Answer: mainframes

AnswerCrossword Clue
MAINFRAMESLarge, powerful computers
MAINFRAMESIBM inventory
MAINFRAMES"Big iron," in hacker slang
MAINFRAMESData center workhorses
mainframesMAINFRAME, a large computer serving others
mainframesThe central processing unit and primary memory of a computer
mainframesA large high-speed computer, esp. one supporting numerous workstations or peripherals