courtesy of Tomi Engdahl
Port on the Commodore C64
._____________
5 o o o o o / 1
. o o o o /
.9 `~~~~~~~´ 6
1 Up
2 Down
3 Left
4 Right
5 Analog Y
6 Button
7 Power
8 Ground
9 Analog X

Every system has clones right? Well, the Commodore 64 never had any unauthorized clones and still currently doesn't. At least there were none during its official market run. It wasn't cloned until 2002 when Jeri Ellsworth decided to make an enhanced clone of it. Ah, the 20 year old task task just needed a feminine touch. She created the C-One and was later hired by Tulip Computers (who bought Commodore) to create the C64 Direct-to-TV joystick for them. So technically the C-One was the only unauthorized clone, and it was retroactively authorized:)
The C-One is far too brilliant to go into details here. It just needs to be said that it will hardware emulate, or with the addition of real CPUs plugged into the motherboard, become almost any classic 8-bit and some 16-bit computers. Of course its original specifications was as a super Commodore 64 clone.
C64 Direct-to-TV (C64DTV)
Its an entire Commodore 64 contained in its own Joystick plugged into port 2. It runs on four AA batteries with optional external DC power supply. It contains 30 games from EPYX, Hewson, and Image Works. Additionally, some of the games have added content/additional levels. The circuit board is clearly marked so users comfortable with soldering can see where to add a keyboard connector, joystick Port 1 and/or 2, floppy connector, C64 power unit connector!, palette entry reprogramming interface, S-Video, C64 user port and/or PS2 keyboard. Users with more skill can add a parallel, USB, and/or SD/MMC card drive. Additionally it meets System-on-a-Chip specifications despite everything being contained in a motherboard (its a small motherboard). Software modification alone allows for additional games to be added.