CS401 CURRENT FINALTERM PAPER FALL 2013 SHARED BY UJALA ALI FILE 10

Q.no 1: In context of DOS service,writ down the purpose of each instruction given below
mov dx,buffer
mov ah,0x0A
in0x21
Answer:
mov dx,buffer; input buffer
mov ah,0x0A;service A buffered input
in0x21;dos service

Q;NO2:Write the following instruction that saves the current context of AX register into PCB
mov[pcb+b+0],ax
now write instructios for saving the current context of CX,DX,SI,DI,BP,ES register into pcb in same order

Q;no3
How can describe the descriptor catche?

Q.no 4: int 10 of video services while writing graphic pixels,what do the values of register BH,AL,CX and DXcorrespond to?
Answer:
AH=och
BH=page number
AL=pixel colour CX=COLUMN
dx=ROW