VIC-20 Ports and Pinouts

9 pin D-sub male (D9M) at the computer.

Source: VIC-20 User Manual

 

44 pin female edge at the computer. The pins function as described below:

Pin

Name

Description Pin

Name

Description
1 GND System ground A GND System ground
2 CD0 Data bus bit 0 B CA0 Address bus bit 0
3 CD1 Data bus bit 1 C CA1 Address bus bit 1
4 CD2 Data bus bit 2 D CA2 Address bus bit 2
5 CD3 Data bus bit 3 E CA3 Address bus bit 3
6 CD4 Data bus bit 4 F CA4 Address bus bit 4
7 CD5 Data bus bit 5 H CA5 Address bus bit 5
8 CD6 Data bus bit 6 J CA6 Address bus bit 6
9 CD7 Data bus bit 7 K CA7 Address bus bit 7
10 /BLK1 8K decoded RAM/ROM block 1 ($2000 - $3FFF) L CA8 Address bus bit 8
11 /BLK2 8K decoded RAM/ROM block 2 ($4000 - $5FFF) M CA9 Address bus bit 9
12 /BLK3 8K decoded RAM/ROM block 3 ($6000 - $7FFF) N CA10 Address bus bit 10
13 /BLK5 8K decoded RAM/ROM block 5 ($A000 - $BFFF) P CA11 Address bus bit 11
14 /RAM1 1K decoded RAM block ($0400 - $07FF) R CA12 Address bus bit 12
15 /RAM2 1K decoded RAM block ($0800 - $0BFF) S CA13 Address bus bit 13
16 /RAM3 1K decoded RAM block ($0C00 - $0FFF) T /I/O2 I/O block 2 (located at $9600)
17 VR/W Read/Write line from VIC chip (high-read, low-write) U /I/O3 I/O block 3 (located at $9C00)
18 CR/W Read/Write line from CPU (high-read, low-write) V S02 Phase 2 System Clock
19 /IRQ Interrupt request line to 6502 W /NMI 6502 Non maskable interrupt
20 n/c Not connected X /RESET 6502 Reset pin
21 +5V +5 VDC Y n/c Not connected
22 GND System ground Z GND System ground

Source: VIC-20 User Manual, VIC-20 Programmer's Reference Guide

 

 

 

5 pin DIN 180� (DIN 41524) female at the computer.

Notice that the video output is on two pins. They are the same (wired together inside the computer) on some versions, and output a slightly different signal level in others. Use pin 4 for interfacing a video monitor such as the 1702 and pin 2 for the shield (ground).

Note: The prewired CBM cable should be the two wire type. A three wire cable used for Y/C video (C64 or C128) will not work.

Note: Be careful of the +6 volt line! It's there to source power to the -external- RF modulator used with the VIC20.

Source: VIC-20 User Manual, Ray Carlsen's C= Repair Articles

 

6 pin DIN (DIN 45322) female at the computer.

1 SERIAL
SRQ IN
Serial service request in: Any device on the serial bus can bring this signal low when it requires attention from the VIC. The VIC will then take care of the device.
2 GND Ground
3 SERIAL ATN
IN/OUT
Serial attention in/out: The VIC uses this signal to start a command sequence for a device on the serial bus. When the VIC brings this signal low, all other devices on the bus start listening for the VIC to transmit an address. The device addressed must respond in a preset period of time; otherwise the VIC will assume that the device addressed is not on the bus, and will return an error in the status word.
4 SERIAL CLK
IN/OUT
Serial clock in/out: This signal is used for timing on the serial bus.
5 SERIAL DATA
IN/OUT
Serial data in/out: Data on the serial bus is transmitted one bit at a time on this line.
6 NO
CONNECTION
Note: in some models pin 6 is /RESET

Source: VIC-20 User Manual, VIC-20 Programmer's Reference Guide

 

6 pin male edge at the computer.

Source: VIC-20 User Manual

 

24 pin male edge (DZM 12 DREH) at the computer.

Note: pin 2 is +5VDC, pins 10 and 11 are +9VAC

Upper side
1 GND Ground
2 +5VDC 100mA max
3 /RESET By grounding this pin, the VIC will do a cold start, resetting completely and erasing any program in memory.
4 JOY0 This pin is connected to joystick switch 0 (See game port).
5 JOY1 (See game port.)
6 JOY2 (See game port.)
7 LIGHT
PEN
This pin also acts ad the input for the joystick fire button (See game port).
8 CASSETTE
SWITCH
This pin is connected to the sense cassette switch line.
9 SERIAL
ATN IN
This pin is connected to the ATN IN line of the serial bus.
10 9VAC (+ phase) Connected directly to the VIC transformer.
11 9VAC (- phase) Connected directly to the VIC transformer.
12 GND Ground
Bottom side
A GND Ground
B CB1 The VIC gives you complete control over Port B on VIA chip #1. Eight lines for input or output are available, as well as 2 lines for handshaking with an outside device. The I/O lines for Port B are controlled by two locations. One is the port itself, and is located at 37136 ($9110 hex). Naturally you PEEK it to read an input, or POKE it to set an output. Each of the eight I/O lines can be set up as either an input or an output by setting the data direction register properly. It is located at 37138 ($9112 hex).
C PB0
D PB1
E PB2
F PB3
H PB4
J PB5
K PB6
L PB7
M CB2
N GND Ground

Source: VIC-20 User Manual, VIC-20 Programmer's Reference Guide

 

 

 

VIC-20 POWER SUPPLY (PSU) SOCKET

 

Early VIC-20s (pre-Cost-Reduced models) got a 2-pin AC socket on the right side of the unit, further back than the ON/OFF switch. The pinouts for this socket are simple. Both pins expect 9-10V AC voltage from the secondary (output) of the transformer.

Later VIC-20s (the Cost-Reduced, or CR, model) got the same socket as the Commodore 64, so a C64 PSU is 100% ok to use instead if you don't have the VIC-20 PSU that came with it. These are the pinouts of this newer PSU:

Pin Meaning

1 -
2 GND
3 -
4 -
5 +5V DC
6 +9V AC
7 +9V AC

 

Irrelevant for the VIC-20, but as an FYI: some C64 PCB versions have pins 1, 3 and 4 connected also (pins 1 and 3 are to GND, and pin 4 is +5V DC), whilst some have pin 4 disconnected, but a service note says that this should be added via an internal wire.

Of course, depending on the precise model VIC you have (North American model or European, etc), the required input voltage for the transformer differs:

North America = 110-120V AC @ 60Hz, 40W (part # 902503-02)
Europe = 220-240V AC @ 50Hz, 40W (part # ?)