# Assignment 4 Essays

#1. How many cells can be in a computer's main memory if each cell's address can be represented by two hexadecimal digits? What if four hexadecimal digits are used? Explain your answer.

Answer:

Hexadecimal digits is a base 16 number system and it ranges between 0 and F i.e. 0 - 9 and A - F (10 -15). (Table 1 below shows binary, decimal and hexadecimal representation). Two hexadecimal digits will be between 00 and FF and this will make up to 256 cells i.e. 0 – 255 (16 bits) and for four hexadecimal digits will be between 0000 – FFFF and this makes up to 65536 cells i.e. 0 – 65535 (32 bits).

BINARY NUMBERS | DECIMAL NUMBERS | HEXADECIMAL NUMBERS | 0000 | 0 | 0 | 0001 | 1 | 1 | 0010 | 2 | 2 | 0011 | 3

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Answer:

14,400 bps is equivalent to 1,800 bytes/sec (14400 / 8bits) this will amount to 138.08 days (138 days, 1 hour, 55 minutes and 12 seconds)

Calculations:

20GB = 21,474,836,480.00 bytes (20*1024*1024*1024)

21,474,836,480.00 bytes / 1800 bytes = 11,930,464.71 seconds

11,930,464.71 seconds = 198,841.08 minutes

198,841.08 minutes = 3,314.02 hours

3,314.02 hours = 138.08 days

References:

I. J Glenn Brookshear (2012) Computer.Science.An.Overview.11th.Edition II. Myce (2005) Actual Size of DVD-R 4.7GB? (Online) Available at http://club.myce.com/f33/actual-size-dvd-r-4-7gb-139256/ (Accessed on 3 October 2012) III. wikipedia (2012) Megabyte (Online) Available at http://en.wikipedia.org/wiki/Megabyte (Accessed on 3 October 2012) IV. Dreamincode (2007) Logic Design Assignment (Online) Available at http://www.dreamincode.net/forums/topic/24304-logic-design-assignment/ (Accessed on 3 October