Computer Architecture

If you order your cheap custom paper from our custom writing service you will receive a perfectly written assignment on Computer Architecture. What we need from you is to provide us with your detailed paper instructions for our experienced writers to follow all of your specific writing requirements. Specify your order details, state the exact number of pages required and our custom writing professionals will deliver the best quality Computer Architecture paper right on time.

Our staff of freelance writers includes over 120 experts proficient in Computer Architecture, therefore you can rest assured that your assignment will be handled by only top rated specialists. Order your Computer Architecture paper at affordable prices with cheap custom writing service!

Computer Architecture

Outcome

John Lennon

1.Buy custom Computer Architecture term paper

Over the years the microprocessor has developed in various areas. Each processor development has a different design, wiring and a different instruction set. The main developments which has improved the functionality of the microprocessor are-

Bus width

The Address bus opens an address location, the width of the address bus determines how many memory locations can be accessed at any given time (how much memory you can address to where n = bus width) for example pieces of information being simultaneously transferred, is the equivalent to bit bus width. The wider the bus width the more information can be transferred from CPU to memory at the same time. When looking at an Early Intel chip such as the 8080, which had an address bus width of 8bits, which means it could only access 1Meg of memory at a time, and then compare that to the P III, which has an address bus width of 6 bits and can access up to 64 Gigabytes of memory at once, we can see that the developments in processors has had a significant effect on overall system performance.

The Data bus is used to transfer data from the CPU to RAM and vice versa, clearly data bus width (16bit, bit, 64bit) defines the performance of the CPU in that the more data that can be transferred at the same time, the better the performance. The control bus instructs a memory location to read/write dependent on the CPU's instructions

The instruction set is a list of commands that a processor execute (usually written in assembly language). Most computers have four main types of instructions,

• Input and output of data (in, out).

• Arithmetic and logic operations (add, subtract, and, or, not).

• Instruction sequence changing (branch, jump, compare).

• Data transfer (move, load, store).

As instruction sets increased with processor development, computers had far greater functionality. As the instruction set developed so did the software to utilise the new features. There is no forward compatibility with reference to instruction sets, this means that when a processor is specified in the hardware requirements( 486) this is the minimum processor acceptable. When the minimum is specified it may not be that earlier processors are not fast enough, the problem may be that the earlier processor may not have the necessary instructions, which may be called for from the software program. An example may be a program with a minimum hardware requirement of a Pentium call processor, may not run on a 486 processor.

Clock speed

The clock speed is measured in cycles/second (Hz) and could be described as ticks, as processors developed from 8086, 80486 and then Pentium and upwards, the clock speed rose sharply and gave more functionality for the CPU. The internal architecture of a CPU has as much to do with a CPUs performance as the clock speed, so two CPUs with the same clock speed will not necessarily perform equally. Whereas an Intel 8086 microprocessor requires 0 cycles to multiply two numbers, an Intel 80486 or later processor can perform the same calculation in a single clock tick. (Note that clock tick here refers to the systems clock, which runs at 66 MHz for all PCs.) These newer processors, therefore, would be 0 times faster than the older processors even if their clock speeds were the same. The chart below shows how the Intel microprocessor has developed.

Product clock speed Data bus Address bus Accessible memory

8080 MHz 8bit 8bit 1meg

8086 10MHz 16bit 0bit 1meg

8088 10MHz 8bit 0bit 1meg

8086 1MHz 16bit 4bit 16meg

8086 40MHz bit bit 4Gb

80486 100MHz bit bit 4Gb

Pentium MHz 64bit bit 4Gb

P 450MHz 64bit 6bit 64Gb

P 1000MHz 64bit 6bit 64Gb

.

RAM Random access memory, a type of computer memory that can be accessed randomly; that is, any byte of memory can be accessed without touching the preceding bytes. RAM is the most common type of memory found in computers and other devices, such as printers.

There are two basic types of RAM

Static RAM (SRAM)

Dynamic RAM (DRAM)

DRAM comes in various types

FPM (Fast Page Mode)

ECC (Error Correcting Code)

EDO (Extended Data Output)

SDRAM (Synchronous Dynamic RAM)

Static and Dynamic RAM types, differ in the technology they use to hold data, dynamic RAM being the more common type. Dynamic RAM needs to be refreshed thousands of times per second while static RAM's contents are maintained by a small battery on the motherboard. Static RAM holds all of the settings which are machine specific, it is commonly referred to as CMOS (complimentary metal oxide semiconductor), where it not for static RAM the machine would have to self diagnose and auto detect every time it was switched on. Static RAM does not need to be refreshed, which makes it faster; but it is also more expensive and physically about 4 times larger than dynamic RAM.

Dynamic RAM (DRAM) is a type of physical memory used in most personal computers. The term dynamic indicates that the memory must be constantly refreshed

(Reenergized) or it will lose its contents; this is done by applying a refresh pulse (00/second to maintain the contents), which is held in capacitors, which are also being constantly refreshed. DRAM is the component which has the greatest affect on overall system performance because one of the major interactions inside a computer is between DRAM and CPU, for example if you have insufficient RAM in a system you will experience a massive fall off in performance. Both types of RAM are volatile, meaning that they lose their contents when the power is turned off. RAM speed is measured in nS (nano seconds 10 to the power minus nine). The fewer the nS, the faster the RAM access time.

ROM (read-only memory) refers to special memory used to store programs that boot the computer and perform diagnostics, in a computer the ROM chip holds the BIOS (Basic Input Output System) in memory so that when the computer boots up it reads the BIOS from the ROM. Most personal computers have a small amount of ROM (a few thousand bytes) that is placed on the small chip (EEPROM, electrically erasable programmable read only memory) on the motherboard. ROM speed is also measured in nano seconds (nS) the fewer nS the faster the ROM. Here is a table, which illustrates ROM speed, relative to clock speed.

Clock speed Time per clock tick

MHz ns

0 50

5 40

0

50 0

66 15

100 10

1 6

In fact, both types of memory (ROM and RAM) allow random access. To be precise, therefore, RAM should be referred to as read/write RAM and ROM as read-only RAM. The access speed is also a factor in the performance of a computer while DRAM supports access times of about 60 nanoseconds, SRAM can give access times as low as 6 nanoseconds. In addition, its cycle time is much shorter than that of DRAM because it does not need to pause between accesses. Unfortunately, it is also much more expensive to produce than DRAM. Due to its high cost, SRAM is often used only as a memory cache.

A variation of a ROM is a PROM (programmable read-only memory). PROMs

are manufactured as blank chips on which data can be written with a special device called a PROM programmer .

EPROM

Acronym for erasable programmable read-only memory, EPROM is a special type of memory that retains its contents until it is exposed to ultraviolet light. The ultraviolet light clears its contents, making it possible to reprogram the memory. To write to and erase an EPROM, you need a special device called a PROM programmer or PROM burner.

An EPROM differs from a PROM in that a PROM can be written to only once and cannot be erased. EPROM's are used widely in personal computers because they enable the manufacturer to change the contents of the PROM before the computer is actually shipped. This means that bugs can be removed and new versions installed shortly before delivery.

Addressing

Some machine language instructions are made up of two or more numbers (the processor can only complete the task, once all of the instructions have been received).

The first number in any instruction is called the operation code (op-code); the op-code gives the processor the following information

• The instruction length (tells the control unit whether it has the entire instruction.

• The addressing mode (how to get the data that the instruction may require).

• The operation (what to do with the data.

The numbers that follow the op-code are called operands. The addressing mode tells the processor how to use the operands to get any data that the instruction may require

Main Addressing modes

There are five main types of addressing

 Registered addressing where the data is copied from one register into another.

 Immediate addressing names the actual source address within the instruction.

 Direct addressing names the address the contents are being placed into.

 Indirect addressing is where the address is a memory location that contains the data.

 Indexed addressing this is where a set of instructions are held in memory and sequentially fetched to complete an operation.

.

A normal parallel port (LPT1) has registers -

• Data register( 7816), which is used to send characters out to the printer (pins - on computer end of printer cable).

• Print control register (7A16) Which is used to send control information out to the printer (pins 1,14,16,17 on computer end of printer cable).

• Print status register (716) Which is used to store printer information coming in from the printer (pins10, 11, 1, 1, 15 on computer end of printer cable).

In parallel transmission, the data port has eight separate wires connecting the computer to the external device. There is a separate pin in the socket for each data wire, plus other pins for the control information. Five volts on a wire represents logic 1, while zero volts represents logic 0. In this way, an entire byte can be transmitted at a time. There is a problem sending transmissions over long distances, because each wire has different characteristics, there will be different times taken for data to pass down each wire. This means that over a long distance, the individual bits that comprise a particular byte may not all arrive at the destination at the same time, although they where transmitted simultaneously. This effect is known as "skew" and is why parallel transmissions (printer cables) should be restricted to short cables up to two metres in length.

The printer cable comprises of a 6-pin amphenol plug at the printer end, this connects with the printer's centronic socket, and the plug at the computer end is a 5 pin male D-type connector.

Print process

• Place the data in the data register to feed the external data lines

• Pulse the strobe (pin 1 on printer cable) line low. This should energise the printer end which should result in the printer reading the data off the data lines and switching it's own busy line high.

• Check the busy line (pin 11 on printer cable), when the printer is ready to receive the next character, it will switch it's busy line low again.

• When the busy line goes low repeat the process.

In other systems the printer informs the PC that the data is received by bringing the Acknowledge line low (pin 10 on printer cable).

4.

Devices Interface

Hard disk serial-parallel

Mouse serial

Printer. Parallel

5.

DIGITAL

Digital describes any system based on discontinuous data or events. Computers are digital machines because at their most basic level they can distinguish between just two values, 0 and 1, or off and on. There is no simple way to represent all the values in between, such as 0.5. All data that a computer processes must be encoded digitally, as a series of zeroes and ones. The principal feature of analogue representations is that they are continuous. An analogue transmission is in the form of a constantly varying wave (volts, decibels db). The PSTN is only capable of transmitting data in analogue form.

A modem (modulator-demodulator) is a device that enables a computer to transmit data over telephone lines. Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of analogue waves. A modem converts between these two forms.

To be able to send a signal over an analogue modem the signal must firstly be converted from parallel (several bits are transmitted concurrently) to serial (transmitting data one bit at a time). A chip called "UART" (Universal Asynchronous Receiver Transmitter) carries out this conversion (parallel format from the bus is converted into a stream of bits that are sent sequentially along the cable), and then from digital to analogue (modulation). The analogue signal is then sent via the modem over the PSTN to its destination. Once the destination is reached the analogue signal is then converted back to digital and finally back to parallel (demodulation).

When using a Network interface card (NIC) the diagram would look like,

If devices require to communicate, voltage levels must be standardised. The Institute of Electrical and Electronic Engineers (IEEE) define these levels. It may be that in order to communicate between devices, some signal conditioning (for example voltage regulation) needs to take place.

Please note that this sample paper on Computer Architecture is for your review only. In order to eliminate any of the plagiarism issues, it is highly recommended that you do not use it for you own writing purposes. In case you experience difficulties with writing a well structured and accurately composed paper on Computer Architecture, we are here to assist you. Your cheap college papers on Computer Architecture will be written from scratch, so you do not have to worry about its originality.

Order your authentic assignment from cheap custom writing service and you will be amazed at how easy it is to complete a quality custom paper within the shortest time possible!