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Jul1-05, 03:43 PM
Sci Advisor
HW Helper
P: 1,593
Interesting questions Jason. People here can help you and you might find additional help down below in the Software and Hardware forums. Try those too.

Quote Quote by JasonJo
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?
Let me try:

Do you mean number of bits per memory address? Those bits are transmitted from RAM to CPU via a data bus consisting of individual electric lines on the circuit board. Switching from 8 to 16 makes designing the boards more complicated.

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?
I assume you mean memory address register? Or instruction register as I see it. RAM is accessed in bytes: one address for each byte. How many bits does it take to write 500,000 in base 2?

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?
Same dif: What's the largest number you can write with 6 bits? 20 bits?

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.
BNF? you got me dude . . .