Computer Log

Yesterday this company named The Pi Hut tweeted that they’d have Raspberry Pi 4 Model B 4GB today at 9PM UK time. So I set my alarm to remind me, fully not expecting to get one…but I did. I totally did something out of character…pay for shipping. Which is over $20 from there. Normally I’d just wait for them to be available here in the US then order through Amazon with free shipping.

Raspberry Pi 4 Model B 4GB £52.08 (about $64.84 US)
Subtotal £52.08

Shipping £20.00

Taxes £0.00
Total £72.08 GBP

So $90.10 US…still $55 cheaper than Amazon!

I also ordered the official power supply from Amazon.

A nice upgrade, for me…

• 4GB memory…8 times more than my Pi B+
• 4 cores…3 more
• 64 bit (although for the PiDP-11 software, you need a 32 bit OS)
• Twice as fast
• USB 3
• Bluetooth
• Wi-Fi built in

Good thing I watched a video. Found out HDMI is micro. So I’ll need a Micro-HDMI to HDMI Cable.

In one video that I watched the guy said…you can “even” use Linux to install the OS. So besides those advanced OSs such as Windows and Mac…it’s pretty cool that I can use Linux to install Linux.

This is my second Pi and my first since 2014…9 years ago.

I don’t know if I ever documented this or not. But back in college we had a PDP-11/40 (or maybe 45). Some courses required a computer credit. The main computer courses were on the IBM mainframe. That probably would have been a steep introduction to computers. Programs were punched to cards, then read by a card reader. But the PDP-11/40 ran RSTS/E and you used Basic-Plus to program it. The programs were coded interactively on a terminal. So it was a fairly popular course for…computer and non computer people.

Hence, there were long lines of people waiting to get a terminal. The department hired student/tutors to check people in on a terminal and they would have 30 min before these “monitors” would tell them their time was up. Eventually I got a job as a tutor/monitor. I would shut the 11/40 down at night and lock up the room. I would also boot it up on the weekends. I had full access to the computer and manuals, regular students didn’t have access to and the mighty 1,2 account. Having access to 1,2 was like having access to root on Linux. So I learned much more about RSTS…than most.

After learning about SYS calls, I had an idea to write a automated student monitor program. I remember working on it one day when my teacher/boss walked in and asked me what I was doing. Nervously, I told him. Surprisingly he didn’t seem angry…supportive even. So my program would log into a table when a user would sign on, and at 25 minutes would send them a message and beeps that they had 5 minutes to finish up. I would continue sending a message each minute until 30 minutes then log or force them off. Keeping a record so they couldn’t just log right back on. This reduced the need for tutors to manually monitor people. I was pretty proud of that simple little program, all those years ago.

I was very fortunate to have a teacher/boss who trusted me…a student, enough to do this. Thank you Mr. Walton (wherever you are).

The PiDP-11 manual has instructions for running the software without the front panel. However starting RSTS/E took almost an hour. So I posted the problem on the PiDP-11 google group. Oscar suggested commenting out starting the server startup in /opt/pidp11/bin/pidp11.sh Here is a part of the script with the server commented out

    echo "*** Start client/server ***"
#       sudo ./server11 &
    sleep 2
    sudo ./client11 /run/pidp11/tmpsimhcommand.txt

    # after simh exits, check if a newly created command file now says exit>
    if [[ $(< /run/pidp11/tmpsimhcommand.txt) == "exit" ]]; then
            reboot=1
    else
            reboot=0
    fi

    ((reboot==1))

This. made a huge difference. Before I got a “CPU is too slow” message

After commenting out the server…I still got the “CPU is too slow” message . However it was much closer to the 1M target. And starting RSTS/E went from almost an hour to less than a minute.

I always wondered why smh pegged the CPU. But as I was reading about FOCAL-69 on the PiDP-8 they showed a command set cpu idle. There were other interesting commands. See PDP-8 on simh below.

Anywho I added it to my RSTS/E games.ini and no more pegged CPU.

I stumbled upon this demo today. It was interesting because it shows how the PiDP-11 software reacts to the panel switches. At around the 4:55 min mark.

Nothing technical on my part. I just copied and ran this. From these instructions. FOCAL-69 from paper tape image. Still…as a fan of DEC…cool to see this.

$ pdp8

PDP-8 simulator V3.8-1
sim> load focal69.bin
sim> run 200
_TYPE “HELLO, WORLD”
HELLO, WORLD*

As mentioned from those instructions, several software kits available to run on the PDP-8 and documentation for these can be found on the Simulator Documentation page.

There are also other OSs for the PDP-10 and PDP-11.

Official…here!

So I have this crazy idea to build a PiDP-11/70 front panel…kit. But I’ve never soldered before. And that makes me nervous. If I could buy it built…I would. So I was looking for something cheap to practice on and found this (only $6)…

Which like the PiDP-11/70 has a lot of LEDs (but not as many).

So I ordered it and when it came…all I saw (so I thought) was the battery pack.
Great now I need to contact Amazon to tell them they forgot part of my order.

However the description on the other side said kit. And when I opened it, I found…this

No instructions, however that very clear pic is probably all I’ll need. As you can see the board in the picture looks like it would take 16 battery packs to cover that board.

So now I know I’m going to need something like this…

Oh yeah…I haven’t even bought a soldering iron yet!

Found out about this new (to me anyway) video community based on peertube. Read about it here. He says… it’s part of the Fediverse (so you can follow a channel on Peertube straight from Mastodon for example). Sounds interesting.