The number of output pins in 8085 microprocessors are_____.

Question

Examoogle · Accepted Answer

27

Explanation: The Intel 8085 is an 8-bit microprocessor housed in a 40-pin Dual In-Line Package (DIP). Out of these 40 pins, 27 pins are designated as output or bidirectional pins that carry data, address, control signals, or status signals to external devices.

Working Principle: The 40 pins of the 8085 are categorized based on their signal directionality. These include 8 lines for the multiplexed data bus ($AD_0 - AD_7$), 8 lines for the higher-order address bus ($A_8 - A_{15}$), various control lines (such as $\overline{RD}$, $\overline{WR}$, ALE, $S_0, S_1$), interrupt pins (TRAP, RST 7.5, etc.), and power supply pins ($V_{CC}$, $V_{SS}$). When counting pins that perform output functions (including bidirectional pins that output signals), the total count is 27.

Key Formulas: $N_{total} = N_{in} + N_{out} + N_{power} = 40$

Key Points: The 8085 microprocessor uses a 40-pin DIP package.; Data bus pins ($AD_0$ - $AD_7$) are multiplexed, acting as both input and output.; Address bus pins ($A_8$ - $A_{15}$) are unidirectional outputs.; Power pins ($V_{CC}$, $V_{SS}$) and Clock pins are essential for system operation.

Advantages: Standardized 40-pin architecture allowed for easy PCB layout.; Multiplexing of address and data bus reduces the total pin count required.

Disadvantages: Requires external latch (like 74LS373) to demultiplex the $AD_0 - AD_7$ bus.; Limited number of pins restricts parallel I/O capabilities without expansion chips.

Applications: Embedded system design; Educational microprocessor training kits

Additional Info: Option B (40) is the total number of pins on the IC.. The calculation 27 includes address lines, data lines, control signals, and status signals that drive external components.

Answer: A is correct — The 8085 microprocessor consists of 40 physical pins, of which 27 are utilized for outputting or transmitting information (including bidirectional lines) to external peripherals and memory.

Exam Tip: Remember that 40 is the total count, but always differentiate between total pins and functional output/IO pins when analyzing microprocessor datasheets.

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