公开(公告)号：DE2252182A1

公开(公告)日：1973-05-03

申请号：DE2252182

申请日：1972-10-25

Applicant: IBM

Inventor： PATRICK ROBERT LEWIS ,  RICKARD PATRICK LEE

IPC: H04L69/14 ,  G06F13/00 ,  G06F13/34 ,  G06F3/04

Abstract: A plurality of devices any one of which can request service by a central controlling unit are interconnected in a loop arrangement by an enabling line. The controlling unit is effectively coupled in parallel to all the devices so that the presence of a service request by one of them will immediately initiate operations that will result in one of the devices being granted service. Each device includes logic circuitry to force it to actuate its leg of the enabling line loop if it was the device granted last service or if it does not have a service request present. The connection of the device to the controlling unit results only if it has a service request and receives an enabling line signal from the device preceding it on the loop. Means for bypassing device requests to read high priority requests can be included as can means to initiate data gating overlapping with the establishing of the servicing connection.