Introduction to Computing Systems-Errata

Mail all unlisted errata and corrections to: starolis@ece.utexas.edu

Note: The number(s) in parentheses next to each item refers to the edition and printing which contains the error. That is, 1.1 indicates an error in the first edition's first printing that has been corrected in subsequent printings, whereas (1.2) indicates the error is in both the first and second printings of the first edition. (2) indicates an error found in the second edition, which is currently only available in the first printing.

Errata

Page xii, Appendix D Title. (1.1) Should read: The C Programming Language

Page 22, Section 2.3. (1.1,1.2) Line 22:

Replace: add A to the complement of A

With: add 1 to the complement of A

Page 33, Figure 2.2. (1.1,1.2)

Replace: N = -1^S...

With: N = (-1)^S...

Page 34, Example 2.8. (1.1) The exponent field should be 10000001, not 10000011

Page 38, Problem 2.5. (1.1) Using 5 bits to represent each number, write...

Page 39, Problem 2.13. (1.1) binary representations, not binary numbers

Page 39, Problem 2.14. (1.1,1.2) Replace the current problem with the following:

    Note that in the ADD step performed below, the addition is independent
    of what the two representations being added mean.

    1. Represent the values 7 and -6 as 1's complement integers. ADD the two
    binary representations. What is the binary result. What decimal value does
    that 1's complement result represent.

    2. Represent the values 7 and -6 as signed magnitude integers. ADD the two
    binary representations. What is the binary result. What decimal value does
    that signed magnitude result represent.

    3. Represent the values 7 and -6 as 2's complement integers. ADD the two
    binary representations. What is the binary result. What decimal value does
    that 2's complement result represent.

Page 40, Problem 2.18. (1.1) Replace the problem with the following:

Express the negative value -27 as a 2's complement integer, using 8 bits. Repeat, using 16 bits. Repeat, using 32 bits. What does this illustrate with respect to the properties of sign extension, as they pertain to 2's complement representation?

Page 41, Problem 2.32. (1.1) In Example 2.5, what are the masks used for?

Page 43, Problem 2.41 (1.1) ASCII code for three is 0011 0011, instead of 0110 0011, as shown.

Page 44, Problem 2.14 (2)

Replace: Add the following binary representaions.

With: Add the following bit patterns.

Page 44, Problem 2.49 (1.1,1.2) Append the following to the problem statement:

[Hint: In the first four cases, express each value as a decimal number. In the fifth case, express the value as a sequence of characters that one could type on a keyboard, for example.]

Page 63, Section 3.3.4 (2) First sentence of first paragraph should read:

Figure 3.17 illustrates…

Page 64, Section 3.5. (1.1,1.2) First sentence should read:

We now have all the tools we need to describe one of the most important structures in the electronic digital computer, its memory.

Page 85, Problem 3.8. (2)
Replace Y = A AND (B OR C)
with Y = NOT ( A AND ( B OR C))

Page 87, Problem 4.5. (1.1,1.2) Part 2c, Change to:

Interpret locations 6 and 7 as an IEEE Floating Point number. Location 6 contains number[15:0]. Location 7 contains number[31:16].

Page 87, Problem 4.5. (1.1) Part 2d, Change to: Interpret location 0 and 1 as unsigned integers.

Page 88, Problem 4.10. (1.1) NOT instead of NOP

Page 99, Problem 5.3.4. (1.1,1.2) R2 is encoded wrong in the instruction. It should read 0110 001 010 011101.

Page 100, Figure 5.2. (1.1) The field breaks are done wrong for the instruction at address x30FC, they should read:

1010 011 011110100

Page 102, Section 5.4.2. (1.1,1.2)

Lines -7 and -9: Replace R4 with R3

Page 105, Figure 5.5. (1.1) Sentinel is misspelled in the decision box

Page 105, Section 5.4.4. (1.1,1.2) Line -1:

Replace: x3101

With: the instruction at x3001

Page 108, Figure 5.7. (1.1,1.2) The formula in the Prepare Output box should read (R0 <- R2 + x30)

Page 114, Problem 5.1. (1.1) First line: NOT instead of NOP

Page 114, Problem 5.2. (1.1) Rephrase as: What is the page number for each of the following LC-2 memory addresses? Express your answers in hex.

Page 115, Problem 5.5. (1.1) Change parts 2, 3, and 4 as follows:

2. Write an LC-2 instruction that determines whether both machines 2 and 3 are busy.

3. Write an LC-2 instruction that indicates none of the machines are busy.

4. Change machine 13 to 6.

Page 116, Problem 5.10. (1.1,1.2) The last line of the program: The address should be 0100 0101 0110 1000, not 0100 0101 0110 0111.

Page 117, Problem 5.18. (1.1) Part 5, second line: Replace "did not change any of the opcodes" with "kept the number of opcodes at 16".

Page 117, Problem 5.19. (1.1) First line:

The LC-2 ISA contains the instruction LDR DR, BaseR, offset. After the LDR instruction is decoded, the following operations (called microinstructions) are carried out to complete the processing of the LDR instruction:

*Insert here lines 3 through 8 of the problem statement*

*Replace the subsequent items 1 and 2 with the following*

1. The MOVE instruction is not really necessary since it can be accomplished with a sequence of existing LC-2 instructions. What sequence of existing LC-2 instructions implements (also called "emulates") MOVE R0,R1 ?

2. If the MOVE instruction were added to the LC-2 ISA, what sequence of microinstructions, following the decode operation, would emulate MOVE DR,SR ?

Page 117, Problem 5.20. (1.1) Restate the problem as follows:

As stated in the text, we have saved the JMP/JSR and JMPR/JSRR for Chapter 9. Those who can't wait can find the description of these two instructions in Appendix A. Note that JMP and JSR have exactly the same opcode, but their execution depends on the value of L. Why is the case L=0 irrelevant to the LC-2 ISA? The opcodes JMPR and JSRR also have exactly the same opcode. However, for JMPR/JSRR, the case L=0 is not irrelevant. Why?

Page 118, Problem 5.21. (1.1) First line: Change Section 3.5.5 to Section 5.3.5.

Page 129, Section 6.2.2. (1.1,1.2) First sentence: the load instruction should be 0010

Page 131, Section 6.2.2. (1.1,1.2) Line -4: Replace "the opcode 0100" with "the opcode 0010"

Page 136, Problem 6.7. (1.1,1.2) The first line of machine code should be removed and all of the addresses should be shifted down by one, so that x3001 becomes x3000 and so on.

Page 148, Problem 5.22. (2)
Replace : x3010 1110 1110 0011 0001
With : x3010 1110 1100 0011 1111

Page 155, Problem 7.14. (1.1) We got the 0 and the 1 wrong! So, change the wording in lines 5 and 6 so it reads:

If the strings are the same, the program terminates with the value 1 in R5. If the strings are different, the program terminates with the value 0 in R5.

Page 161, Section 8.2.2. (1.1,1.2) Line 4 of code in middle of the page: The branch instruction should be unconditional, so replace with BRnzp.

Page 163, Section 8.3.2/3. (1.1,1.2) Both pieces of code on the page: The branch to NEXT_TASK should be unconditional, so replace with BRnzp.

Page 164, Section 8.4. (1.1,1.2) Line 1: Replace "character!" with "character?"

Page 165, Figure 8.3. (1.1,1.2) Lines 11 and 20: Branches should be unconditional, so replace with BRnzp at both locations.

Page 173, Section 9.1.2. (1.1,1.2) Element 2, Append the following line:

Cross-reference Table A.3 on pg. 449

Page 173, Figure 9.2. (1.1) The figure should contain:

Page 176, Section 9.1.5. (1.1,1.2) Line -10: Application is misspelled

Page 181, Figure 9.6. (1.1,1.2) Lines x0F and x12 comments: replace '$' with 'x'

Page 181, Figure 9.6. (1.1,1.2) Line 36 (or x24 in the program):

Replace: Message .FILL "Halting the machine."

With: Message .STRINGZ "Halting the machine."

page 187, line -9. (2)

Should read: greater than LC+1+255 or less than LC+1-256,

Page 192, Problem 9.4. (1.1,1.2)

Replace: BRNZP L2

With: BRnzp L2

Page 193, Problem 9.5. (1.1,1.2)

Replace: DATA .BLKW 10 x0000

With: DATA .BLKW 10

Replace: BR G_TEXT

With: BRnzp G_TEXT

Page 194, Problem 9.6. (1.1,1.2) Code at top of page, a period has taken the place of a comma, so:

Replace: LD R4.OADDR

With: LD R4,OADDR

Page 194, Problem 9.9. (1.1,1.2) Problem 5.20 is more appropriate for this chapter and will be inserted as the last problem of the Chapter 9 problem set.

Page 196, Problem 7.20. (2)
    Correct Part (a) to read:
    .ORIG x5000
    AND R0, R0, #0
    ADD R0, R0, #15
    ADD R0, R0, #6
    STI R0, PTR
    HALT
    PTR .FILL x4000
    .END

Page 196, Problem 7.21. (2)
    Correct the program to read:
    .ORIG     x3000
    AND     R0, R0, #0
    ADD     R2, R0, #10
    LD     R1, MASK
    LD     R3, PTR1
    LOOP LDR     R4, R3, #0
    AND     R4, R4, R1
    BRz     NEXT
    ADD     R0, R0, #1
    NEXT ADD     R3, R3, #1
    ADD     R2, R2, #-1
    BRp     LOOP
    STI     R0, PTR2
    HALT
    MASK .FILL x8000
    PTR1 .FILL x4000
    PTR2 .FILL x5000

    What does the program do?

Page 212, Figure 10.16. (1.1,1.2) Reverse all decisions on the flowchart (i.e. replace yes with no and vice versa)

Page 213, Figure 10.17. (1.1,1.2)

Replace: ASCIIBUFF .BLKW 4, x0000

With: ASCIIBUFF .BLKW 4

Page 217, Figure 10.19. (1.1,1.2) The box that says Clear Stack should reference Figure 10.25, rather than 10.23

Page 218, Figure 10.20. (1.1,1.2) The line BRz OpClear should reference Figure 10.25, rather than 10.23

Page 220, Figure 10.23. (1.1,1.2)

Replace: StackBase .BLKW 9, x0000

With: StackBase .BLKW 9

Page 222, Problem 10.8. (1.1) Part 3, Replace ZYXWVUTSR with ZYXW.

Page 222, Problem 10.9. (1.1) Change the problem statement to:

Describe, in your own words, how the Multiply step of the OpMult algorithm in Figure 10.12 works. How many instructions are executed to perform the Multiply step? Express your answer in terms of n, the value of the multiplier. [Note: If an instruction executes 5 times, it contributes 5 to the total count.] Write a program fragment that performs the Multiply step in fewer instructions if the value of the multiplier is less than 25. How many instructions are executed now, in terms of n?

Page 235, Section 11.5.3. (1.1,1.2) Replace the last sentence of the section, lines 6-8 with:

Since #define and #include are preprocessor directives and not C statements, they are not terminated by semicolons.

Page 235, Section 11.5.4. (1.1,1.2) Line -8:

Replace: printf("43 plus 59 as a character is %d.", 43 + 59);

With: printf("43 plus 59 in decimal is %d.", 43 + 59);

Page 239, Problem 11.9. (1.1) This problem should read:

What happens if we change the second-to-last line of the program in Figure 11.2 from:

printf("%d\n", counter);

to:

1. printf("%c\n", counter + 'A');

2. printf("%d\n%d\n", counter, startPoint + counter);

Page 244, Section 12.2.1. (1.1,1.2) First paragraph under "int"; third sentence:

The range of values for an int in the LC-2 is incorrectly listed as -32,768 to -32,767. The correct values are -32,768 to +32,767.

Page 249, Section 12.2.4. (1.1,1.2) Line -2:

Replace: int sevenBits = 0xA1234;
With: int sevenBits = 0x1234;

Page 249, Problem 9.19 (2)

The devices should have been labeled (1)-(4) instead of (a)-(d).

Page 250, Section 12.2.5. (1.1,1.2) Second paragraph of section:

Replace: The variable i is an integer variable and is stored at offset 3. The variable start is also...

With: The variable counter is an integer variable and is stored at offset 3. The variable startPoint is also...

Page 255, Figure 12.7. (1.1,1.2) 7th line of code:

Replace: STR R4, R6, #4 ; y = 3;

With: STR R4, R6, #4 ; y = 5;

Page 259, Section 12.3.4. (1.1,1.2) Second formula on page:

Replace: x = a * b + c * d / 2;

With: x = a * b + c * d / 4;

Page 285, Problem 10.11. (2)

Replace : contents of locations x00F1 and x00F2
With : contents of locations x01F1 and x01F2

Page 285, Problem 10.14. (2)

Replace : If the buffer is full (i.e, if a character has been stored in location x40FF)
With : If the buffer is full (i.e, if a character has been stored in location x40FE)

Page 285, Problem 10.16. (2)

Replace : modified interrupt handler of Exercise 10.6
With : modified interrupt handler of Exercise 10.15

Page 292, Figure 13.14. (1.1,1.2) 4th line of code:

Replace: /* Initial the result variable */

With: /* Initialize the result variable */

Page 294, Section 13.2.3. (1.1) Disregard the last sentence of the second to last paragraph in this section that begins as, "See Problem 15..." The while version of the program behaves just like the do-while version.

Page 296, Section 13.4.1. (1.1,1.2) Series expansion of pi: 4/(2n+1) at the end of the formula should be 4/(2n-1)

Page 307, Problem 13.11. (Solution Manual) The correct answer is:

Page 308, Problem 13.15. (1.1) This problem should be discarded. There is no difference in behavior between the code in Figure 13.10 and Figure 13.16.

Page 332, Problem 14.9. (1.1) Part 2 should read: If the function food takes no arguments, then how many local variables must it have?

Page 344, Problem 15.4. (1.1) The program should echo not only the alphabetic characters, but ALSO the numeric characters AND the space character.

Page 344-345, Problem 15.5. (1.1,1.2) The problem is correct as stated, however, the variable names in the function IsDivisibleBy were incorrectly used as chosen. The parameter "divisor" should instead be "dividend" and the parameter "quotient" should instead be "divisor".

Page 363, Problem 16.9. (1.1,1.2) The function which is defined as "void M()" should be defined instead as "int M()".

Page 384, Section 17.3.5. (1.1,1.2) Line 7: (notice there are two changes)

Replace: either by using work[3] or *(cptr + 4).
With: either by using word[3] or *(cptr + 3).

Page 427, Problem 19.4. (1.1) The printed version of this problem contains an error. It is also quite a challenging problem to solve. An easier (and correct) version of the problem is included below, and the solution for this is provided in the solutions manual.

struct char_rec *back;

};

main()

{

struct char_rec *ptr, pat[MAX+2];

while ((pat[i].ch = getchar( )) ! = '\n') {

ptr[++i].back = ++ptr;

if (i > MAX) break;

}

while (j <= i)

printf("%d ", pat[j++].back - pat);

/* Note the pointer arithmetic here: subtraction of pointers to structures gives the number of structures between addresses, not the number of memory locations */

}

Page 430, Table A.1. (1.1,1.2) Replace xF402 with xFFFF.

Page 448, Appendix A. (1.1) Line -5: Replace 192 with 224

Page 449, Table A.3. (1.1,1.2) The table should read:

x22 PUTS Write a string pointed to by R0 to the console. Each memory location contains one ASCII character.

x24 PUTS.P Write a string pointed to by R0 to the console. Each memory location contains two ASCII characters.

Page 452, Appendix B.1.1. (1.1,1.2) Line -12: Replace 32-bit with 16-bit

Page 474, Figure C.2. (1.1,1.2) The state machine figure fails to illustrate that LEA (state 11) sets the condition codes. This is an error and should be noted that the LEA DOES set the condition codes. Also, the arrow from state 19 to 34 should be labeled with a 0.

Page 480, Appendix C.4. (1.1,1.2)

Line 13: Replace 111000 with 010000

Line 14: Replace 111010 with 010010

Page 481, Appendix C.4. (1.1,1.2)

Line 5: Replace J/111000 with J/010000

Line 8: Replace 111000 with 010000

Line 9: Replace 111010 with 010010

Last updated: 10.09.03 13:32 /mjs