1 .Interrupt initiated by the instruction INT 10h to access BIOS functions from the users code can be masked:

a) by execution of the instruction CLI to set interrupt flag bit in the flags register to zero

b) by writing value 20h to the port 20h, i.e. indicating End of Interrupt state for Programmable Interrupt Controller

c) using interrupt service routine (ISR) with zero return code

d) All of the above

e) None of the above

2 . Channel 2 of the Programmable Interval Timer (PIT) Intel 8254 is used to generate sound on computers internal speaker. What unsigned value must be loaded in the counter register of the PIT Channel 2 to generate sound of approximately 100 Hz frequency?

(The oscillator provides roughly 1193182 Hz input to each channel of the PIT. Counter register of PIT channel contains 16-bit non-signed positive value.)

a) 11932

b) 119318200

c) 0064h

d) 100

e) 1800