Why are computers byte addressable?

Why are computers byte addressable?

When computers were so costly that they were only or mainly used for science and engineering, word addressing was the obvious mode. As it became cost-effective to use computers for handling text, hardware designers moved to byte addressing.

Are modern computers byte addressable?

Most modern computers are byte-addressable. Each address identifies a single byte (eight bits) of storage. Data larger than a single byte may be stored in a sequence of consecutive addresses. There exist word-addressable computers, where the minimal addressable storage unit is exactly the processor’s word.

What is meant by addressable memory?

Content-addressable memory (CAM) is a special type of computer memory used in certain very-high-speed searching applications. It is also known as associative memory or associative storage and compares input search data against a table of stored data, and returns the address of matching data.

What is the difference between byte addressable and word addressable?

Byte addressable means that every byte has its own unique address and can be accessed. Word addressable means that every word has its own unique address and can be accessed.

What is purpose of Mar?

memory address register (MAR) – holds the address of the current instruction that is to be fetched from memory, or the address in memory to which data is to be transferred.

Why do we need memory alignment?

The CPU can operate on an aligned word of memory atomically, meaning that no other instruction can interrupt that operation. This is critical to the correct operation of many lock-free data structures and other concurrency paradigms.

Why computers have both main memory and secondary memory?

Because the main memory can quickly let the program access data from any random location, but can easily be erased when the computer is turned off. Secondary storage can help keep some of the lost data and can create a backup for important files or programs regardless of the computer power.

What is an addressable unit?

In general it means the smallest data item you can access with a unique address. Some computers have byte-addressable memory which means that each byte of data in memory has a unique address.

Why is MIPs byte-addressable?

for MIPs 32-bit, the main memory has a 32-bit address input bus, each slot in memory holds 8-bit, so each address can refer to 8-bits of memory (which is why its byte addressable); since register size is 32-bit, “words” in main memory start at every 4th byte (so that each word is 4 consecutive slots in memory – 4 * 8 = …

What is a word addressable machine?

In computer architecture, word addressing means that addresses of memory on a computer uniquely identify words of memory. It is usually used in contrast with byte addressing, where addresses uniquely identify bytes. A computer that uses word addressing is sometimes called a word machine.

What does the word addressable means?

1 : able to be addressed : directly accessible addressable registers in a computer. 2 : of or relating to a subscription television system that uses decoders addressable by the system operator.

What are the purposes of control unit?

The control unit controls and monitors communications between the hardware attached to the computer. It controls the input and output of data, checks that signals have been delivered successfully, and makes sure that data goes to the correct place at the correct time.

What is the difference between word addressable and byte addressable?

An eight bit processor like the Intel 8008 addresses eight bits, but as this is the full width of the bus, this is regarded as word addressable. The 386SX, which addresses memory in 8 bit units but can fetch and store it 16 bits at a time, is termed byte addressable.

What is byte addressing in computer architecture?

Byte addressing. Byte addressing refers to hardware architectures which support accessing individual bytes of data rather than only larger units called words, which would be word-addressable. Such computers are sometimes called byte machines (in contrast to word machines ). The basic unit of digital storage is called a bit, storing a single 0 or 1.

What is the size of address bus in bytes?

Addressable memory (in bytes) related to address bus size A 1-bit address bus can address up to two locations (that is 0 and 1). A 2-bit address bus can address 2 2 or 4 locations (that is 00, 01, 10 and 11). A 20-bit address bus can address up to 2 20 addresses (1 MB). A 24-bit address bus can address up to 16 MB.

How many bytes can a 32-bit processor address?

Or consider the 32-bit Pentium processor. Its 32-bit address bus can address 4 billion different items. Using word addressing, a 32-bit address bus could address 4 Gigawords; or 16 Gigabytes using the modern 8-bit byte.