Computer Science 324 Computer Architecture Mount Holyoke College Fall 2007

Agenda

• Announcements
  • Join us for a "welcome back" pizza lunch on Thursday in Clapp 222
• Lecture assignment recap
• Character representations
• Memory model and pointers
• Computer arithmetic
• Bit manipulations
  • logical operations and shifts
• Lab 1 Out
  • Unix/Linux tutorial now available

Examples

• shiftyproduct

Lecture Assignment

Due at the start of class, Wednesday, September 12.

Turn in short answers to these questions. Please turn in a hard copy (typeset or handwritten are OK). We will discuss these questions during class, so no late submissions are accepted.

The readings for next time are P&H Sections 2.1-2.3, and the first part of my notes on the MIPS ISA.

1. Compute the following binary 2's complement problems in 4 bits. Which answers to you trust?

    0001      0001      1001      1111
   +0101     +0111     +1111     +0101
    ----      ----      ----      ----
   
   
   

2. Compute the following binary 1's complement problems in 4 bits. Which answers do you trust?

     0001      0001      0000      1000
    +0101     +0111     +1111     +1111
     ----      ----      ----      ----
   
   
   

3. The following problems are expressed in 8 bit, hexadecimal, 2's complement. Compute the result as 16 bit 2's complement expressed in hex. Which answers do you trust?

     FF        FF        01        4c       7f       80
   + 11      + FF      + 7F      x 04     x 7f     x 80
   ----      ----      ----      ----     ----     ----
   
   

4. (Moved to next lecture assignment)
5. True or false: The signed product of two signed n-bit numbers can always be correctly expressed as a signed 2n-bit number. Justify your answer.