1. A memory control method of controlling an access to a memory for a writing and a readout, the memory control method comprising: carrying out a plurality of techniques for code conversion on original data; selecting one of the plurality of techniques for said code conversion to produce converted data, based on an amount of 1s in said converted data; writing said converted data into said memory; and outputting reproduced data which is provided by carrying out an inverse transformation of said code conversion on said converted data which is read out from said memory, to a host system for processing said original data.