It has a full featured RS232C port with a standard DB25 connector. Usual DIN video output, with composite video and TTL level Sync. A tape port for Commodore datasetts (there is no tape rutines in the standard C610 kernal) A small cartridge port for expansions. Jack outlet for sound.And a PET type IEEE-488 port.

In the case there is other connectors for co-processor and user expansion.

Let's see the pinouts :

IEEE488           1 1 1 
1 2 3 4 5 6 7 8 9 0 1 2
= = = = = = = = = = = =
### ############# #####
= = = = = = = = = = = = 
A B C D E F H J K L M N
1 - DIO1  9 - IFC  E - REN
2 - DIO2 10 - SRQ  F - GND
3 - DIO3 11 - ATN  H - GND
4 - DIO4 12 - GND  J - GND
5 - EOI   A - DIO5 K - GND
6 - DAV   B - DIO6 L - GND
7 - NRFD  C - DIO7 M - GND
8 - NDAC  D - DIO8 N - GND
RS232C - Same as the well known RS232C ports
connected signals are the following : TXD(2), RXD(3), RTS(4), CTS(5)
DSR(6), GND(7), DCD(8), +5V(11), -12V(12), DTR(20), RXC(24)
Video Connector 
 --u--
/     \     1 - TTL Video
|3   1|     2 - GND
| 5 4 |	    3 - TTL Vsync 
\__2__/	    4 - Composite Video
		   5 - TTL Hsync
Cartridge connector
                  1 1 1 1 1 1
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
= = = = = = = = = = = = = = =
= = = = = = = = = = = = = = = 
A B C D E F G H I J K L M N O 
1 - A0	10 - A9	 D - D3  M - NOT CS BANK1 
2 - A1	11 - A10 E - D4  N - NOT CS BANK2
3 - A2	12 - A11 F - D5  O - NOT CS BANK3
4 - A3  13 - A12 G - D6
5 - A4	14 - +5V H - D7
6 - A5	15 - +5V I - GND
7 - A6   A - D0  J - GND
8 - A7   B - D1  K - R/W
9 - A8   C - D2  L - CLK2