I read the following:

1. Automatic transmission uses torque converter and planetary gears, while manual transmission uses clutch and a gear box.
2. In automatic transmission, computer and hydraulics decide when and how to change gears.

What I don't understand is the connection between the two. Why, for example, manual transmission doesn't use torque converter or planetary gears?

I read the following:

1. Automatic transmission uses a torque converter and planetary gears, while manual transmission uses a clutch and a gear box.
2. In an automatic transmission, the computer and hydraulics decide when and how to change gears.

What I don't understand is the connection between the two. Why, for example, doesn't manual transmission use a torque converter or planetary gears?