Computer Architecture Practice Questions

Decide whether each statement is true or false.  You should be able to state a reason as well.

1. The bandwidth of a bus depends on both the clock-speed and the width (in bits).
   True -   400 MHz bus with 32 bits transfers = 4 bytes x 400 MegaHz = 1600 Million bytes per sec
2. A 64-bit CPU must be connected to a 64-bit front-side-bus.  
    False - If a 64 bit CPU is attached ot a 32 bit bus, it can do 2 memory accesses to
      get 64 bits.  
3. A typical amount of RAM for a modern PC is 1024 MB.
    True - that's the same as 1 GigaByte
4. A 3 GigaHertz CPU will always work twice as fast as a 1.5 GigaHertz CPU.
    Almost true, but not quite - It is likely that the 3 GHz processor will be idle much of the time,
      so it won't actually produce twice as much useful work as the 1.5 GHz  
5. The CPU sits in the center of the motherboard, connected to all other components.
     False - the control chips (Northbridge, Southbridge) sit in the "middle" and control communication.
6. A disk-drive can transfer data directly to and from the RAM.
     True - this is called DMA = Direct Memory Access
7. RAM is primary memory.
     True
8. ROM is secondary memory.
     False - it is also primary memory
9. Cache is permanent storage.
     False - it is fast RAM, and will be erased when the power is off
10. Modern graphics cards contain a dedicated CPU.
      True - but this is a Graphics CPU - it does a different kind of work than the main CPU
11. Modern graphics cards contain extra RAM, in addition to the RAM on the motherboard.
      True - This is VRAM (Video Ram) - fsater and more expensive than the DRAM on the motherboard
12. A CPU running at 1 Megahertz would perform 1 MIPS.
      False - it's possible, but probably not
13. The CU is divided into CPU and ALU.
      False -  the CPU is divided into CU (Control Unit) and ALU (Arithmetic-Logic Unit)
14. Data and program instructions are both stored in RAM.
      True - this is called  "von Neumann Architecture"
15. Virtual memory is faster than RAM, because it has no physical limitation.
      False - Virtual memory is slower because it resides on a disk drive
16. A byte might contain 8 bits, 16 bits, 32 bits, or 64 bits, depending on the machine.
      False - a byte contains 8 bits - always.
17. A megabyte is the same as 1024 KiloBytes.
      True
18. A CPU with smaller circuits runs faster because electrons don't need to travel as far.
       False - smaller circuits generate less heat, so it is possible to increase the clock speed
            But smaller circuits by themselves do not increase speed (at least not noticably)
19. A compiler changes high-level-language source code into HTML.
      False - compilers change HLL source code into machine code (numbers)
20. Machine code consists of numbers.
      True - it gets decoded into commands for the CPU
21. The 4 stages in the machine-instruction-cycle are: fetch-execute-encode-store.
      False - it is  Fetch-Decode-Execute-Store
22. Since the machine-instruction-cycle consists of 4 stages, 10 instructions require 40 clock cycles.
      False - modern CPUs use a pipeline architecture and manage about 1 instruction per cycle,
         so 10 instructions will take closer to 10 cycles (perhaps a few more for starting up)
23. Bandwidth only matters in the Internet - it is not important inside your PC.
      False - bandwidth is a bigger problem in the Internet, because it is so incredibly slow,
          but an 800 MHz Front-Side-Bus is considerably faster than an old 100 MHz bus
24. USB sticks use ROM so they can store data even after they are removed from the PC.
       False - they use Flash memory.  ROM cannot be changed, so that wouldn't work.
25. Cache memory is usually considerably smaller than RAM.
      True - cache uses static RAM, which is a lot more expensive than dynamic RAM.
         You might be able to put more cache in the machine, but it's very expensive so nobody does.
26. Virtual memory is usually considerably smaller than RAM.
      False - it is usually set up to be larger than RAM.  The size is flexible, as it uses the hard-disk
27. Cache memory and virtual memory are two different words for the same thing.
      False
28. A server needs more RAM than a PC because it stores more data files.
      False - it needs lots of Hard-Disk storage to store all the files - they are not stored in RAM
         HOWEVER, servers DO generally have more RAM than a PC, for other reasons.
29. If your PC is too slow, you can by the latest CPU and replace your old one.
      Maybe - it depends on how old it is.  If it is several years old, you will probably not be able
         to buy a CPU that fits on the old motherboard, but you could replace the motherboard too.
30. Installing extra RAM will speed up your PC.
      True - if you have relatively little RAM, say 128 MB, your PC will use virtual memory
         and this will slow things down.  By adding more RAM, you can avoid virtual memory.

Calculations - fill in numbers in the blank spaces - some answers are only approximations.

(a)  40 GB =  ___40,000__ MB       (b)  1 MegaBit  =  _125__ KiloBytes       (c) 1 Byte = __8__ bits

(d)  2^ 20  =  10^_6_(approx)         (e)  1 micrometer = _1000_ nanometers     (f) 1,000,000,000 = 2^_30_

(g)  If a typical Mp3 file is 4 MB, how many songs will fit in a 2 GB Mp3 player?   500

(h) The bandwidth of an 800 MegaHertz data bus, with a width of 64 bits, is _6400_ MegaBytes per sec

(i) If a 120 minute video occupies 6 GigaBytes, it must be transferred at _0.8333_ MegaBytes per sec

(j) A 1 MegaBit DSL connection can transfer a maximum of __125__ KiloBytes per second.