Assembly
What is the largest and smallest number that can be represented by a 16-bit SIGNED number?
-2^15 to 2^15 - 1 = -32,768 to 32,767 Smallest: -32,768 Largest: 32,767
What is the largest and smallest number that can be represented by a 8-bit SIGNED number?
-2^7 to (2^7 - 1) = -128 to 127 Smallest: -128 Largest: 127
What is the largest and smallest number that can be represented by a 8-bit UNSIGNED number?
0 to (2^max # bits - 1) = 0 to (2^8 - 1) = 0 to 255 Smallest: 0 Biggest: 255
What is the largest and smallest number that can be represented by a 32 bit UNSIGNED number?
0 to 2^32 - 1 = 0 to 4,294,967,295 Smallest: 0 Largest: 4,294,967,295
What will be printed out from the following code? .data list word 1, 2, 3, 4 .code main proc mov edx, offset list mov eax, [edx] call writeHex exit main endp end main
00 02 00 01
What is a cache hit?
1) Cache Memory: High-speed expensive static RAM both inside and outside the CPU 2) Cache hit: When data to be read is already in cache memory
What are the three basic steps in the instruction execution cycle?
1) Fetch instruction 2) Decode 3) Execute
How many hex digits are there in a byte?
2
Use the following data : word1 WORD 1000h,2000h,3000h,4000h,5000h dword1 DWORD 10000h,20000h,30000h,40000h What is the final value of AX after this code has executed? mov edx,OFFSET word1 + 8 mov ecx,2 mov ax,0 L1: mov ax,[edx] add ax,20h sub edx,4 Loop L1
3020h
Use the following data: dword1 DWORD 10000h,20000h,30000h,40000h Suppose we want EAX to contain the sum of the dword1 array when the following (incomplete) code finishes executing: 1: mov edi,OFFSET dword1 2: mov ecx,LENGTHOF dword1 3: ? 4: ? 5: ? 6: loop L1 Which of the following choices would best fill in lines 3, 4, and 5?
3: mov eax, 0 4: L1: add eax, [edi] 5: add edi, TYPE dword1
Use the following data: arr word 10h,20h,30h,40h Suppose we want al to contain the sum of the array when the following (incomplete) code finishes executing: 1: mov edi,OFFSET arr 2: mov ecx,LENGTHOF arr 3: ? 4: ? 5: ? 6: loop L1
3: sub eax, eax 4: L1: add ax, [edi] 5: add edi, TYPE arr
The hexadecimal value for the binary byte: 1000 1010, if it is unsigned Data.
8A
The central processor unit is connected to the rest of the computer system using what three buses?
Address bus: sends out the address Control bus: send control signals Data bus: sends data
choose the right answer: You declared the following array in your data segment. byte1 BYTE 0BCh,1, 10b when you open the memory window, this is what you will see:
BC 01 02
Name at least four CPU status flags.
CF (Carry Flag) OF (Overflow Flag) SF (Sign Flag) ZF (Zero Flag)
The central processor unit (CPU) contains registers and what other basic elements?
Clock: synchronizes CPY operations Control Unit (CU): coordinates sequence of execution steps ALU: performs arithmetics and bitwise processing Registers: store data during CPU operations
Name all eight 32-bit general-purpose registers
EAX EBX ECX EDX EBP ESP ESI EDI
You are given a before condition of the registers eax, ebx, edx and an instruction. Choose the correct after condition of eax, edx Before condition: EAX: 00 00 00 1B EBX: 00 00 00 0D EDX 00 00 00 00 Instruction: div ebx After condition:
EAX: 00 00 00 02 EDX: 00 00 00 01
You are given a before condition of the registers eax, ebx, edx and an instruction. Choose the correct after condition of eax, edx Before condition: EAX: 00 00 00 03 EBX: 00 00 00 04 EDX: FF 03 FF 01 Instruction: mul bx After condition:
EAX: 00 00 00 0C EDX: FF 03 00 00
You are given a before condition of the registers eax, ecx, edx and an instruction. Choose the correct after condition of eax, edx Before condition: EAX: 01 0F 00 0B ECX: 00 00 00 04 EDX: 0C E0 00 00 Instruction: div cx After condition:
EAX: 01 0F 00 02 EDX: 0C E0 00 03
You are given a before condition of the registers eax, edx and an instruction. Choose the correct after condition of eax, edx: Before condition: EAX: 12 34 56 78 EDX: 9A BC DE F0 Instruction: xchg eax, edx After condition of EAX, EDX:
EAX: 9A BC DE F0 EDX: 12 34 56 78
Which register contains the starting address of data when calling DumpMem?
ESI
Use the following data for the following question in this page: word1 WORD 1000h,2000h,3000h,4000h,5000h dword1 DWORD 10000h,20000h,30000h,40000h What is the final value of AX after this code has executed? mov esi,OFFSET word1 mov ecx,5 mov eax,100h L1: add ax,[esi] add ax,16 add esi,TYPE word1 Loop L1
F150h
you are given a before condition of ecx register and an instruction. Choose the correct after condition of ecx: Before condition of ECX: FF FF FF FF Instruction: inc cl After condition of ecx:
FF FF FF 00
you are given a before condition of ecx register and an instruction. Choose the correct after condition ecx: Before condition of ECX: FF FF FF 3B Instruction: neg cl After condition of ecx:
FF FF FF C5
You are given a before condition of ecx register and an instruction. Choose the correct after condition of ecx: Before condition of ECX: FF FF FF C8 Instruction: add ecx, 6 After condition of ECX:
FF FF FF CE
You are given a before condition of ecx register and an instruction. Choose the correct after condition of ecx: Before condition of ECX: 0A 00 BF 7A Instruction: mov ecx, -1 After condition of ECX:
FF FF FF FF
A quadword is 4 bytes
False
According to masm Assembler the following instruction is valid dec [ebx]
False
Data bus is an internal bus uses binary signals to synchronize actions of all devices attached to the processor.
False
Dead state is the name of the time delay in a CPU caused by differences between the speed of the CPU and RAM
False
Given the following array definition, newArray DWORD 10,20,30,40,50 ArrayCount = (newArray - $)/4 is a valid constant declaration named that automatically calculates the number of elements in the array.
False
Given the following array definition, newArray WORD 10,20,30,40,50 ArrayCount = ( $ - newArray ) / 4 is a valid constant declaration named that automatically calculates the number of elements in this array.
False
Identifiers are by default, case sensitive
False
If the data range for an application is between +200 and -200 decimal, you can use the data type SBYTE to define memory variables to store data.
False
The EIP register can be the destination operand of a MOV, ADD, or SUB instruction.
False
The EQU directive permits a constant to be redefined at any point in a program
False
The PUSH instruction copies a value from the stack to an operand before decrementing the stack pointer.
False
The RET instruction pops the value pointed to by EBP off the stack into the instruction pointer.
False
The binary representation of decimal -42 is 1101 0111
False
The esi register is used as a counter for loops
False
The following instruction will assembly correctly: inc [esi]
False
The following instructions will set the carry flag: mov al, 0FEh sub al,2
False
The following sequence of statements is invalid: .code mov eax, edx .data myByte BYTE 10 .code mov al, myByte
False
The name of the lowest 8 bits of EDX register is DH
False
The signed word with value 9FFH is negative decimal value
False
The signed word with value A7DEh is a positive decimal value
False
The signed word with value FC3h is a negative decimal value
False
When the OF is set, the result of the signed numbers calculation is valid
False
Within the CPU, all calculations and logic operations take place inside the CU
False
one way to translate an unsigned hexadecimal number into binary, repeatedly divide the integer by 2, saving each remainder as a binary digit.
False
What special purpose does the ECX register serve?
Loop counter: used by looping instructions
Why does memory access take more machine cycles than register access?
Multiple cycles required when reading from memory, because it responds much more slowly than the CPU 1) Address placed on address bus 2) Read line (RD) set low (0) 3) CPU waits one cycle for memory to respond 4) Read Line (RD) goes to 1 indicating that the data is on the data bus
Define Multitasking?
Multiple threads of execution within the same program.
What is the function of the OS scheduler?
Scheduler utility assigns a given amount of CPU time to each running program.
A doubleword (on x86 systems) is 32 bits
True
A signed byte can be equal to +127
True
A word (on x86 systems) is 16 bits
True
Assume that List2 begins at offset 2000h. Is 2004h the offset of the third value (5)? List2 WORD 3,4,5,6,7
True
Fetch, decode, execute are the three primary steps of the instruction execution cycle
True
Fetch, decode, execute are the three primary steps of the instruction execution cycle.
True
High-speed memory that reduces the frequency of access by the CPU to conventional memory is called cache memory
True
If AL contains +127 and you add 3 to AL, the Overflow flag will be set
True
If a CPU clock oscillates 10 billion times per second, then the speed of the processor is 10 GHZ
True
If the data range for an application is between +127 and -128 decimal, you can use the data type SBYTE to define memory variables to store data.
True
In 32-bit mode, immediate values pushed on the stack are always 32 bits long.
True
Scheduler of an operating system is responsible for assigning a given amount of CPU time to each running program
True
The 8-bit two's complement of binary 0010.0110 is 1101.1010
True
The 8-bit two's complement of binary 0110 0010 is 1001 1110
True
The 8-bit two's complement of binary is 0000 0010 is 1111 1110
True
The = directive permits a constant to be redefined at any point in a program.
True
The JAE instruction jumps if the (unsigned) first operand is greater than or equal to the (unsigned) second operand.
True
The MOVSX instruction can use a variable as the source operand
True
The PUSHAD instruction pushes all the 32-bit general-purpose registers on the stack.
True
The SDWORD directive is used when defining signed 32-bit integers
True
The USES operator, coupled with the PROC directive, lets you list the names of all registers modified within a procedure.
True
The binary representation of decimal 42 is 0010 1010
True
The following are both valid data definition statements: List1 BYTE 10,20 BYTE 30,40
True
The following instructions will set the Sign flag: mov al, 0FEh sub al,2
True
The four parts of a CPU are: clock, registers, control unit, arithmetic logic unit
True
The hexadecimal representation of decimal 16 is 10h
True
The hexadecimal representation of decimal 17 is 11h
True
The sum of 3AB3h and 0428h is 3EDBh
True
The three types of buses connected to the CPU are: data, address, control
True
The three types of buses connected to the CPU are: data, address, control.
True
There is a one to one correspondence between an assembly instruction and a machine instruction.
True
This data definition statement creates an array of 500 signed doublewords named myListand initializes each array element to the value -1 myList SDWORD 500 DUP (-1)
True
When the CF is set, the result of the unsigned numbers calculation is not valid.
True
When the POP instruction executes, the ESP register is incremented after the value, it points to, is copied from the stack.
True
When you move a 16-bit constant or an 8-bit constant into a 64-bit register, the upper bits of the destination operand are cleared
True
you are given a before condition of ecx register and an instruction. Choose the correct after condition of indicated flags: Before condition of ECX: 00 00 00 20 Instruction: add cl, 3 After condition of flags:
ZF: 0 SF: 0 CF: 0 OF: 0
Which of the following CALL instructions writes the contents of AL to standard output as a character?
call WriteChar
Which of the following CALL instructions writes the contents of EAX to standard output as a signed decimal integer?
call WriteInt
What will be the value of ECX when the following sequence of instructions has executed? push 5 push 10 pop ebx pop eax pop ecx
cannot be determined
Given that edx = 0x0, eax = 0xAAD, ecx = 0x0 What is going to happen as a result of the execution of the following instruction: div cx Why?
dx:ax / cx 0000:0AAD / 0000 = runtime error because you are trying to divide by 0. The cpu is not capable of dividing by 0.
If you have the following array in the data segment arr byte 1,2,3,4 What will be the values of the array after the execution of the following code? push offset arr push type arr push 8 pop eax pop ebx pop esi add [esi + ebx], eax
eax = 8 ebx = 1 esi = &arr [esi + ebx] = 2 = 8 + 2 = 10 arr = 1, 10, 3, 4
Which of the following code sequences assigns the value 10h to EBX?
mov edx,20h push edx mov ecx,10h push ecx pop ebx pop edx
You are given the following array in your data segment arr word 0F8h, 16h, 0DBh, 77h write ONE instruction to toggle the least significant bit of the second and third elements in the array(Toggle means to change a 0 to 1 and a 1 to 0), For example, after your instruction executes, the array should have: 0F8h, 17h, 0DAh, 77h.
xor DWORD ptr [edx + 2], 00010001h
