update draft post (obsd)

content/notes/openbsd/index.md

@@ -37,6 +37,74 @@ magic	19540119 (FFS2)	time	Thu Nov 16 21:14:34 2023
 This can be helpful if you want to know, which filesystem you actually
 use on your OpenBSD box.
 
+## Create a Win95 FAT32 USB stick
+
+When you `fdisk -iy sd2` (for example) a USB stick, you usually create
+one single OpenBSD partition at the 4<sup>th</sup> position. When you then
+try to `newfs_msdos -F 32 -L Label sd2i` the layout is gone -- happened to
+me several times until I got fed up and investigated.
+
+I don't know why that happened, but I got my way to create USB sticks, that
+actually work with other devices like my amateur radios that need those fancy
+microSD cards.
+
+Delete the first bytes on the stick:
+
+~~~console
+$ doas dd if=/dev/zero bs=1m count=1 of=/dev/rsd2c
+~~~
+
+Create the needed partition:
+
+~~~console
+$ echo -n 'edit 0\n0c\n\n2048\n*\nq\n' | doas fdisk -e sd2
+~~~
+
+A short explanation (`\n` is basically a newline; the <kbd>Enter</kbd> key):
+
+- `edit 0\n`: edit the first entry (`fdisk -iy sd2` would edit the 4th entry)
+- `0c\n`: selects **Win95 FAT32L** as file system format
+- `\n`: only hit enter and use the default _[n]_
+- `2048\n`: Start of the partition
+- `*\n`: Special size value -- means the remainder of the disk (like `-1` on many other tools)
+- `q\n`: write MBR and quits the program
+
+This results in a partition table like this:
+
+~~~console
+$ fdisk sd2
+Disk: sd2	geometry: 966/255/63 [15523840 Sectors]
+Offset: 0	Signature: 0xAA55
+            Starting         Ending         LBA Info:
+ #: id      C   H   S -      C   H   S [       start:        size ]
+-------------------------------------------------------------------------------
+ 0: 0C      0  32  33 -    966  80  10 [        2048:    15521792 ] Win95 FAT32L
+ 1: 00      0   0   0 -      0   0   0 [           0:           0 ] Unused
+ 2: 00      0   0   0 -      0   0   0 [           0:           0 ] Unused
+ 3: 00      0   0   0 -      0   0   0 [           0:           0 ] Unused
+~~~
+
+whereas a `fdisk -iy sd2` creates a table like this:
+
+~~~console
+$ fdisk sd2
+Disk: sd2	geometry: 966/255/63 [15523840 Sectors]
+Offset: 0	Signature: 0xAA55
+            Starting         Ending         LBA Info:
+ #: id      C   H   S -      C   H   S [       start:        size ]
+-------------------------------------------------------------------------------
+ 0: 00      0   0   0 -      0   0   0 [           0:           0 ] Unused
+ 1: 00      0   0   0 -      0   0   0 [           0:           0 ] Unused
+ 2: 00      0   0   0 -      0   0   0 [           0:           0 ] Unused
+*3: A6      0   1   2 -    966  80  10 [          64:    15523776 ] OpenBSD
+~~~
+
+Don't forget to create the file system:
+
+~~~console
+$ doas newfs_msdos -F 32 -L 8GB_Stick sd2i
+~~~
+
 ## Python
 
 ### ModuleNotFoundError