System Expandability And Adaptability - Commodore Amiga Hardware Reference Manual

For those who prefer incremental cursor control, there are cursor keys on the keyboard.
You can attach many other types of controllers through the two controller ports on the
side of the base unit. You can use a mouse, joystick, keypad, trackball, or steering
wheel controller in either of the controller ports. (A light pen can be attached to port 0.)
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I
System Expandability and Adaptability
You can add peripheral devices to the Amiga's expansion connector, add additional
external RAM on the same expansion connector, or upgrade internal RAM to 512K.
Additional disk units may be daisy-chained from a connector at the rear of the unit for a
total of three extra drives.
The system software is highly adaptable to other host operating systems. The Amiga's
graphics support routines are designed to make the user interface as friendly as possible.
New peripheral devices are recognized and used by system software through a well-
defined, well-documented linking procedure.
6 Introduction