History of computer hardware
Reference Links -> https://www.cnblogs.com/Dominic-Ji/articles/10987788.html
Computer hardware
Computer divided into five components are: a controller, the arithmetic unit, memory, input and output devices. Wherein the controller is a computer operator + a central processing unit (CPU), equivalent to the human brain.
Controller
Command system of the computer. Liezi such as: brain commanding the operation of the body organs, but the brain does not act arbitrarily command of the body, the brain only after receiving instruction will control the body action
Operator
Arithmetic operation is a computer system. In addition to the command of the brain, all the time still in operation. That is achieved arithmetic and logic operations.
Operator + = control computer central processing unit CPU
The Liezi:
eating flow examples
1. When you eat, the brain will accept instructions to eat, after translating instructions into action (controller) you need to make the body
2. If you eat Western food, use a spoon; if you eat Chinese food, use chopsticks (operator)
Memory
The second important thing is the computer stores, everyone obscenity storage: fast (so cpu waiting delay memory would be lower) + capacity + cheap. Then while both the three is impossible, so we had the following handled differently
Layer 5 minutes
Register cache memory disk tape
I.e. L1 cache register:
Manufactured by the same material and cpu, cpu as fast and thus cpu access it without delay, typical capacity is: 32 * 32 cpu is 32, 64 in the cpu is 64 * 64, the capacity in both cases all <1KB.
I.e. L2 cache Cache:
The main cache access is controlled by hardware, in memory in accordance with a cache line is 64 bytes 0 to 127 lines of row 1 0,64. . .
Cache is hit, you must access the memory, it will take significant time cost. Since the cache is expensive, so its limited size, some machines have two or even three cache, cache before each level slower than a large but easy.
RAM***
Further down is a layer of main memory, which was the main system memory, main memory commonly referred to as random access memory RAM, is what we usually refer to the memory capacity has been rising, all can not be found in the cache, will to find the main memory, the main memory is a volatile memory, the data disappears after the all-off
Disk
A low speed disk reason it is a mechanical device because
each of the heads can read a few new ones region, called tracks
the position of the arm so that a Godin track together, form a cylinder
of each track into a number of sectors designated a typical value of the sector is 512 bytes
of data are stored in a section of the sector, i.e., the short track circle circle, a piece of data read from the disk seek and latency time to go through
Virtual Memory:
Many computer support virtual memory mechanism that allows a computer to run programs larger than the physical memory, the method is being used by the program execution to take into memory, and the execution of the program no need to put a piece of local disk, this place becomes a virtual memory, become in linux swap, this mechanism is that the core flash memory mapped address, a member responsible for the cpu, memory management unit becomes (memory management unit MMU)
PS: switching from one program to another program, context switching becomes (context switch), the cache and MMU appears to enhance the performance of the system, especially in a context switch
magnetic tape
At the same price the hard disk has a higher storage capacity than, although the speed is lower than the disk, but because of its large capacity, when the earthquake fire flood mobility and other characteristics, often used to make backups. (Common in large-scale database systems)
Input and output devices
1, the input device
task input device is programmed to people and raw data to the computer program to go, and convert them into computer memory and can be identified by way of information received.
2, the output device
task output device is the result of processing in a computer or other device sends a form acceptable to the computer.
The most common output device is a printer and a display. Secondary memory may also be seen as an output device. Further, a digital to analog (D / A) conversion means also an output device.
bus
Structure four bars in use for many years in a small computer and also used in the early IBM PC in. However, with faster and faster processors and memory, a single bus is difficult to handle the bus traffic, so there is a multi-bus mode map, they deal with I / O devices and the memory are cpu to a faster speed.
Northbridge i.e., PCI bridge: high-speed devices are connected
Southbridge i.e. ISA bridge: slow devices connected to
power (Power) == heart: all the components to be operational, have to have sufficient power supply down. It's like the heart, as if the heart is not beating, people belch fart, if the computer is no power, that is a bunch of garbage, what role did not.
Computer startup process
A basic input output program on the computer's motherboard (Basic Input Output system)
BIOS is equivalent to a small operating system, which has the underlying I / O software, including a keyboard read, write screen, disk I / O, the program stored in a non-volatile flash RAM.
Startup process
1. Power on the computer
2.BIOS began to run, hardware detection: cpu, memory, hard drives, etc.
3.BIOS read parameters in the CMOS memory, the boot device select
4. Read the boot device from the contents of the first sector (MBR master boot record 512 bytes, 446 of the front guide information, the partition information 64, the last two bits of flag)
The partition information reading module bootloader boot loader, the operating system boot
6. The operating system then asks BIOS, to obtain configuration information. For each device, the system checks its device driver exists, and if not, the system will require the user according to the device driver. Once you have all of the device drivers, they will be transferred to the operating system kernel. Then about the initial form (such as process table), through the process that you need, and start the login program or GUI on each terminal