How to offline install WiFi b43 driver on the Dell Inspiron 1520

gistfile1.txt

http://askubuntu.com/questions/730799/installing-fimware-b43-installer-offline

You need to install firmware-b43-installer.

If you do not have an alternative internet connection, do it this way.

If you installed bcmwl-kernel-source, then remove it.

    sudo apt-get purge bcmwl-kernel-source
Download these files
http://mirrors.kernel.org/ubuntu/pool/main/b/b43-fwcutter/b43-fwcutter_015-9_amd64.deb http://www.lwfinger.com/b43-firmware/broadcom-wl-5.100.138.tar.bz2

Copy them to your Ubuntu Home folder.
Run in terminal
sudo dpkg -i b43-fwcutter_015-9_amd64.deb
tar xfvj broadcom-wl-5.100.138.tar.bz2
sudo b43-fwcutter -w /lib/firmware broadcom-wl-5.100.138/linux/wl_apsta.o
Reboot or run:
sudo modprobe b43
Note: For 32-bit systems download http://mirrors.kernel.org/ubuntu/pool/main/b/b43-fwcutter/b43-fwcutter_015-9_i386.deb instead of amd64 and update the file name in the dpkg command.

For Ubuntu 16.04 http://mirrors.kernel.org/ubuntu/pool/main/b/b43-fwcutter/b43-fwcutter_019-2_amd64.deb should be installed or the i386 alternative.