Question

What will be the foldback memory address range of the following memory chip while interfacing with 8085 microprocessor?

• A. 2000H-20FFH
• B. 2100H-27FFH
• C. 2000H-27FFH
• D. 2400H-24FFH

Hint:

In interfacing memory with a microprocessor, the size of the memory and the addressing scheme determine the address range used by the chip.

Answer 1

The Correct Option is C

 

Step 1: Understand the memory chip and addressing. 
The memory chip in question is the 8155 static RAM, with a size of 256 x 8, which provides a total of 2048 bytes (2K). 

- The 8085 microprocessor uses a 16-bit address bus, allowing it to access 64KB of memory. 

- The 8205 decoder takes the higher 3 bits (A13, A14, A15) and generates the appropriate chip enable (CE) signals based on the address range specified by the memory chip.

Step 2: Determine the foldback memory range. 
Given that the 8155 memory chip is 2K (2048 bytes), it occupies the range starting from the base address \( 2000H \). The range of 2K memory in hexadecimal is \( 2000H \) to \( 27FFH \).

Step 3: Conclusion. 
Thus, the foldback memory address range for the memory chip is \( 2000H - 27FFH \), which corresponds to option (3).