Boeing [BA] last Friday said it has acquired a business unit from CPU Technology Inc. that makes microprocessors that provide cyber security protection to onboard mission critical systems.

Terms of the deal were not disclosed.

CPU’s Acalis unit makes microprocessors that contain unique hardware and software to guard mission-critical onboard systems. Before the acquisition, Boeing purchased Acalis’ microprocessors for use in its manned and unmanned aircraft systems.

“Acalis provides security-on-a-chip that can help defend the manned and unmanned aircraft we build at Boeing today and in the future for customers around the world,” Chris Chadwick, president of Boeing Military Aircraft, said in a statement. “With these processors onboard, warfighters can complete their missions and not be sidelined by malware, cloning and other cyber threats against the aircraft’s systems.”

Acalis, which has about 40 employees and is based in California, will become part of Boeing Military Aircraft’s Global Strike division.

Boeing said that Acalis has some non-Boeing contractual work which will continue until the contracts are fulfilled.

CPU did not use a financial adviser on the deal. With the sale, CPU has ceased operations.