The Amiga computer was around about the same time as the Atari. The two machines and their separate coders were at war to show which computer was the best. The Amiga was very fast and had a unique way to process things that was way faster than the Atari but the Amiga had a slower and more unstable file system which either left you sitting on the floor for over a minute for a good game to load or your disk that worked yesterday has read/write errors today.

The Amiga was definitely  the better games machine but the Atari had faster loading times and had the one advantage over the Amiga - the Atari had a MIDI in and a MIDI out port. this was GREAT for music studios. So much so that the later more powerful Atari's ( Atari Mega STE and such like... ) are still used in some recording studios.

  The problem the Atari ST had was it had a sound card with only 3 channels. (The YM2169 chip) The Amiga had a more advanced card that had 4 channels, sounded better and was a faster decoder so it could handle better sound. This was fixed in later Atari models. The war would probably have continued if Amiga had switched its computers from 7.14MHZ 68000 processors to more powerful ones, such as the 14MHZ 68020 processor a lot earlier. Because of the constant 7.14MHZ Amigas, sales went down and Amiga went under. 

Disk formatting was better on the Amiga than the Atari. On the Amiga, you could format to 880K on DD floppies, and 1760K on HD floppies. The highest I've got on an Atari is 840K per disk. The Atari is faster and more reliable again though. There are some programs on Aminet which claim to get over 1MB on an Amiga floppy, but these I've never tried.  Test them yourself, they're all free.

That is a very nice Amiga setup. its an A500 with an external disk drive, separate speakers for better quality sound, a monitor (hard to come by today) - no yellowing of the case or keys and the guy said he had an extra 512KB RAM upgrade in it - I have all of this except the monitor, but as I have a SCART lead adaptor for my TV, I don't really need one.

Another A500 packed up in its original box. This one didn't have all the upgrades you would want, a 512KB upgrade is highly desirable. You have to keep swapping the disks to copy them when you don't have enough memory. Some games won't run with only 512KB memory too. the best ones needed 1MB so the upgrade was essential. An external disk drive would solve the disk copying problems but not the memory problems, but larger games which needed more memory usually had more than one disk. So to be honest, you need them both to get the best experience.