Direct Physical Selection
Original Publication Date: 1985-Mar-01
Included in the Prior Art Database: 2005-Feb-18
This article describes a direct physical selection technique which has separate card and board select inputs, thereby providing a common card selection method. Fig 1a represents a model of a serially repowered I/O bus. The bus units shown are the bus control unit (BCU), input/output processors (IOP) and repower (RP). Fig. 1b represents the board and card socket wiring for the associated bus units and the driver/receiver (d/r) requirements for the type of bus unit occupying these card socket positions. Fig. 1b shows common I/O pin connections at each card socket for address data (A/D) bus bits 00-31 that are repowered (dashed lines) through the repower bus unit. The remainder of the I/O bus lines are not shown. A new line, board select (B/S), is also a common I/O pin connection for each card socket but is not repowered.