V22.0201-001: Comp. Sys. Org. I (Honors)

Mid-term Study Guide

Exam Rules

1. The mid-term exam will be on Tuesday, October 15, 2002.

2. It will be worth 14 points (out of a total of 100 for the course).

3. It will cover the material in chapters 1 8 of the Dewar notes.

4. It will consist of one question in which you have to write an x86 procedure (roughly 20 lines), and a series of short-answer questions about x86 instructions.

Although anything from chapters 1 8 is fair game, the emphasis will be on two's complement arithmetic, arrays, bit manipulation (shifting and logical operations), and procedures. You should study that material thoroughly. In particular, it is a good idea to review the extended examples which appear at the end of most chapters.  There may also be a question which asks you to convert one or two machine language instructions to binary -- in particular, a jump instruction.

You will be allowed the entire period.  It will be an open-book, open-notes exam.

Programs are graded primarily on correctness. There will be no penalty for small differences in efficiency, although we may penalize for grossly inefficient programs or programs with totally useless instructions. Comments on the programs are encouraged, both to make grading easier, and to allow for assignment of partial credit.

Study Suggestions

a.  Working on assignment 2 (at least the non-extra-credit version) is good preparation for the mid-term, since the assignment involves both bit manipulation and arrays.

b.  You are now "responsible" for four flags:  Z, C, S, and O.  To check your understanding of these flags, try a simple program such as  MOV  AL,50H / ADD   AL,50H / HLT   with the Dewar Debugger.  See if you can correctly predict what the flag values will be after the program halts.  Try this for a few constants.

c.  Exercise 6.1. is a good check that you understand what the logical and shift instructions do.  Again, if you're not sure of the answers, type the code in and run it with DDB.

d.  Be sure you understand how to use masking and/or shifting to extract some of the bits from a byte -- for example, how to get the three high-order (or the three low-order) bits of a byte.

e.  Be sure you can 'assemble' a jump instruction to binary;  if in doubt, check your results using DAS.