bad criminal record - working visa to USA

a friend was convicted more than 20 years ago in a diplok crown court on a terrorist charge ( armed robbery) he was sentenced to 2 years.

he wants working visa to USA and has a work pack etc made up from an employer.

will he get a visa or not ? also crimes of serious assults etc on his record but no drugs.

A visa for the USA with a terrorist charge? No chance...although you've said armed robbery/terrorist charge...both? The Rehabilitation of Offenders Act does not apply to United States visa law so it's irrelevant how many years have passed since they were sentenced for the crime/crimes.
The visa application will be blocked by the United States Department of Homeland Security Customs and Border Protection (DHSCBP).