@Rob, Only if you use 16 bit organisation. I use 8 bit (ORG pin 6 to ground), so I need 10 clocks. Thanks for the link anyway.

But don't worry about it anymore I solved the problem. Don't say 93C46 to all the 93C46 around. Microchip is the only manufacturer who don't use a prefix (fairchild use FM, ST use M, ...). Since there was no prefix on the chip I use, I thought it was a microchip with selectable memory organisation. After reading several datsheets I modify my code assuming it was a Fairchild fixed 16 bit chip and everything works fine.