What are the advantages and disadvantages of variable length encoding?

What are the advantages and disadvantages of variable length encoding?

Advantages: It easy to provide a large repertoire of opcodes, Addressing can be more flexible, with various combinations of register. Disadvantages: an increase in the complexity of the CPU.

What are the advantages of using variable length instruction format?

One of the advantages of using a variable-length instruction format is that it easy to provide a large repertoire of opcodes, with different opcode lengths. Addressing can be more flexible, with various combinations of register and memory references plus addressing modes.

What is an important disadvantage of variable length instructions?

Disadvantages of variable length instruction format: Processor complexity depends on instruction length. Variable length instruction format does not remove desirability of instruction length which is integrally related to word length.

What is the benefit of having fixed length instructions over variable length instructions?

A minor advantage of fixed length instructions compared to typical variable length encodings is that instruction addresses (and branch offsets) use fewer bits. This has been exploited in some ISAs to provide a small amount of extra storage for mode information.

What are the advantages and disadvantages of using fixed length records?

Fixed Length: Advantage: Simple to calculate the starting byte of each record within the file and starting byte of fields within records. Disadvantage: Wasteful of space when storing variable length data because the max data length must be allocated for every record e.g. Strings.

What are variable length instructions?

x86 instructions are variable-length, which means that common instructions typically have a shorter encoding and so take up less space in instruction cache. Therefore, x86 chips need smaller instruction caches for the same performance. This is very important.

What is the difference between fixed length and variable length?

A fixed length variable is one whose length never varies, whereas a variable one is whose length varies with changes in inputs. The fixed length ensures the fixed length is never variable. A variable-length is one in which the length of each record can vary, depending on what data is stored in the field.

What is a disadvantage of using a variable length column type?

Variable Length: Advantage: Conserves disk space by using just the space needed to hold variable length data. Disadvantage: Expensive to locate specific records within a file or specific fields within records.

What is the disadvantage of a variable length field of a record in a file?

Disadvantages: Not flexible. Hard to change a field length.

What are the advantages of fixed length encoding?

Advantages of fixed-length instructions are given below: It simplifies the process of instruction fetching. The instruction pointer is incremented by a constant amount. The length of the instruction is known in advance.

Which architecture uses variable length of instructions?

VAX is another architecture (popular from the end of the 70’s up to late 80’s) which sported variable length instructions, based on similar principles.

What does variable-length mean?

Variable length refers to anything whose length can vary. For example, in databases, a variable-length field is a field that does not have a fixed length. Instead, the field length varies depending on what data is stored in it.

What are the advantages and disadvantages of variable-length instruction format?

One of the advantages of using a variable-length instruction format is that it easy to provide a large repertoire of opcodes, with different opcode lengths. Addressing can be more flexible, with various combinations of register and memory references plus addressing modes. A disadvantage however is an increase in the complexity of the CPU.

What is the difference between Thumb code and variable length encoding?

It needs more instruction cache than a variable-length encoding does. The ARM solution is to add a second instruction decoder. Thumb code was introduced as a subset of ARM operations. In modern ARM chips, thumb code is extended with the Thumb-2 instruction set, which contains a more powerful subset.

What is the advantage of fixed extent over variable extent?

Fixed extents also gives more control on managing the extents themselves and transferring between environments when needed. The only real advantage of fixed extents over variable extents today, is that the space is pre-allocated and therefore always available to the database.

What are the advantages of using short instructions in C programming?

• It simplifies the function of control unit. • They are fast and show better performance. • It wastes memory which requires padding the shorter instructions so as to make it of fixed length. • The program needs more memory at the time of execution of the instruction and also requires larger time to load from the secondary memory.