HOMEWORK: pp. 12 - #2, 4, 6, 7
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Computers - problem-solving tool (machine that accepts data, stores data, processes data and presents results). analog vs. digital
How we use computers - use programs (software) for wordprocessing, spreadsheets, data management, communciations, graphics
What computers can do -
(1) data processing,data - raw facts and figures,information - processed data
(2) control - direct robots, traffic systems, intelligent buildings
(3) design & development,engineers & surgeons
(4) data communications
Functions of a computer- arithmetic operations, comparisons, store & retrieve data.
How computers operate - input, process, store/retrieve, output.
What computers cannot do -
cannot identify problem to be solved
design software
interpret and use information to solve problem
COMPUTER SYSTEMS -
hardware:physical devices (input, output, etc.)
software:instructions for hardware
data: raw facts and figures
microcomputers, minicomputers, mainframes, supercomputers
Where computers are used -
business & industry
science & technology
health care
simulation
education & libraries
government & legal systems
recreation and entertainment
CONTEMPORARY MULTILEVEL COMPUTERS
| Level 6 - Application Level |
| Level 5 - Problem-oriented language level |
| Level 4 - Assembly Language level |
| Level 3 - Operating System Machine level |
| Level 2 - Conventional machine level |
| Level 1 - Microprogramming level |
| Level 0 - Digital logic level (digital) |
| Level -1 - Device (Transistor) level (analog) |
The digital logic level contains objects (electrical circuits) called gates which are digital having inputs and outputs of either 0 or 1. Gates are built from a few transistors and are used to represent simple functions like AND, OR or NOT.
Microprograms are a collection of instructions consisting of 0s and 1s which manipulate the gates in level 0. Most computers have a limited number of microprogram instructions which involves moving data from one part of the computer to another or performing simple tests using gates. This is the actual machine level.
Level 2 is a virtual machine level defined by a microprogram. Each machine instruction at this level is interpeted by the microprogram.
ex.Level 3 usually includes many of the Level 2 instructions plus additional instructions, a different memory organization, ability to run two or more programs in parallel and other features. Some level 3 instructions are interpreted by the operating system and some by the microprogram.
Level 4's assembly language is a symbolic form for one of the underlying languages.
ex.
mov ax, 1
mov bx, 2
add ax, bx
Level 5 is the high level languages like C++, Pascal, COBOL, etc.
Level 6 are designed for specific applications.
Computers of the 1940s only had conventional machine level and digital logic level. Computers of the 1950s added the microprogramming level to simplify the electronics Prior to 1960, the programmer or the operator hand-loaded the FORTRAN program, the FORTRAN compiler, and the machine language interpreter.
Top Two Levels of The ACM Computing Classification System
Organization of a simple computer:
HOMEWORK: pp. 12 - #2, 4, 6, 7
BACK TO Computer Science I Page