Scoot McNairy has been cast in one of the lead roles for AMC drama pilot “Halt and Catch Fire.”The show, set in the 1980s in Texas’ Silicon Prairie, dramatizes a key chapter in the personal computing boom. McNairy (“Argo,” “Killing Them Softly”) will join an ensemble that already includes Lee Pace and Mackenzie Davis. Pace will play a company visionary and Davis a programming prodigy. McNairy will play an engineer who has been left frustrated since the failure of his risky venture. “Halt” was written by Christopher Cantwell and Christopher Rogers, who are exec producing with Melissa Bernstein and Mark Johnson. Juan Jose Campanella is directing the pilot. McNairy is repped by WME and manager John Pierce.