Why are there 8 bits in a byte?
Show
Here is a sort of glossary of computer buzzwords you will encounter in computer use: Bit Binary Numbers If you do the same thing with bits that can only be 1 or 0, each position in the list of bits represents some power of two. 1001 means one eight plus no fours plus no twos plus one extra. This is called binary notation. You can convert numbers from binary notation to decimal notation, but you seldom have to. Bytes The largest number you can represent with 8 bits is 11111111, or 255 in decimal notation. Since 00000000 is the smallest, you can represent 256 things with a byte. (Remember, a bite is just a pattern. It can represent a letter or a shade of green.) The bits in a byte have numbers. The rightmost bit is bit 0, and the left hand one is bit 7. Those two bits also have names. The rightmost is the least significant bit or lsb. It is least significant, because changing it has the smallest effect on the value. Which is the msb? (Bytes in larger numbers can also be called least significant and most significant.) Hexadecimal
Numbers Here's a handy table: With three different schemes running around, it's easy to confuse numbers. 1000 can translate to a thousand, eight, or four thousand and ninety six. You have to indicate which system you are using. The fact that you still sometimes see an obsolete system called octal (digits 0-7. You can work it out) adds to the potential for confusion. Hexadecimal numbers can be indicated by writing them 1000hex 1000h or 0x1000. Binary numbers can be written 1000bin . Octal numbers were just written with an extra leading 0. Decimal numbers are not indicated, unless there's some possibility of confusion, such as one in a page of hex numbers. Buss In computer engineering, the concept of a buss has been expanded to mean a group of wires that carries data around the system. There's usually enough wires to handle one to four bytes. The size of these busses has a big effect on the efficiency of the system. A 32 bit buss can handle numbers twice as long (meaning 2 to the 16th bigger) than a 16 bit buss. Serial Data Memory Each member of the group is connected to one wire of the data buss. A group can be instructed by some other wires to copy the state of the buss, or to connect their outputs to the buss, so the buss reflects what's in this group. These other wires are in fact a second buss called the address buss. By manipulating the address buss, the central processor can choose which particular group of transistors (or memory location) to read or modify. The number of wires in the address buss determines how many memory locations it could possibly address. This kind of memory is called RAM for random access memory. Since it depends on transistors to stay on, all data goes away when the power is turned off. Some computers can keep the memory by never really turning off. They have a battery that keeps enough power to the memory transistors that they don't forget. Another kind of memory is called ROM, for read only memory. There are various types of this, but the most common is like an array of fuses. Any that are blown represent a 0. Nothing can change what's in read only memory, so any program or data in there is available as soon as the computer is turned on. Drives Peripheral
devices Parallel Port SCSI SVGA Comm Port Modem Ethernet USB Firewire MIDI
Why do bytes only have 8 bits?The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit of memory in many computer architectures.
What is the significance of 8 bits?8-bit is an early computer hardware device or software program that is capable of transferring eight bits of data at the same time. For example, the Intel 8080 processor, which was one of the first widely used computer processors ran on an 8-bit architecture. Today's computer processors are 64-bit.
Does a byte always contain 8 bits?Yes, a byte is always 8 bits in modern computing.
Why are there 7 bits in a byte?It was common to use 7-bit byte sequences for ASCII text, which gave 5 characters per word and one (usually) unused bit. There were monitor calls (system calls) that accepted strings of 7-bit characters packed in this way. So: at the hardware level, bytes were variable-sized.
|