RPi 3 Model A+ ?

[Jeff Crilly]

I just got done building a PiDP-8 over the Xmas break, and have PiDP-11 I’m looking to build soon.
Both of these have been sitting on my shelf in the shipping box waiting for some free time. Now that I’ve finished the 8 , I’m itching to build the 11.

Finding a Raspberry Pi though is (as I’m sure you all know) either difficult or expensive.
Luckily, I had a Pi 3 model B laying around which I put in the PiDP-8. However, after digging through my Pi collection it seems I do not have another Pi 2 or 3. Just a Pi 1 Model B+, and a Pi 4/8GB.
The Pi 4 8GB seems overkill for the PiDP-11.

I’m wondering if a Pi 3 Model A+ will work. Any problems with this?
E.g. I see the PiDP-11 board is silkscreened for a Model B .. will the Model A+ also mount to the existing holes?
Afaict the only effective difference with the A+ is 512MB memory vs 1GB on the Pi 3 Model B+ ; I’m assuming SIMH works fine in 512MB.

Thx for any suggestions.

-Jeff

[Warren Young]

On Jan 2, 2023, at 00:34, Jeff Crilly <jeffc...@gmail.com> wrote:

I had a Pi 3 model B laying around which I put in the PiDP-8.

That’s a good choice, since it lets you use the ILS.  More power is overkill, IMO, and there’s a niggling compatibility problem remaining with the Pi 4 anyway, since none of the committers apparently have a 4 to sort the matter out with.

(We’ve got a few branches with proposed fixes, and more on the mailing list, but no one’s got the clout to say, “This is the one.”)

The Pi 4 8GB seems overkill for the PiDP-11.  

I’d do that anyway, then park other services in the background to soak up the untapped power. It’d be a shame for your -11 to be *less* powerful than your -8!

I used to do that with my PiDP-8/I, in fact, since even with the ILS, it left about 2.5 cores worth of power unused.

There are lots of ways to soak that extra power up:

• VPN termination point; I suggest WireGuard over something horrid like IPSec, obsolete like PPTP, or with bad initial design decisions (TCP transport) like OpenVPN.
• AdGuard/PiHole ad-blocking DNS proxy
• Home automation controller
• LibreNMS monitoring host
• Docker container host. There are lots and lots of trustworthy containers precompiled for ARM64, and getting more is easy. Allow me to plug my own tiny Fossil server container as one example. If you like the way the PiDP-8/I software project site works, you can set that up in the background on either the -8 or the -11, no problem; having it containerized is a fine option, isolating it from the host for better security.

[Jeff Crilly]

I just got done building a PiDP-8 over the Xmas break, and have PiDP-11 I’m looking to build soon.
Both of these have been sitting on my shelf in the shipping box waiting for some free time. Now that I’ve finished the 8 , I’m itching to build the 11.

Finding a Raspberry Pi though is (as I’m sure you all know) either difficult or expensive.
Luckily, I had a Pi 3 model B laying around which I put in the PiDP-8. However, after digging through my Pi collection it seems I do not have another Pi 2 or 3. Just a Pi 1 Model B+, and a Pi 4/8GB.

The Pi 4 8GB seems overkill for the PiDP-11.

[steve...@gmail.com]

Jeff,

From Oscar's PiDP-8/I web site:

"Compatible with the Raspberry Pi 4, 3, 2, B+, A+, Zero W & Zero"

And from the PiDP-11/70 web site:

"Compatible with the Pi 4, 3, 2, B+, A+, and Zero (W)Recommended: Pi 4, 3 or 2."

"I’m wondering if a Pi 3 Model A+ will work. Any problems with this?  

E.g. I see the PiDP-11 board is silkscreened for a Model B .. will the Model A+ also mount to the existing holes?"

From what I can tell the A+ board is a bit shorter (in the direction of the GPIO pins) than the 2, 3, and 4. It will mount into the GPIO header but only the mounting screws on the uSD card side of the Pi will match. The mounting holes on the USB connector side of the Pi won't match. On the other hand, that really shouldn't matter in the long run.

If CPU capacity/load is a concern, another thing that can significantly reduce load is to run SIMH throttled to realistic speeds. I guess I've always been more of a retro-purist and think if you're going to run retro systems they ought to run at realistic speeds, too. When throttled realistically, both the -8/I and the -11/70 use only about 10-20% of the CPU capacity on a 3B or 3B+. In that case, it really shouldn't matter much which Pi you use in which PiDP.

Cheers,

-- steve

[oscarv]

The Pi 3A+ will work fine, I am sure. The screw mounts next to the GPIO will fit for sure, and that is sufficient.

Kind regards,

Oscar.

[David Rosengrant]

I'm going to use the 3A+ for both the pdp8 and 11/70. You can mount it to the pcb, there are screw holes for it.

Dave R

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[Mike Katz]

I'm running my PiDP/8I on a 3B and my PiDP-11/70 with a 4B and an SSD via USB3.0.

To view this discussion on the web visit https://groups.google.com/d/msgid/pidp-11/CAG890Ute1V4zYMFh5KGZ-2ZcjOZF9ntyUrj%2BuUVfEyOBwA8tUg%40mail.gmail.com.