The Multiplexed address and Data lines in the 8085 microprocessor are _____.

Explanation:

The 8085 microprocessor is an 8-bit microprocessor developed by Intel in the mid-1970s. It is notable for its simplicity and ease of use, which made it a popular choice in educational and embedded system applications. One of the key features of the 8085 microprocessor is its multiplexed address and data bus, which helps in reducing the number of pins required for the microprocessor package. The multiplexed address and data lines in the 8085 microprocessor are AD7 - AD0.

Multiplexed Address and Data Lines (AD7 - AD0):

The 8085 microprocessor has 8 multiplexed address and data lines labeled AD7 to AD0. These lines serve a dual purpose: during the first part of the machine cycle, they function as the lower 8 bits of the address bus, and during the second part of the machine cycle, they are used as the data bus. This multiplexing of address and data lines helps in reducing the total number of pins on the microprocessor, thereby simplifying its design and reducing its cost.

Working Principle:

During the first clock cycle (T1), the lines AD7 to AD0 carry the lower 8 bits of the memory address or I/O address. The address is latched into an external latch using the ALE (Address Latch Enable) signal, which is generated by the 8085 microprocessor. Once the address is latched, the same lines (AD7 - AD0) are used to carry the data during the subsequent clock cycles (T2, T3, etc.).

The multiplexing process can be summarized as follows:

1. During T1, the 8-bit address (A7 - A0) is placed on AD7 - AD0.
2. The ALE signal goes high, enabling the external latch to store the address.
3. During T2 and subsequent clock cycles, the lines AD7 - AD0 are used to transfer data between the microprocessor and memory or I/O devices.

Example:

Suppose the microprocessor wants to read data from a memory location with address 2050H. The steps involved would be:

• During T1, the address 50H (lower 8 bits of the address 2050H) is placed on AD7 - AD0.
• ALE signal goes high, and the external latch captures the address 50H.
• During T2, the address 20H (higher 8 bits of the address 2050H) is placed on A15 - A8 lines.
• During T2 and subsequent cycles, the data from memory location 2050H is placed on AD7 - AD0 and read by the microprocessor.