Serial NOR is a very common technology, as its SPI-interface is widely used in communication equipment.
There are several different SPI NOR Flash options available: single, double, quad, and even octal SPI NOR Flash. The multiples of SPI refer to the number of SPI channels that a device offers.
Quad SPIs are suitable for direct code execution, provided the CPU attached offers this option.
We offer SPI NOR Flash from the following memory manufacturers:
MEMPHIS Electronic GmbH
Basler Str. 5
61352 Bad Homburg
Germany
Phone: +49 6172 90350
Email: info@memphis.de
512Kb – 2Gb 
up to 200MHz
commercial, industrial and automotive grades
SPI / Dual / Quad
1.2V - 3V
SOP16, TFBGA24, WSON8