UTMC APPLICATION NOTE _______________________________________________________________ UT69R000 Bus Control Data Transfer Acknowledge (DTACK )Operation The 69R000 allows the user to insert wait states into read and write cycles performed on the operand bus. As long as Data Transfer Acknowledge (DTACK) is high the bus cycle stretches. The cycle continues to hold until the DTACK goes low and either Bus Error ( BTERR) or Memory Protect (MPROT) become active. MPROT is active high; therefore, the user must ground MPROT or use control circuitry. If a condition occurs that causes MPROT to float, it could cause DTACK to be ignored. OSCIN STATE DTACK MPROT DS Figure 1. DTACK Cycle MPROT High OSCIN STATE DTACK MPROT DS Figure 2. DTACK Cycle MPROT Low 11/98 Page 1 of 1