## Computer Science 324 |

**Lecture 02: Computer Arithmetic, Bitwise Operations****Date: Monday, September 10, 2007**

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- 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

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- shiftyproduct

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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.

- Compute the following binary 2's complement problems in 4 bits.
Which answers to you trust?
0001 0001 1001 1111 +0101 +0111 +1111 +0101 ---- ---- ---- ----

- Compute the following binary 1's complement problems in 4 bits.
Which answers do you trust?
0001 0001 0000 1000 +0101 +0111 +1111 +1111 ---- ---- ---- ----

- 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 ---- ---- ---- ---- ---- ----

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