Assignment # 6 Input And Output Devices

Input devices

There are many input formats which enable us to gather up and collect information, and enter data and instructions into the computer.

Input devices can be manual or automatic.

Manual input devices include:

Keyboard - including concept keyboard. This is a flat board that contains a grid of buttons. Each button can be programmed to follow instructions. An overlay sheet is placed on the grid with an explanation for each button. They are used in primary schools with young children. Many modern fast food restaurants have overlays with either a description or picture of the meals that are available to make ordering easier.

Mouse

Tracker ball

Joystick

Light pen

Digital camera - this allows you to take pictures and to store a digital photographic image that can be read by a computer. You can then transfer the images directly from your camera on to your computer.

Microphone - A microphone is a device to input sound information and can be used with a voice recognition system which processes the information. This can be used with a word processing program to enter text. It can also be used as part of security systems - only certain digitally stored voices will gain access.

Touch screen - this is a special type of VDU, which has a grid of light beams or fine wires criss-crossing the screen. When the screen is touched (usually to choose an on-screen option), the computer senses where you have pressed. The information is stored on the computer and the touch screen is simply an interface. Touch screens have the benefit of being very robust and easy to operate and reprogram, hence why they are used in public places.

Video digitiser - this takes an image from a video camera or television and converts it so that it can be used by, and stored on, a computer. Video sequences captured using a video digitiser are often used in multimedia presentations.

Graphics tablet

This consists of a flat pad (the tablet) on which the user draws with a special pen. As the user draws on the pad the image is created on the screen. Using a graphics tablet a designer can produce very accurate on-screen drawings.

Scanner - these are a cheap and common way of getting images into a computer. They can also be used with OCR (Optical Character Recognition) software to scan in text.

Automatic input devices include:

Sensors (see the Revision Bite on computer control)

Barcode reader

Barcodes are different groups of vertical bars that can be read by a barcode reader. Barcodes are printed on nearly every product that you can buy. Shops use barcodes because they enable the shops to maintain their stock control system. The barcode contains the product details such as product name, size, manufacturer, country of origin. The price is looked up from the shop's database. When the bar code is scanned, the shop's stock is automatically reduced by one.

MICR (Magnetic Ink Character Reader) - magnetic ink characters are the strange looking numbers that appear at the bottom of cheques. Banks use MICR to read the numbers from the bottom of cheques to obtain data such as account numbers and bank sort codes. This particular font is used because it is easy for a machine to discriminate between characters. The ink is magnetised because it makes it immune to creases or dirty marks.

Magnetic strip (or stripe) reader

Magnetic stripes are built into many plastic cards such as cheque guarantee cards, cash-point cards and personal identity cards. The magnetic strip on the back of the card can hold the personal details of the card owner and, with the necessary PIN, will allow access to secure information e.g. bank account details. Data stored on the strip is scanned and input into a computer system by a magnetic stripe reader.

OMR (Optical Mark Reader) - this reads marks made by pencil on a printed form into the computer. OMR systems are suited to reading pre-printed forms and check-boxes such as National Lottery number selection sheets and multiple-choice exam papers.

Output devices

Common output formats are printed-paper, saved disk file, sound, video and on-screen documents. They are all of those things that let your computer 'talk' back to you and present information. Examples of devices for these formats are:

Monitors or Visual Display Units (VDUs)

These are the most common output device and include:

• Desktop monitors which are also known as Cathode Ray Tube (CRT)
• Liquid Crystal Displays (LCD) which are also known as Thin Film Transistors (TFT)

Printers

• Laser printers produce a very high quality output, are very quiet and very fast. Laser colour printers are quite expensive to buy.
• Ink-jet printers offer black and white or colour printing with reduced levels of quality and speed. Colour ink jet printers are cheaper to buy than colour laser printers.
• Dot-matrix printers are not so common today. They are comparatively noisy and low quality but are cheap to run and are used when carbon copies or duplicates need to be made, such as for wage slips. Also, they are useful in dirty environments such as a garage because they are much sturdier than the other two types of printer.

Plotters

A plotter can be used to produce high quality, accurate, A3 size or bigger drawings. They are usually used for Computer Aided Design (CAD) and Computer Aided Manufacture (CAM) applications such as printing out plans for houses or car parts.

Other devices

• Speakers
• LCD projectors

Output can also be in the form of instructions to a device such as a robot arm.

References

http://www.bbc.co.uk/schools/gcsebitesize/ict/hardware/0inputandoutputdevicesrev4.shtml

http://www.tpub.com/neets/book22/92e.htm

COMP 372 Assgn. # 5 Internal Circuit of 6810 Microprocessor

The MCM6810, a 128 x 8 chip designed by Motorola is used with its 6800 series processors. This means it stores 128 bytes at addresses from $00 to $7F. If you put any address on the 7 address pins, then the corresponding data appears on the 8 data pins. The time from a change of address to the appearance of the corresponding data is called the access time of the memory. Actually, it is the maximum access time, since each address has, in general, a different access time depending on where it is in the memory array. An access time of 450 ns was appropriate to processors with a 1 μs cycle time, assuming that the proper address would appear midway in the cycle, and the data would be read or written at the end of the cycle.

Since the data pins are connected to the processor's data bus, they must be put into a high-impedance state at all times except when the processor expects them to drive the bus during a read cycle. There are two control lines for the memory chip, the chip select (CS) and the read-write (RW) lines. When RW is high, data appears when CS is active. The 6810 has six CS pins, four active low and two active high. All must be active to say that CS is active.

When RW is low, CS has a different function. Instead of activating the data outputs, it strobes the data on the data bus into the current address on the trailing edge of its pulse. Different memory chips may work in different ways, but something like this occurs in any case. This happens to be the way the 6810 works.

When the 6810 is connected to the processor in the normal way, the RW line is connected to the R/W signal of the processor, which takes its proper value at the start of the cycle. CS is active during φ₂, which is the clock signal produced by the processor that is high during the last half of the bus cycle. If the 6810 were the only thing on the bus (and it will be for our initial test) one can simply use φ₂ as CS. In a more general case, CS will combine both φ₂ and an address decode depending on the current address output by the processor. Different devices on the bus will have different address decodes.

The Internal Structure

References

http://mysite.du.edu/~jcalvert/tech/6504.htm

http://www.datasheetarchive.com/preview/441555.html

COMP 372 Assgn. # 4 Role Of Microprocessor in Computer

The simplified model of a microprocessor consists of five parts, which are:

Arithmetic & Logic Unit (ALU)
The part of the central processing unit that deals with operations such as addition, subtraction, and multiplication of integers and Boolean operations. It receives control signals from the control unit telling it to carry out these operations. For more, click the title above.

Control Unit (CU)
This controls the movement of instructions in and out of the processor, and also controls the operation of the ALU. It consists of a decoder, control logic circuits, and a clock to ensure everything happens at the correct time. It is also responsible for performing the instruction execution cycle. More on the control unit can be discovered by clicking the title above.

Register Array
This is a small amount of internal memory that is used for the quick storage and retreival of data and instructions. All processors include some common registers used for specific functions, namely the program counter, instruction register, accumulator, memory address register and stack pointer. For more, click the title above.

System Bus
This is comprised of the control bus, data bus and address bus. It is used for connections between the processor, memory and peripherals, and transferal of data between the various parts. Click the title above for more.

Memory
The memory is not an actual part of the CPU itself, and is instead housed elsewhere on the motherboard. However, it is here that the program being executed is stored, and as such is a crucial part of the overall structure involved in program execution.




























The ALU, or the arithmetic and logic unit, is the section of the processor that is involved with executing operations of an arithmetic or logical nature. It works in conjunction with the register array for many of these, in particular, the accumulator and flag registers. The accumulator holds the results of operations, while the flag register contains a number of individual bits that are used to store information about the last operation carried out by the ALU. More on these registers can be found in the register array section.

The control unit is arguably the most complicated part of this model CPU, and is responsible for controlling much of the operation of the rest of the processor. It does this by issuing control signals to the other areas of the processor, instructing them on what should be performed next.

A register is a memory location within the CPU itself, designed to be quickly accessed for purposes of fast data retrieval. Processors normally contain a register array, which houses many such registers. These contain instructions, data and other values that may need to be quickly accessed during the execution of a program.

The system bus is a cable which carries data communication between the major components of the computer, including the microprocessor.

Reference
http://www.eastaughs.fsnet.co.uk/cpu/structure-bus.htm

COMP 372 Assgn. # 3 Different ROM and RAM IC's

ROM - Read-only memory: On ROM, data is prerecorded for read only which can not be removed. ROM is nonvolatile and it retains its contents regardless the computer is on or off.

RAM - Random access memory: whose contents can be accessed (read, write and remove) in any order. This is in contrast to sequential memory devices such as magnetic tapes, discs and drums, in which the mechanical movement of the storage medium forces the computer to access data in a fixed order. RAM is usually used for primary storage in computers to hold active information such as data and programs. Common forms of RAM are: SRAM (Static RAM) and DRAM (Dynamic RAM).

There are also some hybrad memory types which combines characters of both RAM and ROM, such as Flash memory, NVRAM and EEPROM.

Type	Volatile	Writeable	Erase Size	Max Erase Cycles	Speed
SRAM	Yes	Yes	Byte	Unlimited	Fast
DRAM	Yes	Yes	Byte	Unlimited	Moderate
Masked ROM	No	No	n/a	n/a	Fast
PROM	No	Once, with a device programmer	n/a	n/a	Fast
EPROM	No	Yes, with a device programmer	Entire Chip	Limited	Fast
EEPROM	No	Yes	Byte	Limited	Fast to read, slow to erase/write
Flash	No	Yes	Sector	Limited	Fast to read, slow to erase/write
NVRAM	No	Yes	Byte	Unlimited	Fast

Computer Memory: RAM and ROM

Related Terms:RAM, ROM, Flash memory, DRAM, SRAM

References

http://www.networkdictionary.com/hardware/cm.php

http://www.arcadecomponents.com/catalog/item/2251646/1693323.htm#image_1

COMP 372 Assgn. # 2 Different IC numbers & Layout for Decorders,Encorders & Multiplexers

IC Numbers (For Decorders)

SN54246
SN544247
SN54LS247
SN64LS248
SN74246
SN74247
SN74LS24
















Ic Numbers For Encorders

MM54C922-16 Key Encorder
MM74C922-16 Key Encorder
MM54c923-20 Key Encorder
MM74C923-20 Key Encorder















Block Diagram





















Ic Numbers For Multiplexers

CD 4051BC Single 8 Channel Analog Multiplexer
CD4052BC Single 8 Channel Analog Multiplexer
CD4053BC Single 8 Channel Analog Multiplexer































































Reference
http://www.nalanda.nitc.ac.in/industry/appnotes/TI_logic/data/www.ti.com/sc/psheets/sdls083/sdls083.pdf
http://eshop.engineering.uiowa.edu/NI/pdfs/00/60/DS006037.pdf
http://www.ic-on-line.cn/IOL/viewpdf/CD4053_10260.htm

COMP 372 Assgn. # 1 IC Layout for 6800 family

The 68000 has eight 32-bit data registers (D0-D7), eight 32-bit address registers (A0-A7), a 32-bit program counter, two 32-bit stack pointers, and a 16-bit status register (Figure 7-1). The processor is capable of handling data as either 32-bit-long words, 16-bit words, bytes, or bits.

N.B CLICK AN IMAGE FOR AN EXPANDED VIEW

Figure 7-1: Programmer's model of the 68000

The processor has two modes of operation, supervisor mode (operating system) and user mode (applications). The mode of operation is made available to external hardware, thereby allowing the address decoder to have separate supervisor and user spaces.

Figure 7-2: MC68000 block diagram and pinout

Reference
www.datasheetarchive.com/search.php?t=0&q=6800+&manystr=&sub.x=0&sub.y=0