The data comes from the survey made on this page in November.
Some manufacturers use various chips so there are listed more than one in the table.
Besides the RAM speed is listed which was given by the participants. Of course I cannot guarantee that all values are correct, especially the RAM speeds seem to differ very much. BTW who has got a card which is not already listed here can send me the data by mail. Then the table will be updated from time to time. Both VHS and S-VHS output.