Computer Systems Organization I - Prof. Grishman

Assignment #1

Answer the following questions from Chapter 2 of Patt and Patel:
#10 and 11 (binary/decimal conversion)
#44 (binary to ASCII conversion)
#45 and 46 (binary/hex conversion)
#37 and 38 (overflow detection)

For #37 and #38, you are to write a Boolean (logical) expression (one involving just AND, OR, and NOT) whose value is a "1" in case of overflow and "0" otherwise, when adding together two 4-bit numbers m and n.  (The book asks for a 4-bit output, with 3 bits being 0, but you can ignore that and just produce the single overflow bit.)  In writing your Boolean expression, you should refer to the bits of the numbers with the subscripts 0 [low-order bit], 1, 2, and 3 [high-order bit], so the numbers being added are  m3 m2 m1 m0 and n3 n2 n1 n0. You may also refer to bits of the sum, s3 s2 s1 s0, and the carries out of the corresponding bits, c3 c2 c1 c0.  In #37 you answer this for two's complement numbers;  in #38 you answer this for unsigned numbers.

Submit your answer in hard copy on a single sheet of paper, in class on Wednesday, September 22nd.  If you are unable to come to class on that day, send the answer in email to