Author: LaTeX (212.234.70.194)
Date: 12-23-2003 15:03
The following was taken out from a SCSI 2 description PDF file. If "OR-tied" means to use an OR gate, I do not see how to link the gate with the bus line cable and all the 8 devices (seven devices + controler). Could it means that you simply have to use a pull up or pull down resistor from the bus line to the +5V or ground in order to allow all devices linked to the same line to "force" the line to a level without damaging the others that will be supposed to be eithier in input mode or hight impedence mode ?
5.6.2 OR-tied signals
The BSY, SEL, and RST signals shall be OR-tied only. In the ordinary operation of the bus, the BSY and RST signals
may be simultaneously driven true by several drivers. No signals other than BSY, RST, and DB(P) are simultaneously
driven by two or more drivers, and any signal other than BSY, SEL, and RST may employ OR-tied or non-OR-tied
drivers. DB(P) shall not be driven false during the ARBITRATION phase but may be driven false in other phases.
There is no operational problem in mixing OR-tied and non-OR-tied drivers on signals other than BSY and RST.
|
