Going way back to 1979 my parents bought us an Atari 2600 for Christmas, back then it was just call Atari. lol We used that thing for many years and I think my brother may still have it.
My first computer was my dads hand me down from 1982, it was an Epson QX10. It had 2 256k floppy disks, a green screen and didn't come with dos, my dad added a dos board later. The computer worked on mbasic and there was no mouse so you had to use commands to do anything. Huge difference from today's computers. lol
If your brother has it then he is sitting on gold, don't let him throw it out!
The first XT PC I used had two floppy drives side by side, and ran DOS. Switching disks to do anything useful was such a pain, and we had to write protect the DOS and software disks to stop folks corrupting them :)