Sviatoslav Chagaev slavc

## how_to_copy_files_to_ms-dos_via_com_port.md

      
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                slavc
                / how_to_copy_files_to_ms-dos_via_com_port.md
            
            
              Created
              October 2, 2025 14:13
            
              
                How to copy files to an MS-DOS computer via COM port from a modern computer
              
          
    Intro

This document describes one specific method of how to copy files to an old computer running MS-DOS from a modern computer running Linux via a COM (Serial) port using a null modem cable.
This is useful if you want to avoid having to use physical media but also don't have a network card for the MS-DOS computer or don't want to use a network card either.
Prerequisites


A USB to RS-232 adapter (e.g. https://amzn.eu/d/eIfenWQ), if your main computer doesn't have a built-in COM (Serial) port.
A null modem cable (e.g.https://amzn.eu/d/d7jq5K8).


## gist:27a2cee21732fc036516d60f34ebcca7
# Sensors

## DHT11 temperature and humidity sensor

1-wire bus protocol, read using https://github.com/szazo/DHT11_Python

## gist:5dadc41854b7c503ca1f6659bf85f5a1
1. Format USB drive using FAT.
2. Copy over all files from the Windows installation DVD, except for `sources/install.wim` - this file is too large to fit on a FAT filesystem.
3. Use https://www.systutorials.com/docs/linux/man/1-wimlib-imagex-split/ tool to split install.wim file into install.swm install2.swm etc.

## vybrid-vf610-tower-bootstrap.txt
# Instructions assume host OS is Fedora Linux.

#
# Clone and build u-boot
#
cd ~/src/
git clone git://git.denx.de/u-boot.git
cd u-boot
sudo dnf install arm-none-eabi-gcc-cs
export ARCH=arm

## Asus C100P Notebook PC boot from SD card
To boot from an SD card on Asus C100P Notebook PC, do the following:

1. Prepare the SD card, e.g. `dd` an OS image onto it and insert it into the notebook.
2. Enable developer mode: turn notebook on while holding Esc+F3(Refresh), after it turns on press Ctrl+D to switch to developer mode.
3. Open a shell (Ctrl+T in Chrome), type `shell` to launch bash, do `sudo crossystem dev_boot_usb=1 dev_boot_signed_only=0`, reboot.
4. At the boot prompt with the developer mode warning, press Ctrl+U to boot from the SD card.

## How to install Fedora Linux onto Wandboard
1. Download a Fedora Linux for ARM image.

2. Install fedora-arm-installer:
    dnf install fedora-arm-installer

3. Write the image to SD card, not forgetting to set the console to serial port:
    fedora-arm-image-installer \
        --image=Fedora-Minimal-armhfp-25-1.3-sda.raw.xz \
        --target=wandboard \
        --media=/dev/sdc \

## How to install an Android toolchain
These instructions describe how to install an Android toolchain capable of compiling standalone C/C++ programs for an Android device.

1. Download Android NDK from https://developer.android.com/ndk/downloads/index.html and unpack it somewhere.

2. Run the included script to install a standalone toolchain:
    mkdir $HOME/opt
    $NDK/build/tools/make-standalone-toolchain.sh --arch=arm --install-dir=$HOME/opt/android_toolchain

3. Create a test program and compile it:
    cat > hello.c << EOF

## after_wakeup.txt
0: Key name.
1: Flags? Keys which have c0 as first byte are usually
   writeable. Second byte seems to be the length of value.
2: Key type.
3: More flags?
4: Value. ``x'' means value could not be read.

0    1        2    3        4
#KEY 88040000 ui32 acb20200 00 00 02 31
$Adr 88040000 ui32 20070020 00 00 03 00
	# Sensors

	## DHT11 temperature and humidity sensor

	1-wire bus protocol, read using https://github.com/szazo/DHT11_Python
	1. Format USB drive using FAT.
	2. Copy over all files from the Windows installation DVD, except for `sources/install.wim` - this file is too large to fit on a FAT filesystem.
	3. Use https://www.systutorials.com/docs/linux/man/1-wimlib-imagex-split/ tool to split install.wim file into install.swm install2.swm etc.
	# Instructions assume host OS is Fedora Linux.

	#
	# Clone and build u-boot
	#
	cd ~/src/
	git clone git://git.denx.de/u-boot.git
	cd u-boot
	sudo dnf install arm-none-eabi-gcc-cs
	export ARCH=arm
	To boot from an SD card on Asus C100P Notebook PC, do the following:

	1. Prepare the SD card, e.g. `dd` an OS image onto it and insert it into the notebook.
	2. Enable developer mode: turn notebook on while holding Esc+F3(Refresh), after it turns on press Ctrl+D to switch to developer mode.
	3. Open a shell (Ctrl+T in Chrome), type `shell` to launch bash, do `sudo crossystem dev_boot_usb=1 dev_boot_signed_only=0`, reboot.
	4. At the boot prompt with the developer mode warning, press Ctrl+U to boot from the SD card.
	1. Download a Fedora Linux for ARM image.

	2. Install fedora-arm-installer:
	dnf install fedora-arm-installer

	3. Write the image to SD card, not forgetting to set the console to serial port:
	fedora-arm-image-installer \
	--image=Fedora-Minimal-armhfp-25-1.3-sda.raw.xz \
	--target=wandboard \
	--media=/dev/sdc \
	These instructions describe how to install an Android toolchain capable of compiling standalone C/C++ programs for an Android device.

	1. Download Android NDK from https://developer.android.com/ndk/downloads/index.html and unpack it somewhere.

	2. Run the included script to install a standalone toolchain:
	mkdir $HOME/opt
	$NDK/build/tools/make-standalone-toolchain.sh --arch=arm --install-dir=$HOME/opt/android_toolchain

	3. Create a test program and compile it:
	cat > hello.c << EOF
	0: Key name.
	1: Flags? Keys which have c0 as first byte are usually
	writeable. Second byte seems to be the length of value.
	2: Key type.
	3: More flags?
	4: Value. ``x'' means value could not be read.

	0 1 2 3 4
	#KEY 88040000 ui32 acb20200 00 00 02 31
	$Adr 88040000 ui32 20070020 00 00 03 00