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Questions and Answers

What is the purpose of logical operations in programming languages and instruction set architectures?

To manage memory more efficiently

To control the flow of execution in programs

To simplify the packing and unpacking of bits into words (correct)

To perform calculations with floating-point numbers

How can the NOT operation be implemented according to the content?

Using XOR with one operand being all ones (correct)

Using AND with a zero operand

Using OR with a one operand

Using shifting operations on the bits

What example is used to illustrate operations on characters within a word?

Processing of 16-bit words

Examining 8-bit characters (correct)

Manipulating hexadecimal values

Performing arithmetic operations on bytes

Which of the following languages are shown in the figure for logical operations?

C, Java, and RISC-V Signup and view all the answers

What historical figure is referenced in relation to logical operations?

Lewis Carroll Signup and view all the answers

What does biased notation achieve in numerical representation?

It ensures that all numerical representations are non-negative. Signup and view all the answers

In RISC-V, how are instruction fields typically referred to?

By their numerical order. Signup and view all the answers

What binary value typically represents zero in biased notation?

10...00two Signup and view all the answers

Which of the following correctly identifies a segment of an instruction in RISC-V?

A section of the instruction that specifies registers. Signup and view all the answers

What is the decimal representation of the register used in the RISC-V instruction 'add x9, x20, x21' for register x21?

21 Signup and view all the answers

What is the significance of the fields containing 0, 0, and 51 in the instruction 'add x9, x20, x21'?

They specify which registers to add. Signup and view all the answers

What is a likely reason for representing instructions as series of electronic signals?

To facilitate faster processing by computers. Signup and view all the answers

What kind of numerical representation does biased notation utilize for positive values?

11...11two Signup and view all the answers

What is the primary method to find the negative equivalent of a one’s complement representation?

Invert each bit of the number Signup and view all the answers

Which statement accurately describes one’s complement compared to two’s complement?

One’s complement results in two different representations of zero. Signup and view all the answers

Why did one’s complement see use in early scientific computers?

It balanced positive and negative representations effectively. Signup and view all the answers

What is the relationship between the various representations discussed?

Two’s complement is a more efficient method than one’s complement. Signup and view all the answers

What does the notation 10 … 000two represent in one’s complement?

The most negative value Signup and view all the answers

How does the negation operation in one’s complement compare to two’s complement?

One’s complement requires an extra step to subtract a number. Signup and view all the answers

What is the most significant characteristic of biased notation?

It incorporates a bias to alter the representation. Signup and view all the answers

What is the result of performing a one’s complement negation on a number?

Flipping the bits of the number Signup and view all the answers

What is the purpose of the 12-bit immediate in the I-type instruction format?

It acts as a byte offset for load instructions. Signup and view all the answers

What principle of hardware design is highlighted by the RISC-V designers?

Good design demands good compromises. Signup and view all the answers

Which fields are included in the I-type instruction format?

immediate, rs1, funct3, rd, opcode Signup and view all the answers

What does the 'lw' instruction signify in the provided example?

Load word from memory into a register. Signup and view all the answers

How many bits are used for the rs1 field in the I-type format?

5 bits Signup and view all the answers

What limit does the 12-bit immediate in the I-type format impose on its value?

Values from −2048 to 2047 Signup and view all the answers

What distinguishes the S-type instruction format from the I-type format?

S-type splits the immediate into two fields. Signup and view all the answers

What is the maximum range of bytes that the I-type load instructions can access?

±2048 bytes Signup and view all the answers

What is the primary purpose of the immediate field in RISC-V instructions?

To represent a two’s complement integer Signup and view all the answers

Which of the following instructions is not available in RISC-V?

subi Signup and view all the answers

In the assembly language, what does the assembler generate when the programmer writes 'add'?

The correct opcode and instruction format depending on operand types Signup and view all the answers

How does the design principle of smaller instructions affect register usage?

It limits the number of registers to minimize instruction size Signup and view all the answers

Why do RISC-V instructions maintain the same size?

To allow easy decoding of instruction formats Signup and view all the answers

Which parts of RISC-V machine language are summarized in the provided content?

Opcode definitions and instruction types Signup and view all the answers

What is the role of funct3 in RISC-V instructions?

It determines the type of operation to perform Signup and view all the answers

What is a limitation imposed on the immediate field due to using two’s complement representation?

It limits the value range to less than 16 bits Signup and view all the answers

Study Notes

Two's and One's Complement Representations

Two's complement allows representation of signed integers, with the rule that the sum of a number and its two's complement equals (2^n).
The formula for negation in two's complement: (2^n - x).
One's complement represents negative values by inverting each bit (0 to 1, 1 to 0).
One's complement has two representations of zero: positive (00…00) and negative (11…11).
The most negative value in one's complement represents (-2,147,483,647).
Both one's and two's complement systems allow an equal number of positive and negative values.

Biased Notation

Biased notation favors non-negative representations by adjusting numbers with a bias.
In biased representation, 00…000 is the most negative value, while 11…11 represents the most positive value, 0 typically being 10…00.

Computer Instruction Representation

Instructions in computers are stored as electronic signals, organized in a sequence of numbers.
Each part of an instruction is termed a field. In RISC-V, fields are used to define operations and operands.

RISC-V Instruction Formats

RISC-V instructions are categorized mainly into R-type and I-type.
R-type is for operations between registers, while I-type includes arithmetic with one constant operand.
The I-type format features:
- 12-bit immediate (two's complement)
- 5-bit source register (rs1)
- 3-bit function (funct3)
- 5-bit destination register (rd)
- 7-bit opcode

Examples of RISC-V Instructions

Example:
- add x9, x20, x21 is represented in decimal as: 0, 21, 20, 0, 9, 51.
The instruction lw x9, 32(x22) is broken down into its respective fields:
- rs1 = 22, immediate = 32, rd = 9.

Design Principles of RISC-V

A key design principle states that good design requires good compromises; maintaining equal instruction length leads to distinct formats for different instructions.
RISC-V prioritizes keeping all instructions uniform, which creates limitations on the number of registers without increasing complexity.

Instruction Types in RISC-V

S-type format is used for store instructions, which requires both source registers and an immediate value for addressing.
The S-type format segments the immediate field into upper and lower parts to accommodate addressing needs effectively.

Conclusion

Logical operations extend the capability of programming languages to handle bits within a word, including packing and unpacking of bits.
Instructions such as NOT in RISC-V can be implemented using XOR with an operand of all ones.

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Description

Explore the intricacies of two's complement, one's complement, and biased notation in computer systems. This quiz will test your knowledge on how these representations work and their implications for signed integers. Understand how different systems affect the representation of numbers in computing.

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