microsy 1-4.2

Mainframes.

A large and powerful computer used for business data processing in medium to large corporations that require much more computing and storage capacity than workstations can handle.

High-level language

A programming language that uses English-like commands or instruction. It is the easiest to use and contains man complicated or advanced instructions.

keyboard, joystick, mouse, input pen, touch screen, trackball, scanner, bar code readers, microphone, floppy disks, magnetic tapes, compact disks.

examples of input unit

Magnetic Disks (diskette, hard disk), Drums, Tapes, CD-ROMS, DVD-ROMS

examples of secondary storage

conditional and control flags

flags are divided into

third generation language

high-level langugae is ska

Memory Address Register

holds the address location to or from which data are to be transferred

Working Storage Space

holds the data being processed as well the intermediary results of such processes.

Program Storage Area

holds the programs or processed instructions given by the user. It stores the entire program that is being executed.

Execution Unit

responsible for decoding and executing all instructions. It consists of an ALU, status and control flags, eight general-purpose registers, temporary registers, and queue control logic.

Output Unit

sends processed results to the outside world. Examples:

Von Neumann architecture

simply means that programs (together with data) are stored in main memory during execution.

General Purpose Registers

these are used in any manner that the programmer wishes. Each is addressable as a 16-bit register (AX, BX, CX, DX) as two 8-bit registers (AH, AL, BH, BL, CH, CL, DH and DL).

Pointer and Index Registers.

they are more often used to index or point to the memory location holding the operand data for many instructions.

Input Storage Area

this area accepts and stores the input data to be processed

data bus

this is for the transmission of data

address bus

this specifies the location of data in MM

data bus, address bus, control bus

three main groupings of lines

Auxiliary Carry Flag (AF)

-b3 This flag is used exclusively for BCD arithmetic. It is set to 1 if there is a carry out of bit 3 (b3) during an addition or borrow by bit 3 during a subtraction.

Interrupt Enable Flag (IF)

-b9 If set, a certain type of interrupt ( a maskable interrupt) can be recognized by the CPU; otherwise, these interrupts are ignored.

DX (Data)

. This holds the most significant part of the product after a 16-bit multiplication and the most significant part of the dividend before a division.

Bus Interface Unit

. This is responsible for fetching an instruction, the operand of an instruction or data from the MM.

assembly language

A programming language that uses "abbreviations" or mnemonics in place of binary patterns in order to make the task of programming easier. Mnemonics are designed to be easy to remember and are a significant improvement over binary digits.

easy to learn predefined functions portability

Advantages of High-Level Languages

compact code speed flexible

Advantages of Low-level Languages

Programming effort. The time it takes to develop software. The cost of software development.

All 4GLs are designed to reduce:

bottleneck

Since programs must reside in MM during execution, MM is often referred to as the --- in most computer operations.

Workstations

Although still of desktop dimensions, these machines have a computational power which is significantly higher than that of personal computers.

Control UNIT

CU is the nerve center of a computer. It controls the entire activity of the CPU. It controls and coordinates the order and execution of program instructions. It accesses instructions in sequence, interprets them and then directs their implementation

FORTRAN (FORmulaTRANslation) COBOL (COmmonBusiness-Oriented Language) BASIC (Beginner's All-Purpose Symbolic Instruction Code) Pascal

Examples of High-level Languages:

20 GB -8 TB

Hard Disk nowadays has a capacity ranging from

Processing Unit

It contains a number of high speed (10 times faster than MM) storage elements called registersthat are used for temporary storage of frequently used operands. It is mandatory for data to be stored in a register before it can be processed.

random-access memory (RAM)

MM is also known as

Von Neumann Architecture

Most computers follow the ---,

Stored Program Architecture or Fetch-Decode-Execute Architecture.

Most computers follow the Von Neumann Architecture, also known as the

processor array architecture, multiprocessor architecture, dataflow architecture, and neural network architecture.

Not all computers follow the Von Neumann architecture. Some examples are

Central Processing Unit or Central Processor

Processing Unit. Also called the

16 to 64 bits

Typical word lengths range from

Prefetch Queue

The 8086/8088 prefetches the succeeding instructions while executing the current one

Arithmetic-Logic Unit and Control Unit

The CPU is composed of the Arithmetic-Logic Unit (ALU) and the Control Unit (CU).

Machine Language Assembly Language High-level Language 4GL Language

The different types of programming languages are as follows:

words

The information in MM is often processed in groups of fixed size called

machine language

The natural or primitive language that the computer actually understands. This programming language consists of 0's and 1's which makes programming very difficult.

word length

The number of bits in a word is the ---- of the computer.

memory access time

The time required to access one word is the

Supercomputers.

These are used for large-scale numerical calculations found in applications such as weather forecasting and aircraft design and simulation. In mainframes and supercomputers, the main functional units may compromise a number of separate and often large parts.

Status Register or Processor Status Word

This contains 16 bits, but 7 of them are not used. Each bit in the PSW is a flag.

Data Segment.

This contains data referenced by almost all instructions and many addressing modes. Data are almost always moved into or out of MM via the data segment. The physical address of the data is generated by adding the contents of one of the index or pointer registers (BX, CX,DI, SI or MM) to the contents of DS x 10H.

Code Segment.

This contains the program or code. The address of the next instruction executed by the 8086/8088 is generated by adding the contents of IP (offset address) to the contents of CS x 10H.

direction flag

This flag is used by string manipulation instructions. If clear, the string is processed from its beginning with the first element having the lowest address. Otherwise, the string is processed from the high address towards the low address.

CX (Count)

This holds the count for certain instructions such as shift count (CL) for shifts and rotates, the number of bytes (CX) operated upon by the repeated string instructions, and a counter (CX) with the LOOP instruction.

control bus

This indicates the direction of data transfer and coordinates the timing of events during the transfer

Stack Segment.

This is for the LIFO stack. The physical address is a combination of the contents stack pointer (SP,BP) plus SS x 10H

Extra Segment.

This is normally for string instructions. When a string instruction is executed, the destination location is addressed by the destination index register (DI) plus ES x 10H.

DI (Destination Index)

This is normally used to address destination data indirectly for use with the string instructions.

BP (Base Pointer)

This is often used to address an array of data in memory.

AX (Accumulator)

This is often used to hold temporary result after an arithmetic and logic operation.

BX (Base)

This is often used to hold the base address of data located in the memory

Execution Unit

This is responsible for executing the instructions.

Bus Interface Unit

This is responsible for fetching an instruction, the operand of an instruction or data from the MM.

Zero Flag (ZF)

This is set to 1 if the result of the previous operation is zero and 0 if the result is nonzero.

Personal Computers.

This is the most common computer which has found wide use in homes, schools, and business offices.

Instruction Pointer

This is the program counter.

SP (Stack Pointer)

This is used to address data in a LIFO (last-in first-out) stack memory. This occurs most often when the PUSH and POP instructions are executed.

SI (Source Index)

This is used to address source data indirectly for use with string instructions.

Secondary Storage or Auxiliary Storage.

This is used when large amounts of data have to be stored (on a more permanent basis), particularly if some of the data need not be accessed very frequently. This is a storage medium that will hold data and program/sets of instructions even if the computer system is switched off.

Primary Storage or Main Memory (MM).

This is where programs are stored during their execution. The MM is a fast memory capable of operating at electronic speeds

Store or Write.

This transfers a word of information from the CPU to a specific MM location. This destroys the former contents of that location

Fetch or Read.

This transfers the contents of a specific MM location to the CPU. The word in the MM remains unchanged.

distinct address

To provide easy access to any word in MM, a --- is associated with each word location.

Program Counter

contains the memory address of the instruction to be executed. During execution, the contents of the PC are updated to point to the next instruction.

fourth-generation programming language

a programming language designed with a specific purpose in mind such as the development of commercial business software. The process of software development had been much improved with modern block structured third-generation programming languages but it was still frustrating, slow, and error prone to program computers.

Input Unit

accepts coded information from human operators of from other computers

Addresses

are numbers that identify successive locations.

Workstations

are often used in engineering applications, especially for interactive design work (CAD/CAM).

Buffer Registers

are used to hold information during transfers. These prevent a highspeed processor from being locked to a slow I/O device during a sequence of data transfers

Parity Flag (PF) -

b0 -b7 This is set to 1 if the low-order 8 bits of the result of the previous operation contain an even number of 1s. Otherwise, it is reset to

Overflow Flag (OF)

b14 and b15 This is set to 1 if an overflow occurs, i.e., a result is out of range. More specifically, for addition this flag is set to 1 when there is a carry into the MSB and no carry out of the MSB or vice-versa. For subtraction, it is set to 1, when the MSB needs to borrow and there is no borrow from the MSB, or vice-versa.

Carry Flag (CF) -

b15 An addition causes this flag to be set to 1 if there is a carry out of the MSB, and a subtraction causes it to be set to 1 if a borrow is needed.

Sign Flag (SF)

b7 or b15 This is equal to the MSB of the result of the previous operation. 0 if positive, 1 if negative.

input, memory, arithmetic and logic, output, control units.

computer consists of five functionally independent main parts:

Memory Data Register

contains data to be written or read out of the addressed of location

Instruction Register

contains the instruction that is being executed

computer memory

internal storage is called

4004

is a 4-bit ɥpwith maximum memory of only up to 4,096 4-bit memory locations (2,048 bytes).

bus

is a collection of wires that connect several devices within a computer system

digital computer

is a fast electronic calculating machine that accepts digitized input information, processes it according to a list of internally stored instructions, and produces the resulting output information.

RAM

is a memory in which any location can be reached in a short, fixed amount of time.

assembler

is a special program that translates assembly language mnemonics into machine language.

compiler

is a special program that translates high-level language instructions into machine language.

8008

is an 8-bit ɥpcapable of addressing 16,384 bytes and has 48 instructions.

stack

is implemented in MM of the 8086/8088. it is 64KB long and is organized from a software point of view as 32K words.

memory unit

is organized so that the contents of one word, containing n bits, can be stored or retrieved in one basic operation.

physical memory

is the actual organization of the memory that the hardware designers see. The physical memory map of the 8088 is identical to its logical memory map.

Computer Architecture

is the design of computers, including their instruction sets, hardware components, and system organization

Logical memory

is the name given to the memory viewed by the

ALU

is where all arithmetic and logic operations and manipulation of numbers takes place.

computer program

list of instructions is called a

Output Storage Area

maintains the final outputs or processed results of the operations.