S Video has an audio pin

Audio / video socket

Audio / video socket of the C64

At the Audio / video socket of the C64, the audio signal and various image signals are available. The output for the audio signal is individually on a pin of the socket and can be fed separately to the television, monitor or stereo system. The image signal used to control a television or monitor can be picked up either as "composite video" or "S-video". There is also a sound input that is connected to the external sound input of the SID sound chip.


With additional hardware, an RGB or SECAM signal can also be retrofitted to the audio / video socket. Such a mod was especially common in France.

Pin assignment [edit | Edit source]

The audio / video socket is a 5 or 8-pin DIN socket (both DIN 41524). The first C64 models still have a 5-pin socket, just like the one built into the VC 20. A short time later, an 8-pin socket was installed that also provided the chrominance signal.

Outside view of the socket
Pin code signal comment ASSY 326298 (5-pin)VC 20C128
1LUMINANCELuminance, video Y signal, brightnessLUMINANCE6 volts DC, max. 10 mA
for the supply of the HF modulator
like C64
2GNDDimensionsGNDlike C64like C64
3AUDIO OUTSound outputAUDIO OUTlike C64like C64
4VIDEO OUTComposite video signal (mixed color / brightness signal)VIDEO OUT"VLOW" Video Lowlike C64
5AUDIO INSound inputAUDIO IN"VHIGH" video highlike C64
6CHROMINANCEChrominance, video C signal, color--like C64
7-unoccupied--like C64
8-unused or + 5V--5 volts DC

Hints:

The 8-pin socket is not according to DIN 45326 (pin arrangement: 270 °), as is often incorrectly stated and also incorrectly shown, but according to DIN 41524, Pin arrangement: 262 °, horseshoe-shaped. With a little force, the wrong plug can still be plugged into the socket, but when buying a new plug it is better to use the correct one (Reichelt order number: MAS 80S).

At the VC 20 As with the C64 or C128, the composite video signal is on pin 4, and with a higher voltage level again on pin 5. Therefore, a C64 connection cable that only carries the signals on pins 2 (ground), 3 (sound) and 4 (Video) can also be used unchanged for the VC 20 or C128. However, caution is advised when using a special monitor cable, as unsuitable signals can collide here.

PIN 8 is not used for the following ASSY numbers: 250407 [1]

For the following ASSY numbers, PIN 8 is assigned + 5V: 250425 [2], 250466 [3], 250469[4]

When installing a second SID module (Stereo SID) Pin 5 is often suggested for the second (right) channel, i.e. the audio input (cf. 64 edition 11/86). Although this is compatible with the pin assignment on stereo systems that previously also had a 5-pin DIN socket installed, it is not recommended due to the common use of cinch plugs today. The free pin 7 is ideal here.

Signal description [edit | Edit source]

VIDEO OUT: Video output

This is a television signal in the format of the analog television signal before it is modulated onto an RF carrier (television frequency). With the C64 it corresponds to the standard format for PAL (Europe) or NTSC (USA). In practice it is the same signal that is present at the antenna socket, but it is not modulated. When using a television with a corresponding connection, it is preferable to the antenna connection, because the loss of quality due to the modulation in the C64 and the demodulation in the television set do not apply.

Since the signal contains the information about the image brightness and the color, one speaks of a composite video signal (mixed signal), which is also FBAS (F.work-B.ild-A.ustast-S.synchronous signal) or CVBS (C.olour V.ideo B.lanking S.ignal) is called.

LUMINANCE: Luminance, Y

This (television) signal contains all the information required for black-and-white image transmission. It consists of the image signal, the blanking signal and the synchronization signal and therefore becomes B.ild-A.ustast-S.Synchronic signal or BAS signal for short.

CROMINANCE: Chrominance, C.

The chrominance (color) is a part of the S-video signal (also Y / C signal), the other part is the luminance signal (brightness). These two signals form an analog video format that is of better quality than the composite video signal (VIDEO OUT) due to the separation on two signal lines. S-Video is used with many monitors and should also be preferred if you are using a television and this is equipped with a corresponding input (separately or on the SCART connection).

AUDIO OUT: Audio output

max. 2 V audio audio signal from the SID, decoupled by transistor

AUDIO IN: Audio input, (max. 3 V)

This audio input is connected to the external audio input (pin 26) of the SID sound chip. Depending on the programming, the SID sends this signal either via the built-in filter or directly to the output stage of the SID. Together with the internally generated voices, it is then output again via the volume control built into the SID.

Pin assignments S-Video and SCART [edit | Edit source]

The following are the pin assignments for the S-Video and SCART sockets. This information should suffice to find or build a suitable cable for any device configuration.

signalC64-A / VSCART socketS-video
Dimensions24, 171,2
Audio32, 6-
Video420/-*-
Luminance (Y)1-/20*3
Chroma (C)6-/15*4
* Only with Y / C video via SCART. Not all devices with a SCART connection can use Y / C signals!
  1. ↑ Circuit 251138
  2. ↑ Circuit 251469
  3. ↑ Circuit 252278
  4. ↑ Circuit 252312 and 250469 (Rev. B)