--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sd-card.rst	Mon Mar 11 16:09:03 2024 +0200
@@ -0,0 +1,91 @@
+
+==========
+ SD cards
+==========
+.. contents::
+   :local:
+
+Standards
+=========
+
+======= =========== ====== ======= =============== ==================
+Acronym Capacity    FS     Spec    Compatibility   Name
+======= =========== ====== ======= =============== ==================
+SD      128MB-2GB   FAT16          SD, SDHC, SDXC
+SDHC    4-32 GB     FAT32  SDA 2.0 SDHC, SDXC      High Capacity
+SDXC    64GB-2TB    exFAT  SDA 3.0 SDXC            Extended Capacity
+======= =========== ====== ======= =============== ==================
+
+Ultra High Speed, Phase I (UHS-I):
+* 50MB/s (UHS-50)
+* 104MB/s (UHS-104)
+
+Ultra High Speed Phase II (UHS-II):
+* 156MB/s
+* 312MB/s
+
+Speed
+=====
+
+SD Speed Class (a number inside "C" symbol) write speed:
+
+====== =========
+Class  Min Speed
+====== =========
+2      2MB/s
+4      4MB/s
+6      6MB/s
+8      8MB/s
+10     10MB/s
+====== =========
+
+UHS Speed Class (a number inside "U" symbol) write speed:
+
+====== =========
+Class  Min Speed
+====== =========
+1      10MB/s
+3      30MB/s
+====== =========
+
+Video Speed Class (a number after "V" symbol) write speed:
+
+====== =========
+Class  Min Speed
+====== =========
+6      6MB/s
+10     10MB/s
+30     30MB/s
+60     60MB/s
+90     90MB/s
+====== =========
+
+.. note:: UHS-I bus interface can only support V6 to V30 speed class memory cards. UHS-II is
+          required for V60, V90.
+
+Express Speed Class (a number after "E" symbol) write speed:
+
+====== =========
+Class  Min Speed
+====== =========
+150    150MB/s
+300    300MB/s
+450    450MB/s
+600    600MB/s
+====== =========
+
+Video resolution minimum requirements:
+
+================== ==============
+Video resolution   Speed class
+================== ==============
+640x480   (SD)     C2, C4, U1, V6
+1920x1080 (FullHD) C6, U1, V6
+4k                 C10, U1, V10
+8k                 V60
+================== ==============
+
+https://support-in.wd.com/app/answers/detailweb/a_id/36273/~/specifications-and-compatibility-for-sd%2Fsdhc%2Fsdxc-memory-cards
+  Specifications and Compatibility for SD/SDHC/SDXC Memory Cards.
+https://www.kingston.com/en/blog/personal-storage/memory-card-speed-classes
+  A guide to speed classes for SD and microSD Cards.

--- a/ssh.rst	Sun Feb 11 15:59:42 2024 +0200
+++ b/ssh.rst	Mon Mar 11 16:09:03 2024 +0200
@@ -36,6 +36,7 @@
 Show fingerprint::
 
   ssh-keygen -l -f ~/.ssh/id_dsa
+  ssh-keygen -lvf ~/.ssh/id_dsa
   ssh-keygen -E md5 -l -f ~/.ssh/id_dsa
 
 Change passphrase of priv key::