Question

Frequency range of 8257 is

• A. \( \text{500Hz to 3MHz} \)
• B. \( \text{250Hz to 3MHz} \)
• C. \( \text{500Hz to 2MHz} \)
• D. \( \text{250Hz to 2MHz} \)

Hint:

For specific integrated circuits (ICs) like the 8257 DMA controller, 8255 PPI, 8259 PIC, etc., it's often helpful to remember their key specifications, including their operating frequency ranges. These chips are fundamental components in early microprocessor systems, and their characteristics are part of the core knowledge in digital electronics and microprocessor architecture.

Answer 1

The Correct Option is B

The Intel 8257 is a Programmable DMA (Direct Memory Access) Controller. It was a popular peripheral chip used in conjunction with microprocessors like the 8085 and 8086 to offload data transfer operations from the CPU. The operating frequency range of such historical peripheral chips is crucial for their compatibility with different system clock speeds. For the Intel 8257 DMA controller, its specified frequency range is typically from 250 Hz (minimum operating frequency) to 3 MHz (maximum operating frequency). This range allows it to be used in various systems with different clock speeds. Let's evaluate the options: (A) \( \text{500Hz to 3MHz} \): The upper limit (3MHz) is correct, but the lower limit (500Hz) is not the standard minimum. (B) \( \text{250Hz to 3MHz} \): This range matches the typical specifications for the Intel 8257 DMA controller. (C) \( \text{500Hz to 2MHz} \): Both the lower and upper limits are incorrect compared to standard specifications. (D) \( \text{250Hz to 2MHz} \): The lower limit (250Hz) is correct, but the upper limit (2MHz) is incorrect. Therefore, based on the standard specifications of the Intel 8257 DMA controller, its frequency range is 250Hz to 3MHz.