8087 has 5 MHz as its clock frequency because the coprocessor must have the same clock frequency as that of the main processor.
12. How are negative numbers stored in a coprocessor?
A. 1’s complement
B. 2’s complement
C. decimal
D. gray
Answer: B
In a coprocessor, negative numbers are stored in 2’s complement with its leftmost sign bit of 1 whereas positive numbers are stored in the form of true value with its leftmost sign bit of 0.
13. How many bits are used for storing signed integers?
A. 2
B. 4
C. 8
D. 16
Answer: D
Signed integers in a coprocessor are stored as a 16-bit word, 32-bit doubleword, or 64-bit quadword.
14. Which of the processor has an internal coprocessor?
A. 8087
B. 80287
C. 80387
D. 80486DX
Answer: D
8087 is an external IC designed to operate with the 8088/8086 processor but 80486DX is an on-chip coprocessor that is, it does not require an extra integrated chip for floating-point arithmetic.
15. What are the two major sections in a coprocessor?
A. control unit and numeric control unit
B. integer unit and control unit
C. floating-point unit and coprocessor unit
D. coprocessor unit and numeric control unit
Answer: A
The Control unit interfaces the coprocessor with its main microprocessor whereas the numeric control unit can execute the coprocessor instructions.
16. What are the three stages included in pipelining of 80386?
A. Fetch, decode, execute
B. Fetch, execute, decode
C. Execute, fetch, decode
D. Decode, execute, fetch
Answer: a
The instruction can execute in a single cycle which is done by pipelining the instruction flow. The address calculations are performed as the instruction proceeds down the line. Pipelining may take several cycles, an instruction can potentially be started and completed on every clock edge, thus achieving the single-cycle performance.
17. How instructions and data are accessed to pipeline stages of the 80486 processor?
A. Through an internal unified cache
B. Through external unified cache
C. Through external cache
D. Through multiple caches
Answer: a
In order to have instructions and data in the pipeline, the 80486 has an internal unified cache to contain both data and instructions. This helps in the independency of the processor on external memory.
18. Which of the following processor possesses a similar instruction of 80486?
A. 8086
B. 80286
C. 80386
D. 8080
Answer: c
The instruction set is the same as that of 80386 but there are some additional instructions available when the processor is in protected mode.
19. What are the two external interrupt signals in 80386?
A. IV and NMI
B. NMI and INTR
C. INTR and IV
D. PC and NMI
Answer: b
The 80386 has two external interrupt signals which allow external devices to interrupt the processor. The INTR input creates a maskable interrupt while the NMI creates a non-maskable interrupt.
20. How many bit vector number is used in an interrupt cycle of 80386?
A. 4
B. 8
C. 16
D. 32
Answer: b
While an interrupt cycle is running, the processor possesses two interrupts to acknowledge bus cycles and reads an 8-bit vector number. This vector is then used to locate, within the vector table and it has the address of the corresponding interrupt service routine. NMI is automatically assigned as vector number 2.
