thanks for the reply. my goal is in fact to take what is at address 0xf0 and store it at 0x400. I know it resembles another beginner error but it’s not this time :)

the example code I’ve given looks pretty contrived but I’ll be using this to write startup code for a microcontroller, and the values starting at src are initial values in flash I need to copy over to dest which is SRAM.

Oh I see, many thanks.

I don’t know what a .map file is, will look into that. This does work, when I objdump it _start is at 0x0. But I’m curious if there is a better solution, I’d like to learn how it’s properly done.

Other than what others have suggested:

• Do get an etch resist pen. The toner occasionally, even when it goes well, might not transfer on some spots of the copper plate. So you’ll need the etch resist marker to color in breaks in paths etc. and fix these little issues.
• The acid or whatever you use to etch away the copper might not work on some spots. Leading to shorts or otherwise unwanted connections. So do check with a multimeter the paths and pads that are close to make sure there arent shorts. You can scratch away unwanted copper with a blade.

I dont think theres much more to add, its quite a simple process. Have fun :)

The toner transfer method would be I think the most DIY method you can use. Make your pcbs entirely by yourself at home.

Naturally wont give you as professional a result: no silkscreen, limited to 2-layer pcbs (2 sides of a copper plate).

But it is a lot faster that having it manufactured (takes me like 1 hour for a pcb) and maybe this is debatable but it makes me feel like I have more room to make mistakes.

Here’s a script I use a lot that creates a temporary directory, cds you into it, then cleans up after you exit. Ctrl-D to exit, and it takes you back to the directory you were in before.

Similar to what another user shared replying to this comment but mine is in bash + does these extra stuff.

#!/bin/bash

function make_temp_dir {
    # create a temporary directory and cd into it.
    TMP_CURR="$PWD";
    TMP_TMPDIR="$(mktemp -d)";
    cd "$TMP_TMPDIR";
}

function del_temp_dir {
    # delete the temporary directory once done using it.
    cd "$TMP_CURR";
    rm -r "$TMP_TMPDIR";
}

function temp {
    # create an empty temp directory and cd into it. Ctr-D to exit, which will
    # delete the temp directory
    make_temp_dir;
    bash -i;
    del_temp_dir;
}

temp