A computer matrix printer has a ribbon carrier (26) pivotally supporting a body (12) of a printing head (14). Solenoid arrangements (32, 34) connect between the body (12) and the carrier (26) and are controlled by electronic means including a microprocessor, whereby the printing head (14) can be moved in opposite directions from a central position, Movement of the printing head (14) is therefore relative to the ribbon (16) held by the carrier (26) and enables printing in any one of three parallel discrete areas on the ribbon (16) holding different coloured inks. The microprocessor can also enable printing in further colours by over-printing one of the discrete colours with another, the over-printing being carried out when the first ink applied to the print-out (18) is still wet. Thus a plurality of colours can be provided with no registration problems and this is particularly suitable for a colour display on a video display unit. Further discrete colours may be included on the ribbon with suitable modification of the arrangement controlling movement of the printing head (14).