Form Of Dram As Video Memory example essay topic

Computer memory is an area where data is stored on a semi conductor chip. It's a tiny board made of silicon and geranium rather than on some other storage medium, such as hard drive, compact disc or tape cartridge. The data can be stored permanently or temporarily on the chip. In a computer, memory is a necessity, and the more the better.

For the most part, the user has little interaction directly with the memory unless of course you try to open several applications at one time, then you may receive an error message in response. But understanding how memory works, can give you a better understanding how the PC works as a whole. Memory isn't just one single unit. It includes several components working together within the PC. The most commonly known type is RAM which stands for Random Access memory. This is the computers main memory.

RAM is the area of the computer where data is temporarily held while an application or the operating system is using it. Another type of memory known as ROM, Read Only Memory retains data permanently. Rom is an area of memory that contains data that maybe accessed but not altered. Calculators and digital watches contain ROM. In a computer ROM is on a memory chip that either plugs into or is soldered onto the motherboard. Computer contain only a small amount of ROM just enough to support the BIOS (Basic Input / Output System).

The BIOS is a set of instructions that control the computers startup process, activated the hardware components and loads the operating system. Because the ROM chip in a computer only contains the BIOS, it's sometimes referred to as the BIOS ROM. BIOS used to be permanently placed in the ROM by the memory manufacturer, but as time went by it proved to be quite inconvenient especially to manufacturers that needed to upgrade the BIOS. To solve this, several types of PROM (Programmable ROM) were developed.

PROM chips were not inscribed with data during the manufacturing process. These blank chips were sold to computer manufacturers and resellers who use a special piece of hardware called a PROM programmer to burn the chips. There are several different types of PROM, including EPROM (Erasable PROM), EEPROM (Electrically Erasable PROM, and flash memory which is a type of EEPROM. Data contained in these types of PROM can be erased and updated as needed using a PROM programmer or a special software application.

RAM RAM is the type of memory referred to as the main memory. It has the largest area of chip based memory storage in the computer system. All data contained in RAM is held there temporarily until it is no longer needed or the computer is turned off. RAM gets its name from the fact that it is allowed to be accessed randomly. That mean the CPU (Central Processing Unit); is the device that interprets and carries out instructions can access RAM data directly, in a non-linear fashion. The name RAM comes from its comparison with the first forms of computer memory, which stored data in a linear format.

Every PC contains at least two types of RAM: DRAM (Dynamic RAM) and SRAM (Static RAM). Additionally most systems contain some form of peripheral RAM. Video memory is the most popular form of peripheral RAM but many printers contain peripheral RAM. Dynamic RAM is usually what we refer to when talking about RAM. DRAM is one of the most active components in a PC. Almost everything seen on a PC screen is held temporarily in DRAM.

Many PCs sold today come equipped with at least 128 MB of DRAM. In DRAM data exists in an array, which is a type of grid containing thousands of neatly arranged bits of data. The array must be electronically refreshed hundreds of times every second in order to maintain its charge retain its data. if the array loses power, even for one second, all the data it held is erased. That explains why a computer user should use the Save command at every opportunity.

DRAM technology has undergone many changes since the first PC hit the market. During the last six years alone at least half a dozen types of DRAM has had an impact on the market. Every new type of DRAM promises to run faster amd more efficiently than its predecessors. Most systems sold today come equipped with SDRAM (Synchronous DRAM). Originally DRAM was contained on memory chips that were soldered to the motherboard. These chips held only a small amount of DRAM.

An entire system may have contained only about 8 KB or 16 KB, but consumed a relatively large amount of space. But as PCs evolved and DRAM increased it became necessary to find a more efficient means of connecting memory chips the motherboard. The solution came in the form of SIMMs (single inline memory modules), which were either 30 pin or 72 pin expansion cards that plugged into slots the motherboard. Later a 72 pin and a 168 pin DIMM (dual inline memory modules) were developed. DIMMs provide faster data access and more efficient memory storage than SIMMs. Another type of DRAM became available called RDRAM or Rambus DRAM.

This technology is significantly faster than the DRAM on most computers. RDRAM derives its speed from a proprietary signaling technology that allows the memory module to operate at speeds of 800 MHz. (One megahertz equals one million cycles per second). Typical DRAM run at speeds between 66 MHz and 133 MHz. The most popular promoter for DRAM is Intel.

This company produced several chipsets including the popular Intel 820 and 840 specifically for the purpose of supporting RDRAM technology. RDRAM along with an improved version of DRDRAM are stored on in-line memory modules called RIMMs. RIMMs are almost identical to DIMMs except that RIMMs come in 184 pin model. Because RDRAM runs at such a high speed, the RIMMs also include a built in heat shield to protect the memory chips from overheating. Another difference between RIMMs and DIMMs is cost.

You can expect to pay twice as much for a RIMM than a DIMM. RDRAM can be found on higher end Pentium desktops like Gateway and Dell. Static Ram does not need to be continuously refreshed in order to retain data. This makes it faster and more stable than DRAM. However, there is a price for speed and stability so SRAM costs quite a bit more than DRAM. For this reason SRAM is usually found only in L 1 (level 1) and L 2 (level 2) caches which are used for holding areas between the main memory and the CPU.

These caches make up for DRAM deficiencies by holding the most frequently accessed data. On newer systems, the L 1 cache is a memory chip contained within the CPU. Thats why the L 1 cache is often referred to as internal memory. it is also known as internal memory. It is also known as primary cache as it is the first place the CPU looks for data.

The L 2 cache is usually located in a separate chip between the CPU and DRAM and is referred to as external memory. It is also known as the secondary cache because its the second place the CPU looks the data. L 2 cache is larger than L 1 cache. Peripheral Ram as mentioned before include memory found in video cards and printers. This type of RAM temporarily holds data that travels between a peripheral and the rest of the system. Video RAM or VRAM is one of the most common peripheral RAM.

It's usually located on the video card but maybe built into the motherboard on some older systems. VRAM differs for RAM because two devices can access it at the same time. This capability lets VRAM receive data from the CPU or the Graphics accelerator at the same time it transmits data to the monitor. RAM on a video card isn't necessarily VRAM.

Many video cards use some form of DRAM as video memory. Video cards sold typically today contain between 8 MB and 128 MB. For example Leadtek WinFast A 250 Ultra TD, which is a higher end Video card, referenced from the following URL. (web) A good reference for purchasing and comparing prices for video cards is web Printer memory often referred to as printer buffer momentarily holds incoming data until the printer is ready to print it. This lets the CPU perform other tasks without waiting for the printer to print a lengthy print job.

The printer buffer can be anywhere from 4 MB to 8 MB of DRAM. I've explained about the various types of RAM found in a PC. Now I will explain how they work together with the CPU and the storage devices to process and manage data within the PC. Ill briefly explain the components of the PC and how the memory interacts with them. The CPU is like the brain of the PC with its primary function to process, manage and do all the thinking.

It performs calculations, recognizes relationships and makes decisions. But before it can do any of this, it requires some data to work on. This data is kept in three separate places, ROM, RAM, and the computer storage devices. Each has an important role.

ROM provides the most secure and permanent form of data storage in a PC, and is like the human memory that remembers information like how to walk or speak your native language. This data is built into the infrastructure of the PC and cannot be changed easily. Two types of RAM provide the computers with short-term memory. SRAM is like a short-term memory that lets you remember the first half of a sentence so that you can make some sense of the second half.

DRAM on the other hand is like the type of short-term memory that helps you remember where you parked your car or what you need to buy at a store. Either way, the data here can be quickly replaced with something else. Storage devices are like long-term memory holding data for extended periods of time. In a human this type of memory helps you remember significant information such as your name, date of birth or teacher's name. In a PC, the storage devices let you store important documents, financial records and other data you don't want to lose. All forms of computer memory store data as electronic signals or pulses.

Each signal represents a single bit of data. In conventional ROM, the memory chip has built in, permanent signals. In RAM and newer versions of ROM, the signals are established by an electronic charge. ROM can retain data after the electronic charge ends, but RAM cannot. When RAM loses power, the signals that represent the data are lost. The first time memory comes into play in the system is when you turn the power button on of the PC.

The PC is hand-wired to look in the BIOS ROM immediately upon startup. The BIOS activates various components, including the keyboard and disk drives, and initializes the operating system. At that point the operating System takes over. It controls how much DRAM is allocated to each application and to the Operating System. When you open an application the CPU copies the data from the hard drive and, while processing it, it transfers it to DRAM where it resides while the application remains open. The data is placed in a specific location as determined by the OS.

The system bus shuttles data between DRAM, L 1 and L 2 caches, and the CPU. While all this goes on, the CPU continuously transmits display data to the video card. If the video card has a graphic accelerator, the accelerator gathers and processes the data. A small portion of video memory is allocated to assist the accelerator in this task. The rest of the video memory is used as a frame buffer where the display data is organized into individual images before appearing on screen.

The process is similar if you decide to print some data in the print buffer, which holds the data and compiles it into a printable page. When you use the applications Save mode, the data stored in RAM is copied to the selected storage device. When you close the application, the data should clear out of both DRAM and SRAM. Sometimes the data doesn't clean out.

If too much data remains in RAM, the system will lock up unexpectedly. History and Development of RAM Memory has come a long way, not only in quantity, but also in terms of quality and price. There are a few reasons for that. First is that memory must be able to keep up with the processor.

In the early days this wasn't much of a problem as the processor's rate was only about 5 MHz. But due to recent technological developments in CPU's have made the task of keeping up a more difficult thing to do. It took Intel nearly twenty five years to produce a 150 MHz chip, and took them less than two years to produce one less than three times as fast. A PC may contain a processor capable of running at 950 MHz, but if the memory has a maximum capability of 133 MHz, the CPU wont be able to function at its optimum speed. Trying to keep up with the CPU is the reason why so many different versions of DRAM are on the market.

In addition to SDRAM, a very common type of DRAM, many systems sold today may contain DDR SDRAM (Double data rate SDRAM) and RDRAM. Older computers may have used FPM DRAM and EDO DRAM (See glossary at end for definitions). So the development of the CPU has increased the rate of development of the memory required in recent years. But even software developers can be partly blamed or credited for that because software developers have pushed their products to do more and to do it faster and more conveniently for the end user. Looking at the progression of the Operating System indicates how the demand for more has changed personal computing. In 1990, most PC's ran the text based DOS OS.

DOS had very few built in functions and made few demands on a system serving mainly as a platform on which to run computer applications. It was however boring and ugly to use for users especially beginners. Compare that to Windows XP. Windows XP is more than an operating system. It's a communication base, and entertainment center and an office assistant. Not only does it look sharp and supports over 16 million colors, it plays music and motion video.

This type of computer requires a sophisticated computer system and a lot more memory. Multi media capabilities have pushed memory requirements up for all PCs. And all that has increased the price of PCs. Fortunately the price of memory has been on the decline for the past few years, In 1995 one megabyte of memory cost about $25 but in 2002 that much memory can be obtained for less than 50 cents. The reason for the steep price cut is due to over production. Prior to 1995 memory manufacturers could not keep up with the demand.

The price of RAM went up, the cost of production went down, and memory manufacturers made healthy profits. This caused a reaction in the industry. In 1995 several companies built Fabs (laboratories where memory chips are built) to capitalize in the memory market. The average Fab cost $2.5 billion to build and lasted about three to four years before its technology became obsolete. Memory manufacturers had a lot of memory to sell fast to recover its costs. That's easy when the demand is high and supply is low.

But as the market became saturated. The supply of memory exceeded the demand and so the price of memory declined tremendously. The manufacturers who had invested enormous amounts of capital had no choice but to produce even more memory chips to make up for the low prices. This saturated the market even more. As a result the cost per megabyte of memory dropped more than 90% in a two year period, between 1995 and 1997.

For the Future of Memory Since 1997 prices have stabilized and the future is looking good. Systems will continue to come equipped with even greater amounts of DRAM. prices for memory should remain stable as demand remains high. And new memory technologies like DRDRAM and DDR SDRAM should eliminate the gap between processor and memory speed. Soon system memory might make a big leap to the CPU. This could eliminate concerns about speed because the data transfer rate will decrease to almost zero nanoseconds. It might take three to five to even ten years for this to happen, but at some point those memory modules in PCs might become part of history.