Sensor RAM as 8-byte First-In-First-Out RAM

Sensor RAM is a type of memory used in electronic devices to store data from sensors. In this question, it is mentioned that the sensor RAM acts as an 8-byte first-in-first-out (FIFO) RAM. Let us understand the different modes in which sensor RAM can be used.

Keyboard Mode

In keyboard mode, the sensor RAM is used to store data from a keyboard. The data is stored in the RAM in the order in which it is typed. However, since the RAM is not a FIFO, the data cannot be retrieved in the order in which it was typed. Therefore, the sensor RAM is not used in keyboard mode.

Strobed Input Mode

In strobed input mode, the sensor RAM is used to store data from a device that sends data in bursts. The device sends a strobe signal to indicate the start of each burst of data. The data is stored in the RAM in the order in which it is received. Since the RAM is a FIFO, the data can be retrieved in the order in which it was received. However, since the data is received in bursts, there may be gaps in the data stored in the RAM. Therefore, the sensor RAM is not used in strobed input mode.

Keyboard and Strobed Input Mode

In keyboard and strobed input mode, the sensor RAM is used to store data from a keyboard or a device that sends data in bursts. The data is stored in the RAM in the order in which it is received. Since the RAM is a FIFO, the data can be retrieved in the order in which it was received. This mode is useful when the same RAM is used to store data from both a keyboard and a device that sends data in bursts.

Scanned Sensor Matrix Mode

In scanned sensor matrix mode, the sensor RAM is used to store data from a matrix of sensors. The sensors are scanned in a specific order, and the data from each sensor is stored in the RAM. Since the RAM is a FIFO, the data can be retrieved in the order in which it was received. This mode is useful when multiple sensors are used, and the data from each sensor needs to be stored and retrieved in a specific order.

Conclusion

In this question, the correct answer is option C, which states that the sensor RAM acts as an 8-byte first-in-first-out RAM in keyboard and strobed input mode. This mode is useful when the same RAM is used to store data from both a keyboard and a device that sends data in bursts.