Crucial memory chips
Who would have thought that a pile of sand would one day become the greatest value added product in the world. Basically any device that uses electricity and is capable of being programmed or customized to do any function has a chip inside it. Anything from washing machines, dishwashers, automobile dashboard controls, traffic light controllers, to computers and automatic testing instruments, to space shuttles, computer chip technology is indispensable. Crucial memory chips can be simple or complicated .Microprocessor is the most smart, complex and revolutionary chip that can execute hundreds of millions of instruction per second.
What are computer chips:
Crucial memory chips are small units that are capable of storing computer memory and can also be used in microprocessors for logic circuitry. They are generally made of a semi conducting material which is usually silicon and an integrated circuit is embedded on it. These chips are electronic devices and con contain millions of electronic components like transistors etc. The transistors, the key component, are nothing but electronic switches. They can create logical circuits that have decision making power and can solve arithmetic problems. With the help of polysilicon and aluminium wiring, the transistors are then interconnected. These chips can be placed on printed circuit boards which are electronic boards. A typical chip has the size of less than th square inches.
After the invention of the transistor, integrated circuits appeared on the scene at the end of the 1950s; an entire circuit consisting of several transistors, diodes, and resistors could be designed on a single chip. In the early 1960s, logic gates known as the 7400 series were commonly available ICs, and the technology of integrating the circuits of a logic gate on a single chip became known as small scale integration (SSI).As semiconductor technology advanced, more than 100 gates were fabricated on one chip; this was called medium scale integration (MSI). Within a few years, it was possible to fabricate more than 1000 gates on a single chip; this came to be known as large scale integration (LSI). Now we are in the era of very large scale integration (VLSI) and super large scale integration (SLSI).
How are these chips made:
Silicon is the key material for making Crucial memory chips. The silicon is first grown as a single crystal and the seed is then dipped in molten silicon to form silicon cylinders. These silicon cylinders are then sawed to form silicon wafers of desired size. The first layer of silicon dioxide is then grown on the wafer by exposing to heat. A material called photo resist is then coated on the wafer. This material is soluble in ultraviolet light. A patterned mask is then inscribed in the wafer and then wafer is then exposed to UV light. The unmasked areas are attacked by the light to form a gooey layer of photo resist which is dissolved by using a solvent. This process is known as photolithography. The etching process follows removing the photo resist and leaving ridges of silicon dioxide on the wafer base. A second layer can be then prepared by growing a thin layer of silicon dioxide followed by a layer of polysilicon and another layer of photo resist. The photolithography results in ridges of polysilicon and silicon dioxide.
Doping is then done by bombarding the exposed areas of wafer with ions to build transistors and other electronic parts on the wafer surface. At least two layers are required to form a transistor. This process is known as ion implantation. The layering and masking processes are then repeated to create windows for electrical connections. Windows are then filled with metallic atoms after which masking and etching processes are repeated. This leaves strips of metals for electrical connections.
The wafer is then cut with diamond saw into a number of chips. Each chip is then mounted in an electronic package to protect it and the chip is ready to use.
The surface of a Crucial memory chips has reflective properties and when light falls on it, it is reflected and refracted and different colors are produced depending on the design of the chip, the technology and the lens used the magnification, the lighting and the viewing angle. Most of the times the colour reflected is white but it maybe other primary colors like red, yellow, green or other unique colors as well.
Computer chips: CPU, ROM, RAM
CPU: The Central processing unit (CPU) functions like a brain coordinating the activities of the other devices. The CPU is the primary and central player in communicating with devices such as memory, input and output. It may reside on a single chip or number of chips. When CPU is built on a single chip, it is known as microprocessor. The chip is enclosed in a plastic container and is a mesh or a grid of silicon wires. The CPU is responsible for the arithmetic and logic operations and also has the control unit.
ROM: Read Only Memory
These were the first computer chips developed. A ROM chip typically contains frozen information and is independent of the disks. This might be word processing, BASIC or general screen codes. It is a non volatile memory; it retains the stored information even if the power is turned off. The memory is used for programs and data that need not be altered.
Masked ROM:
In this ROM, a pattern is permanently recorded by the masking and metallization process. Memory manufacturers are generally equipped to do this process. It is an expensive and a specialized process, but economical for large production quantities.
PROM: Programmable Read Only Memory
This memory chip has nichrome or polysilicon wires arranged in a matrix;
these wires can be functionally viewed as diodes or fuses. A glass window on the top of the chip allowed a laser beam to program it once the chip was built. This memory can be programmed by the user to do specific jobs. So the industry got this chip which could be plugged in the computer to perform a specific task.
EPROM: Erasable Programmable Read Only Memory
The Industry then needed a chip that could be programmed, erased and then reprogrammed. All the information is stored by using an EPROM Programmer. All the information can be erased by exposing the chip to ultraviolet light through its quartz window. And the chip can be reprogrammed. Because the chip can be reused many times, this memory is ideally suited for product development, experimental projects and college laboratories.
EEPROM: Electrically erasable PROM
The industries then didnt want to pay all the time to erase the memory and when it took so long. So, EEPROM came into picture. This memory includes a chip erase mode whereby the entire chip could be erased in 10 ms compared to 15-20 minutes in EPROM. It is often referred to as Flash memory (the only difference between the EEPROM and the flash memory is the erasure procedure: EEPROM can be erased at the register level, but the flash memory must be erased either in its entirety or at the sector level), USB or chip memory, stick memory etc. When the power is on, the chip can be programmed. The data remains in the chip when the power is turned off. The data can be transferred by putting back the power on and then can be electronically erased. EEROMs will replace HD, FD and CDs on our PCs and digital cameras.
RAM: Random Access Memory
These chips are fully addressable. Each and every byte of data is stored at a specific hexadecimal address in the chip and can be retrieved from that address. It is used primarily for information that is likely to be altered, such as writing programs or receiving data. This chip doesnt come with any instructions in it. When power is turned on the data can be moved in and out of the chip. When power is turned off, all the contents are destroyed. The RAM chip is Volatile and data has to be saved to an auxiliary storage device such as a floppy drive, hard drive, CD or EEROM.
RAM chips are used to temporally store data and make up main memory. It maybe referred to as short term memory in human brain. The size of the prime memory, such as 512 K or 8 M, determines how large a program the system can process. All main memory is comprised of RAM chips.
Following are the different types of RAM:
1. SIMM: single in line memory module
2. DIMM: dual in line memory module
3.DRAM: dynamic RAM
4.FPM RAM: fast page mode RAM
5. EDO RAM: extended data out RAM
6. BEDO RAM: burst extended data out RAM
7. SDRAM: synchronous dynamic RAM
8. SRAM: static RAM
9. Async SRAM: asynchronous RAM
10. PB SRAM: pipeline burst RAM
11. VRAM: video RAM
12. WRAM: windows RAM
13. SG RAM: synchronous graphics RAM
14. CMOS RAM: Composite Metal oxide silicon chip- The CMOS chip contains the set up data.
PACKAGES
Generally, chips come in three most common packages:
1. DIPs (Dual in line packages): They are traditional chips and have around 8-40 legs evenly divided into two rows.
2. PGAs (pin-grid arrays): Here the pins are arranged in concentric squares.
3. SIPs (single in line packages): These chips have just one row of legs in a straight line.
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