U.S. patent application Ser. No. 138,806 entitled "Electrically Erasable Programmable Read-Only Memory" filed by Frank M. Wanlass on Apr. 9, 1980 and assigned to the assignee of this application describes the first electrically erasable programmable read-only memory (EEPROM) formed as a complementary metal oxide semiconductor (CMOS) device including an n-channel floating gate tunneling metal oxide semiconductor field effect transistor (FATMOS FET) formed in a p-type well in which the electron tunneling region does not overlie the drain diffusion but instead overlies the source to drain channel. In the above-referenced application, Wanlass teaches that each FATMOS FET requires its own individual source and drain diffusions which may be shared among a plurality of FATMOS FET's in a single horizontal row. However, in accordance with the teachings of Wanlass, each row of FATMOS FET's includes its own source and drain diffusions, there being no sharing of diffusions between rows. In fact, because the Wanlass device includes a resistor connected between the drain diffusion and its bias voltage source, it is not possible to share the drain diffusion between adjacent transistors of the type disclosed by Wanlass when it is desired to simultaneously write different logic states into two adjacent memory cells in the same vertical column. Accordingly, it does not seem possible to share a diffusion between adjacent transistors of the type disclosed by Wanlass which are in the same column, limiting the device density.