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saltydog
saltydog is offline
#2
Jul1-05, 03:43 PM
Sci Advisor
HW Helper
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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 . . .