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Jul1-05, 01:49 PM
JasonJo's Avatar
P: 431
hey I have some computer architecture questions that are freaking me out:

1) what are the disadvantages and advantages of having larger cell sizes for main memory?
i said an advantage would be that we could store larger binary digits but a disadvantage would be that we would have fewer cells to use and you would need a big MAR to store the cell addresses.
any thoughts?

2) for a main memory size of 500,000 bytes, how big should the MAR be? i figured it should be 22 bits, since 500kb almost equal to 8mb, and 8mb is 2^22 bits. am i on the right track with this one?

3) this one i just have no clue on:
Suppose we structure our instruction register such that 6 bits are reserved for the op-code, 20 bits for the first memory address, 20 bits for the second memory address, and 20 for the third memory address. How many distinct op-codes can we use on this machine and what is the maximum size of the memory?

4) this one if you want to try also
-Write a BNF grammar that describes the structure of US telephone numbers, which is in the form (xxx)xxx-xxxx or xxx-xxxx where x is any digit from 0 to 9. (1 point)

-Write another BNF that recognizes the fact that the middle digit of an area code must be a 0, 1, 2, or 3, the first digit of an area code cannot be a 0 or 1, and the first digit of the seven digit phone number cannot be a 0 or 1.

i have no idea what a BNF grammar is! lol

I got the possible op codes down, 2^6 or 64 possible op codes. but the maximum size of memory?? as you can tell, i am having huge difficulties with the structure and function of main memory and MAR/MDR stuff.

any help would be awesome, my final is coming up in a week, im jut trying to get a good grasp on this topic that i am very weak in.
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