Control Data reported a first-quarter loss of $21.2 million, more than double the $9.2-million loss that it reported a year earlier. First-quarter computer business revenue totaled $796.1 million, compared to $890.5 million in the first quarter of 1985. The net loss of the computer business was $42.6 million, compared to $11.5 million in the first quarter of last year. Control Data’s Commercial Credit division had first-quarter net earnings of $21.4 million, compared to $2.3 million in the first quarter of 1985. The division’s results are not included in overall revenue figures.