80C186EB/80C188EB Microprocessor User's Manual - CEUNES

BUS INTERFACE UNITT OE , T ACC and T CE define the maximum data access requirements for the memory device. Thesedevice parameters must be less than the value calculated in the equation column. An equal to orgreater than result indicates that wait states must be inserted into the bus cycle.T DF determines the maximum time the memory device can float its outputs before the next buscycle begins. A T DF value greater than the equation result indicates a buffer fight. A buffer fightmeans two (or more) devices are driving the bus at the same time. This can lead to short circuitconditions, resulting in large current spikes and possible device damage.T RHAX cannot be lengthened (other than by slowing the clock rate). To resolve a buffer fight condition,choose a faster device or buffer the AD bus (see “Buffering the Data Bus” on page 3-35).CLKOUTT1 T2 T3 T4S2:0Status ValidBHEALEA19:16A15:8RFSHA15:0[AD7:0]Address ValidAddressValidA18:16 = 0, A19=Valid StatusValidDataValidRDDT / RDENA1084-0AFigure 3-19. Typical Read Bus Cycle3-21