I need to install r300_cp.bin (graphics driver) from the console as the root user on a DELL Inspiron 9300 (in beautiful condition). I am new to Linux but very willing to learn. The most recent post related to this broader topic was in Nov. 2019, but it offered no help as to my specific problem.
I performed the full "Buster" install using the firmware-10.2.0-i386-DVD.iso package from Debian. That distro included the wi-fi/ethernet drivers, but not the graphics driver. It is tricky with display startup software as you have to use the very screen that you are trying to load a driver for. I have a second (satellite) display connected, via the VGA port, to the computer as the console display for now.
I need line-by-line command console commands for this, I believe, and to know when to reboot for completion of the process. My eyesight is poor and the small characters are rather blurred. I have already downloaded the driver file onto a usb memory stick. Thanks!

Sorry I don't have step by step instructions, but https://wiki.debian.org/AtiHowTo should come close. Although that page doesn't specifically mention Debian 10 a.k.a. Buster, the process is likely to be the same. According to https://wiki.debian.org/Firmware, your driver seems to be radeon.ko.

Plenty of other resources on the internet.

Thanks! This reminds me of being in a French class. The substitute teacher held up a book and said, "Qu'est que c'est?" Yeah, right, WTF -- I switched to analytic geometry as an homage to René Descartes. Oh well, who needs a GUI anyway? :-)

Fun with Debian is greatly reduced if you omit the command line.

When Buster will not load from a DVD (genuine Debian) nor from a (new) Network Install CD, but Jessie will install (as always) from an old Network CD, is this merely a conundrum? Buster likes my DELL, too, but not my HP. :-(