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Unit 6: The 8085 Microprocessor Architecture
Notes
Figure 6.5: Special Purpose Registers
6.2.2 Timing and Control Unit
This unit controls and synchronizes all the operations inside and outside of the microprocessor
in the system. The timing and control signals that regulate the transfers and transformations in
the system associated with each instruction are derived from the master clock (CLK). The control
unit also accepts the control signals generated by other devices associated with the microprocessor
system. These control signals generated from outside of the microprocessor also alters the state of
the microprocessor as shown in Figure 6.6.
Most of the microprocessor utilizes an external quartz crystal to determine the clock frequency
(CLK) from which other timing and control signals are developed. The speed of the microprocessor
is related directly to the clock speed, since most of the internal functions are timed by the reference
signal.
Figure 6.6: Detail of Timing and Control Unit
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