It was founded in 1975 as a DRAM design company, and later branched out into other areas including EDA software, semiconductor reverse engineering, test equipment manufacturing and intellectual property licensing.

By 2011 the business was based exclusively on patent licensing and the company was acquired by Sterling Partners, a US-based private equity firm.

Jamie McDole, General Counsel MOSAID was launched in 1975 by Richard Foss and Robert Harland,[2] who had been employed at Microsystems International.

On their return from the 1975 ISSCC conference where they had presented a paper[3] on MIL's 4kb DRAM, they found that they were no longer employed due to the company's bankruptcy proceedings.

MOSFIT,[9] an efficient MOS transistor modelling program addressing short channel effects was developed and subsequently licensed to Keithley Instruments[10] for use with their parameter analyzer products.

These reports included complete circuit schematics, floorplans, simulations, extracted device parameters and sometimes critique of the techniques employed.

The reports found wide use in competitive analysis, patent licensing negotiations, and outright copying of industry leading devices.

[15] Accelerix,[16] a joint venture with UK-based Symbionics was formed to develop a fully integrated 2D graphics accelerator and frame buffer in a merged DRAM-logic process.

The largest DRAM players would need litigation to encourage them to take a license, beginning with Samsung in 2001[21] followed by Infineon, Hynix, and Micron in later years.

After the fabless component supply business shut down was completed in 2003, MOSAID entered the SIP (Semiconductor IP) market to provide silicon-proven macrocell blocks to system-on-chip developers.

[26] The company retained a small R&D group which developed a high performance NAND flash memory interface called HLNAND,[27] which employed a synchronous point-to-point DDR ring architecture.

In 2013, Sterling Partners and MOSAID established Longitude Licensing in Dublin, Ireland to hold and manage newly acquired patent portfolios.

One such portfolio included thousands of memory related patents acquired from the leading Japanese DRAM manufacturer Elpida.