8085 Based System Design

Control Signals of 8085

Control Signals of 8085: The 8085 Microprocessor provides RD and WR signals to initiate read or write cycle. Because these Control Signals of 8085 are used both for reading/writing memory and for reading/writing an input device, it is necessary to generate separate read and write signals for memory and I/O devices. The 8085 provides IO/M …

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Power on Reset Circuit of 8085

Power on Reset Circuit in 8051: On reset, the PC sets to 0000H which causes the 8085 to execute the first instruction from address 0000H. For proper reset operation reset signal must be held low for at least 3 clock cycles. The power-on Reset Circuit of 8085 can be used to ensure execution of first …

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Latching Circuit

Latching Circuit: We know that AD0 to AD7 lines are multiplexed and the lower half of address (A0 – A7) is available only during T1 of the machine cycle. This lower half of address is also necessary during T2 and T3 of machine cycle to access specific location in memory or I/O port. This means …

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Input Output Transfer Techniques

Input Output Transfer Techniques: In Input Output Transfer Techniques, the system requires the transfer of data between external circuitry and the microprocessor. In this section, we will discuss different ways of I/O transfer. Program controlled I/O or Polling control . Interrupt program controlled I/O or interrupt driven I/O. Hardware controlled I/O. I/O controlled by Handshake …

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Input Output Interfacing Techniques

Input Output Interfacing Techniques: The most of the microprocessors support isolated I/O system. It partitions memory from I/O, via software, by having instructions that specifically access (address) memory, and others that specifically access I/O. When these instructions are decoded by the microprocessor, an appropriate control signal is generated to activate either memory or I/O operation. …

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Memory Interfacing in 8085

Memory Interfacing in 8085: Memory is an integral part of a microprocessor system, and in this section, we will discuss how to interface a memory device with the microprocessor. The Memory Interfacing in 8085 is used to access memory quite frequently to read instruction codes and data stored in memory. This read/write operations are monitored …

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8085 Clock Circuit

8085 Clock Circuit: The 8085 has on chip clock generator. Fig. 4.1 shows the internal block diagram of the on chip clock generator. The internal clock generator requires tuned circuit like LC, RC or crystal, or external clock source as an input to generate the 8085 Clock Circuit. The internal T-flip flop divides the frequency …

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