There are a lot of old develop boards for all kinds for cpu’s.
These where build to learn machine code programming. Mostly made in the 80’s, and based on populair cpu’s at that time.
I own a some of these SDK’s (System Design Kits)
Most of these use a keyboard scanner which is also connected to 7 segment displays.
The way they work is practically the same. There is a VIA or PIA. Versitile interface adaptor, or Peripheral interface adaptor. These have two times 8 bits to control devices. When using 4 bits and convert these to 16 lines by using a 75ls145 for example. If you put a counter on those 4 bits, you sequently activate 1 of 16 lines. These lines you can use to scan a keyboard matrix OR display a character on a 7 segment display. These display’s won’t hold the data (and show the character) when not activated. The trick is to update de display fast enough so you don’t see the flickering on/off.
Activate a line and read a byte with the VIA = Reading keyboard row Activate a line and write a byte with the VIA = Display on a segment
These VIA/PIA’s where made with specific timings to match the CPU. 6522/6820/8255
Below you see some different implementations of these keyboard/display combo’s
When looking at the 8085 version you see transistors being a ULN2003 is a chip with those transistors/amplification enclosed. It doesn´t draw much current from the bus, and diodes protect the way the current flows.
Februari 2021 i made a website to view images and movies in a browser to do some quick sorting. (borrowed some code from a codepen page i recall correctly) At the time i didn´t have a good way to view webp webm media. I wanted to view multiple files at the same time, and make it short and simple.
BTW no webserver needed, just open the file from a directory! jpg’s png’s webm webp mp4 svg and animated gifs work. (maybe more, didn’t test more, whatever your browser supports)
With recent updates of the chrome browser the video attributes to mute is broken, i so made a workaround. Also everything is in one file now. Except for one issue .. i couldn´t create one file for images AND videos.
There is a piece of javascript i could not fix … yet I have to do execute a document.createElement which is different for images and videos. Also the attributes of video are mute,autoplay,loop,playinline
We bought some servers a while ago, but these have old ILO versions (2).
To manage these servers via ILO was no problem until modern browsers refuse to connect to these web services, because of TLS 1.0 issues.
So what i did was using a second user account on my workstation with a old (downloaded from a ESR archive) version firefox. To administer the ILO
wget https://ftp.mozilla.org/pub/firefox/releases/50.0/linux-x86_64/en-US/firefox-50.0.tar.bz2
extract in other users homedir
usage:
# ssh with X forwarding and start old version
ssh -X otheruser@localhost firefox/oldfirefox
While this was working for me on a debian based machine it didn’t work for my friend who was using Fedora on Wayland.
So i made a more generic solution which would work always. Also when working from windows.
I downloaded a old Fedora version ISO. https://archives.fedoraproject.org/pub/archive/fedora/linux/releases/15/Fedora/x86_64/iso/ Using the DVD iso i knew the old JAVA was present.
So i started virt-manager and created a new virtual machine
Select your downloaded Fedora 15 ISO
Create a disk image for the OS, don’t worry about the size we are going to shrink it to a minimum (thin provisioned)
Disable all thats not needed! .. Only Gnome Graphical internet .. and JAVA
Create users, complete the install and reboot. Test your installation. Shutdown
sudo qemu-img info /var/lib/libvirt/images/fedora15.qcow2 When above gives you a RAW image, you need to convert from RAW to QCOW first. Mine showed a 9G qcow2 image .. far to large
I had a crash recently on one of my raspberry-pi’s .. SDcard failure, they are not made for a lot of write actions. In the past i’ve changed some images to read only and with a r/w overlay. Also tmp filesystems in memory .. all not ideal.
So i’ve started to make every RPi ssd bootable.
I’ve got several ssd already from other projects. Sata to USB adaptors are cheap, only a few euro’s.
Steps to take:
Download Raspberry Pi Imager tool
Choose OS > Misc Utility Images > Bootloader > USB Boot
Select storage and write to a temporary sd-card (Not needed any more after flashing for normal operations)
Boot USB with this Micro-SDcard .. i didn’t have a screen connected .. So i just waited a few minutes
While i was waiting i wrote a OS image to the SSD using the same imager tool
Choose OS > select sata/ssd drive
Change options (cog), enable ssh, choose hostname and set password
Write to drive
Remove sdcard from RPi attach ssd/sata and boot
So .. without attaching a screen or keyboard, just a network cable. I have a running OS on a RPi from SSD
Last year i made a script for a friend who wanted to detect visually if his garden sprinkler was on or off. A few days ago i saw someone who wanted to see if things where moving in his house. (didn’t trust his landlord i think) But he only had a dumb/simple/cheap camera .. so it had no motion detection.
I was thinking of my script, and could easily adapt it for this usage.
Most ipcams have somekind of URL/API you can use to capture a image. Some examples below
So using below script i can capture a image, compare it to the previous, and when it’s above a certain threshold sends a email.
#!/bin/bash
# Only uses wget and image-magick
treshhold=500
fuzzyness=20%
# CHANGE WEBCAM THINGY TO OWN URL AND CREDENTIALS
wget -q "http://webcamip/cgi-bin/api.cgi?cmd=Snap&channel=0&user=user&password=password" -O previous.jpg
while true; do
wget -q "http://webcamip/cgi-bin/api.cgi?cmd=Snap&channel=0&user=user&password=password" -O current.jpg
value=$(compare -fuzz $fuzzyness previous.jpg current.jpg -metric mae diff.jpg 2>&1 | cut -f1 -d.)
if [ $value -gt $treshhold ] ; then
echo "ping $treshhold"
echo "Something moved" | mail -s "Movement" user@example.com -A diff.jpg
fi
# Comment below if you want to compare against a base line .. not previous image
cat current.jpg > previous.jpg
sleep 60
done
Example previous picture
Example current picture
I got mailed with result
Hints tips:
Use crop to detect only a part.
copy current.jpg to a second file
Use painting black a part and compair with different treshhold fuzzyness to get different hotspots.
Below detects RED, use above ide with crop to detect red/green/blue leds
compare -verbose -metric mae 1.jpg 2.jpg /tmp/1.diff
1.jpg JPEG 2560x1920 2560x1920+0+0 8-bit sRGB 248819B 0.050u 0:00.057
2.jpg JPEG 2560x1920 2560x1920+0+0 8-bit sRGB 248949B 0.030u 0:00.137
Image: 1.jpg
Channel distortion: MAE
Channel distortion: MAE
red: 12517.5 (0.191005)
green: 11967.1 (0.182607)
blue: 12492.8 (0.190628)
all: 12325.8 (0.18808)
1.jpg=>/tmp/1.diff JPEG 2560x1920 2560x1920+0+0 8-bit sRGB 1.19495MiB 1.470u 0:00.197
The goal of this project is to have a raspberry-pi with a screen wich shows network information. It wil be using a battery, touchscreen .. maybe some status leds. When debugging network issues we want to have information when/if/how a network port works on our switches.
It should show:
dhcp ip
gateway
can access internet?
speedtest
detect if vlan tagged network packets are present on the port?
icmp test
list of detected nearby hosts?
A long time ago i played with glade and C / Perl.
But i’d rather use python so i’m looking into glade/python combi for this little project.
Glade is a gnome/GTK user interface RAD tool. (Rapid Application Development)
i’ve used zenity and yad before to create simple gui’s for bash scripts, these where only for quick and dirty solutions. (See other posts) Glade is a far better solution, but a little harder to use.
Below is a little framework i started with
Python script
import gi
gi.require_version("Gtk", "3.0")
from gi.repository import Gtk
class Handler:
def onDestroy(self, *args):
Gtk.main_quit()
def on_firstbutton_clicked(self, button):
print("Ping test")
builder = Gtk.Builder()
builder.add_from_file("mytest.glade")
builder.connect_signals(Handler())
window = builder.get_object("Main")
window.show_all()
Gtk.main()
Found these old .. old mini-cassettes .. wish i could read these now. The sdk units we had, had tapedrives and few other hardware devices you could play with. Like a motor you could control, which had a disc with slots in it on top. These slots could be read and counted with a sensor to determine the speed.
Also this scanned pages, from school i found. There should also be a little notbook with programs and notes ..