Given: Vin = 0.99 V

ADC0801 is an 8-bit analog to digital converter.

It has a resolution of 2^8 = 256 levels.

The input voltage range of the ADC is from 0 to 5 V.

The conversion formula for the ADC0801 is given as:

Digital output = (Vin / Vref) * 256

where Vref is the reference voltage, which is equal to 5 V for the ADC0801.

Calculating the digital output:

Digital output = (0.99 V / 5 V) * 256
= 50.664

The digital output is a binary number, so we need to convert the decimal number 50.664 to binary.

The integer part of the number is 50, which is equal to 0011 0010 in binary.

The fractional part of the number is 0.664. To convert this to binary, we can multiply it by 2 and take the integer part of the result. This gives:

0.664 * 2 = 1.328
integer part = 1

0.328 * 2 = 0.656
integer part = 0

0.656 * 2 = 1.312
integer part = 1

0.312 * 2 = 0.624
integer part = 0

and so on...

Continuing this process for 8 bits, we get:

0.664 * 2 = 1.328 --> 1
0.328 * 2 = 0.656 --> 0
0.656 * 2 = 1.312 --> 1
0.312 * 2 = 0.624 --> 0
0.624 * 2 = 1.248 --> 1
0.248 * 2 = 0.496 --> 0
0.496 * 2 = 0.992 --> 0
0.992 * 2 = 1.984 --> 1

So the final binary value is:

0011 0010.1010

However, the ADC0801 only outputs an 8-bit digital value, so we need to round the binary number to the nearest 8-bit value.

The 9th bit is a 1, so we round up to the next 8-bit value, which is:

0011 0011

Therefore, the digital output of the ADC0801 after INTER goes low is option 'A' - 0011 0011.