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Fix HP 48G, 48GX, 48SX power on failure

After switching the 3 AAA batteries of my beloved HP 48G calculator, it didn’t turn on anymore when hitting the “ON” button in the bottom left corner. I first thought it’s because of poor electrical contact due to poor QA batteries (I noticed the new ones were a fraction of a mm shorter than the previous ones). This might have played a rule in the sudden failure to power on my HP 48G, but it probably wasn’t the only reason.

Here are some “tricks” to try, if your HP 48 won’t turn on:

  1. Double-check that you inserted the AAA batteries pointing with their (+) poles in the right direction (left, right, left)
  2. If the AAA batteries have poor electric contact (particularly the middle one is susceptible to this), cut out and fold some aluminium foil (also called “aluminum foil”; historically “tin foil” was used), and put it where better electric contact to the batteries is needed.
  3. Press the “ON” button in the bottom left corner
  4. If that doesn’t work: press and hold “ON”, press and release the “C” button, release the “ON” button
  5. If that doesn’t work (it didn’t for me): Press the area between the “B” and “C” buttons/keys, then press and release “ON”
  6. If that still doesn’t work (it didn’t for me): Flip the HP 48 over and remove the upper right rubber foot. You can basically just wiggle it a bit and pop it off, there’s no need for special instruments. Underneath, there’s a little hole to reset the calculator. Use e.g. a paperclip, insert one end into the hole until you hear or feel a subtle “click” sound to reset the calculator (please bear in mind that this could also clear the memory).
    Then press the “ON” button and you’ll be prompted to try recovering the memory, which you should confirm.
  7. At this point, unless it’s a severe error of the board, your HP 48 should turn on again.
    It might display “Warning: Invalid Card Data” at every start though. You can get rid of this warning message by typing “PINIT” (without double quotes) and pressing the ENTER button (source: https://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv013.cgi?read=43990)

If none of the above tips help, your HP 48 probably needs repairing.

It seems to be quite a nightmare to service the HP 48, but there are a couple of videos out there of people repairing a HP 48 SX (disclaimer: know what you’re doing, follow at your own risk):

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Nomad Network – Communicate Freely

Off-grid, resilient mesh communication with strong encryption, forward secrecy and extreme privacy.

Nomad Network allows you to build private and resilient communications platforms that are in complete control and ownership of the people that use them. No signups, no agreements, no handover of any data, no permissions and gatekeepers.

https://github.com/markqvist/NomadNet

Information is the basis of society in the digital world.
Freedom of expression/speech and free access to information are indispensable prerequisites for democracy.

Sadly, there are misleading and dubious organisations, lobbyists, parties, secret services, legislative and executive bodies that work against these liberal, enlightened and humanitarian values and demand or advocate censorship, online and offline.
This is a big threat for civil society – you and me, all of us.

And this is what makes projects like NomadNet important and valuable.

Stand up for freedom of expression/free speech and fight censorship!

(And as always, please note the disclaimer: All software and hardware can have security bugs).

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Browser add-ons to skip sponsor segments and prevent clickbait on YouTube

Two pretty interesting browser add-ons/plugins to improve the UX on YouTube:

SponsorBlock is an open-source crowdsourced browser extension and open API for skipping sponsor segments in YouTube videos. Users submit when a sponsor happens from the extension, and the extension automatically skips sponsors it knows about using a privacy preserving query system. It also supports skipping other categories, such as intros, outros and reminders to subscribe, and skipping to the point with highlight.

DeArrow is an open source browser extension for crowdsourcing better titles and thumbnails on YouTube. The goal is to make titles accurate and reduce sensationalism. No more arrows, ridiculous faces, and no more clickbait.

(/ht https://news.ycombinator.com/item?id=41222577)

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How to determine/find out whether your Mac/macOS is in Safe Mode?

  1. In the Apple menu, click on “About This Mac”
  2. Then click on the “More info…” button
  3. Click on the “System Report…” button
  4. In the appearing System Report window, click on the “Software” menu item in the left pane
  5. In the right pane, look for “Boot Mode:”. It should be “Safe”.

(I recently noticed that it’s quite difficult to distinguish whether your Mac has really been booted in “Safe Mode”, as visually, there doesn’t seem to be much of difference anymore to how the desktop looks in regular mode)

And BTW, to boot a Mac with Apple Silicon in Safe Mode:

  1. Shut your Mac/macOS down
  2. To boot it again, press the power button and hold it
  3. Select the volume to boot (i.e. click on the volume icon)
  4. Hit and hold the shift key
  5. Click on the appearing text (“Continue in Safe Mode” or so) below the volume icon
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Zimbra ZCS: How to export and import e-mail messages using the CLI

I verified the tips on the page below. The only mistake I’ve noticed is that the date format is wrongly indicated, i.e. instead of in MM/DD/YYYY format, the dates have to be specified in DD/MM/YYYY format.

So, the 1) command should be:

$ zmmailbox -z -m alice@example.com gru "//?fmt=tgz&query=after:"20/07/2022"&before:"26/07/2022"" >> /tmp/alice.tgz

https://wiki.zimbra.com/wiki/How_to_export_import_emails_for_a_specific_date

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macOS Ventura: Fix the “Operation not permitted” error in Terminal

The “Operation not permitted” error message is caused by one of the typical annoyancesfeatures in macOS, namely the Terminal app lacking “full disk access” by default (and by design).

This conclusion unfortunately isn’t obvious, as when encountering the above error message, one would typically first check the ownerships and permissions of the directory/file/symlink “causing” the error, then perhaps the ACL / extended attributes, then whether the resource might still be locked by another process accessing it, and last but not least, one would remember macOS’s SIP (System Integrity Protection) and even consider booting into recovery mode. But none of that is actually required. The solution is:

  1. In the macOS “System Settings”, go to “Privacy & Security”
  2. Then click on “Full Disk Access” and enable it for “Terminal” (slider turns blue)
  3. Open a new Terminal window/session

Irritatingly, upgrading to macOS Ventura apparently resets the Terminal app’s security privileges.

Example:

I wanted to remove and recreate a symlink, so that “MobileSync” (where macOS stores backups of iOS devices like iPhones, iPads) isn’t just a regular, local directory, but a symlink pointing to a directory on a mounted NAS share. Advantage: Backups of iOS devices don’t use up valuable (and expensive) SSD storage space on your MacBook Air/Pro, but use cheap NAS storage instead (further, you don’t create duplicate backups on each of your Macs). Here’s where the MobileSync symlink is located and where it points to, in my case (you can create it using ‘ln -s /Volumes/backups_ios/MobileSync .‘, my share is named ‘backup_ios‘)

mymac ~/Library/Application Support $ ls -lad ~/Library/Application\ Support/MobileSync
lrwxr-xr-x 1 myuser staff 31 Apr  1 00:47 '/Users/myuser/Library/Application Support/MobileSync' -> /Volumes/backups_ios/MobileSync

Even as root, I first couldn’t remove the symlink I created some time back before the upgrade to Ventura. Which is even the more puzzling considering this all happens in a regular user’s home directory.