problem, but more likely a feature of IDLED.

Could somebody please point me to the source of the IDLED used with the default PiDP-11/70 software setup?

Also - has anyone else seen this freezing after HALT, STEP, STEP, STEP, ENABLE, CONT.

Thanks and best regards

Tom Hunter

[Neal G.]

Regarding IDLED, look in the related folder of the PiDP systems download (or /opt/pidp11/systems/idled on your Pi). There is a listing and some PDF documentation. I am a little suspicious of its reliability. I have not tried stepping through it; but it seems to freeze after running for long periods of time (12 hours or more). I used to let it run while using Raspian for other tasks through VNC. I switched to leave RSX run instead and do not encounter issues, this is what leads me to think there might be issues with IDLED.

- Neal G.

[Tom Hunter]

Thanks Neal for pointing me to the location of IDLED.

Here are some photos of my new toys:

The front panel of the PiDP-8/I has suffered from my many attempts to get a proper alignment between case, PCB (LEDs & switches) and front panel. I must have removed and fitted it about 50 times until the case allowed proper alignment. The black paint has come off all around the edges of the front panel. The case is not a perfect rectangle but has a somewhat trapezoidal shape.

Cheers

Tom Hunter

[steve...@gmail.com]

Tom,

Re: "The black paint has come off all around the edges of the front panel."

I've had the same thing happen on mine. A reasonable fix seems to be to touch it up with a permanent black felt tip marker like a Sharpie. It's not perfect, but the chips are a lot less noticeable.

-- steve

[jeff.t...@gmail.com]

Hey Oscar - it probably not cost effective, but I be interested in purchasing a new front panel plate for my PiDP-11.  Especially if you find a source that can produce them in the matte finish like the new PiDP-8s have.

[Bill Smith]

The latest PiDP-11/70 kits are shipping with matte front panels. They are a little thinner so you have to install spacers. IIRC they screw onto the bottom of the standoffs before inserting into the front panel to make up for the loss of thickness. Otherwise you can damage the bezel by driving them in to far. And also the PCB will be too far forward and the toggles will stick out too far. 

On Nov 12, 2020, at 12:01 AM, jeff.t...@gmail.com <jeff.t...@gmail.com> wrote:

Hey Oscar - it probably not cost effective, but I be interested in purchasing a new front panel plate for my PiDP-11.  Especially if you find a source that can produce them in the matte finish like the new PiDP-8s have.

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