BCM43142 & BCM43142A0 & Debian

If you have a computer with a BCM43142 wifi card like my Lenovo S20, you can get it working by using the broadcom-sta-dkms (https://packages.debian.org/buster/broadcom-sta-dkms) package from Debian's non-free repository.  

02:00.0 Network controller: Broadcom Inc. and subsidiaries BCM43142 802.11b/g/n (rev 01)

Also, BCM43142A0 can be enabled by using the package firmware-b43-installer (https://wiki.debian.org/bcm43xx)