Mini,miro and mainframe computer

8/3/2019 Mini,miro and mainframe computer

1/11

What is main frame computer?

Mainframes (often colloquially referred to as "big iron") are powerful computers used primarily by

corporate and governmental organizations for critical applications, bulk data processing such as census,

industry and consumer statistics, enterprise resource planning, and financial transaction processing.

The term originally referred to the large cabinets that housed the central processing unit and main

memory of early computers. Later the term was used to distinguish high-end commercial machines from

less powerful units.

Most large-scale computer system architectures were firmly established in the 1960s and most large

computers were based on architecture established during that era up until the advent of Web servers in

the 1990s.

Description:

ost modern mainframe design is not so much defined by single task computational speed,

typically defined as MIPS rate or FLOPS in the case of floating point calculations, as much as

by their redundant internal engineering and resulting high reliability and security, extensive

input-output facilities, strict backward compatibility with older software, and high hardware and

computational utilization rates to support massive throughput. These machines often run for years

without interruption, with repairs and hardware upgrades taking place during normal operation.

oftware upgrades require resetting portions of the system, and are only non-disruptive when

using facilities such as IBM's z/OS and Parallel Sysplex, or Unisys' XPCL, which support workload

sharing so that one system can take over another's application while it is being refreshed. In more

current development and implementation of mainframe infrastructure, there have been several

mainframe installations that have delivered over a decade of service as of 2007, without interruption.

Mainframes are defined by high availability, one of the main reasons for their longevity, since they are

typically used in applications where downtime would be costly or catastrophic. The term reliability,

availability and serviceability (RAS) is a defining characteristic of mainframe computers. Proper planning

and implementation is required to exploit these features, and if improperly implemented, may serve to

inhibit the benefits provided. In addition, mainframes are more secure than other computer types.

M

S


2/11

n the 1960s, most mainframes had no explicitly

interactive interface. They accepted sets of punched

cards, paper tape, and/or magnetic tape and operated

solely in batch mode to support back office functions,

such as customer billing. Teletype devices were also

common, for system operators, in implementing

programming techniques. By the early 1970s, many

mainframes acquired interactive user interfaces and

operated as timesharing computers, supporting hundreds

of users simultaneously along with batch processing.

Users gained access through specialized terminals or, later, from personal computers equipped with

terminal emulation software. Many mainframes supported graphical terminals, and terminal emulation,

but not graphical user interfaces, by the 1980s. This format of end-user computing reached mainstream

obsolescence in the 1990s due to the personal computer.

istorically, mainframes acquired their name in part because of their substantial size, andbecause of requirements for specialized heating, ventilation, and air conditioning (HVAC), and

electrical power, essentially posing a "main framework" of dedicated infrastructure. The

requirements of high-infrastructure design were drastically reduced during the mid-1990s with CMOS

mainframe designs replacing the older bipolar technology. IBM claimed that its newer mainframes can

reduce data center energy costs for power and cooling, and that they could reduce physical space

requirements compared to server farms.

Characteristics:

early all mainframes have the ability to run (or host) multiple operating systems, and therebyoperate as a host of a collective of virtual machines. In this role, a single mainframe can replace

higher-functioning hardware services available to conventional servers. While mainframes

pioneered this capability, virtualization is now available on most families of computer systems, though

not always to the same degree or level of sophistication.

ainframes can add or hot swap system capacity without disrupting system function, with

specificity and granularity to a level of sophistication not usually available with most server

solutions. Modern mainframes, notably the IBM series, System z9 and System z10 servers,

offer two levels of virtualization: logical partitions (LPARs, via the PR/SM facility) and virtual machines

(via the z/VM operating system). Many mainframe customers run two machines: One in their primary

data center and one in their backup data centerfully active, partially active, or on standbyin case

there is a catastrophe affecting the first building. Test, development, training, and production workload

for applications and databases can run on a single machine, except for extremely large demands where

the capacity of one machine might be limiting. Such a two-mainframe installation can support

continuous business service, avoiding both planned and unplanned outages. In practice many customers

I

H

N

M


3/11

use multiple mainframes linked either by Parallel Sysplex and shared DASD (in IBM's case)[citation

needed], or with shared, geographically dispersed storage provided by EMC or Hitachi.

ainframes are designed to handle very high volume input and output (I/O) and emphasize

throughput computing. Since the mid-1960s, mainframe designs have included several

subsidiary computers (called channels or peripheral processors) which manage the I/Odevices, leaving the CPU free to deal only with high-speed memory. It is common in mainframe shops to

deal with massive databases and files. Gigabyte to terabyte-size record files is not unusual. Compared to

a typical PC, mainframes commonly have hundreds to thousands of times as much data storage online,

and can access it much faster. Other server families also offload I/O processing and emphasize

throughput computing.

ainframe return on investment (ROI), like any other computing platform, is dependent on its

ability to scale, support mixed workloads, reduce labor costs, deliver uninterrupted service

for critical business applications, and several other risk-adjusted cost factors.

ainframes also have execution integrity characteristics for fault tolerant computing. For

example, z900, z990, System z9, and System z10 servers effectively execute result-oriented

instructions twice, compare results, arbitrate between any differences (through instruction

retry and failure isolation), then shift workloads "in flight" to functioning processors, including spares,

without any impact to operating systems, applications, or users. This hardware-level feature, also found

in HP's nonstop systems, is known as lock-stepping, because both processors take their "steps" (i.e.

instructions) together. Not all applications absolutely need the assured integrity that these systems

provide, but many do, such as financial transaction processing.

M

MM


4/11

What is mini-computer?

A minicomputer (colloquially, mini) is a class of multi-user computers that lies in the middle range of the

computing spectrum, in between the largest multi-user systems (mainframe computers) and the

smallest single-user systems (microcomputers or personal computers).

History:

1960s: Origin; 1970s: Market entrenchment

he term evolved in the 1960s to describe the "small" third generation computers that

became possible with the use of integrated circuit and core memory technologies. They

usually took up one or a few cabinets the size of a large refrigerator or two, compared

with mainframes that would usually fill a room. zzThe first successful minicomputer was Digital

Equipment Corporations 12-bit PDP-8, which cost from US$16,000 upwards when launched in

1964. The important precursors of the PDP-8 include the PDP-5, LINC, the TX-0, the TX-2, and

the PDP-1. Digital Equipment gave rise to a number of minicomputer companies along

Massachusetts Route 128, including Data General, Wang Laboratories, Apollo Computer, and

Prime Computer.

T


5/11

ini computers were also known as

midrange computers. They had

relatively high processing power and

capacity that mostly fit the needs of mid range

organizations. They were used in manufacturingprocesses or handling email that was sent and

received by a company. In the 70's they were the

hardware that was used to launch the computer

aided design, CAD, industry and other similar

industries where a smaller dedicated system was needed.

The 7400 series of TTL integrated circuits started appearing in minicomputers in the late 1960s.

The 74181 arithmetic logic unit (ALU) was commonly used in the CPU data paths. Each 74181

had a bus width of four bits, hence the popularity of bit-slice architecture. The 7400 series

offered data-selectors, multiplexers, three-state buffers, memories, etc. in dual in-line packages

with one-tenth inch spacing, making major system components and architecture evident to the

naked eye. Starting in the 1980s, many minicomputers used VLSI circuits.

s microcomputers developed in the 1970s and 80s, minicomputers filled the mid-range

area between low powered microcomputers and high capacity mainframes. At the time

microcomputers were single-user, relatively simple machines running simple program-

launcher operating systems like CP/M or MS-DOS, while minis were much more powerful

systems that ran full multi-user, multitasking operating systems like VMS and Unix, often with

timesharing versions of BASIC for application development (MAI Basic Four systems being verypopular in that regard). The classical mini was a 16-bit computer, while the emerging higher

performance 32-bit minis were often referred to as superminis. At the launch of the MITS Altair

8800 in 1975, Radio Electronics magazine referred to the system as a "minicomputer", although

it would properly be called a microcomputer; as it was the first commercially available personal

computer based on the single-chip microprocessor from Intel.

.

M

A


6/11

The minicomputer's industrial impact and heritage:

everal pioneering computer companies first built minicomputers, such as DEC, Data

General, and Hewlett-Packard (HP) (who now refers to its HP3000 minicomputers as

servers rather than minicomputers). And although todays PCs and servers are clearly

microcomputers physically, architecturally their CPUs and operating systems have evolved

largely by integrating features from minicomputers. In the software context, the relatively

simple OSs for early microcomputers were usually inspired by minicomputer OSs (such as

CP/M's similarity to Digital's RSTS) and multiuser OSs of today are often either inspired by or

directly descended from minicomputer OSs (UNIX was originally a minicomputer OS, while

Windows NTthe foundation for all current versions of Microsoft Windowsborrowed design

ideas liberally from VMS and UNIX). Many of the first generation

of PC programmers were educated on minicomputer systems.

S


7/11

What is micro-computer?

A microcomputer is a computer with a microprocessor as its central processing unit. They are physically

small compared to mainframe and minicomputers. Many microcomputers (when equipped with a

keyboard and screen for input and output) are also personal computers (in the generic sense)

Origin

he term "Microcomputer" came into

popular use after the introduction of

the minicomputer, although Isaac

Asimov used the term microcomputer in his

short story "The Dying Night" as early as1956 (published in The Magazine of Fantasy

and Science Fiction in July that year). Most

notably, the microcomputer replaced the

many separate components that made up

the minicomputer's CPU with one

integrated microprocessor chip. The earliest

models such as the Altair 8800 were often

sold as kits to be assembled by the user,

and came with as little as 256 bytes of RAM,

and no input/output devices other than

indicator lights and switches, useful as aproof of concept to demonstrate what such

a simple device could do. The term

"Microcomputer" also was seriously

employed for the first time designating the Micral N as the first solid state machine designed

with a microprocessor. However, as microprocessors and semiconductor memory became less

expensive, microcomputers in turn grew cheaper and easier to use:

Increasingly inexpensive logic chips such as the 7400 series allowed cheap dedicatedcircuitry for improved user interfaces such as keyboard input, instead of simply a row of

switches to toggle bits one at a time.

Use of audio cassettes for inexpensive data storage replaced manual re-entry of aprogram every time the device was powered on.

Large cheap arrays of silicon logic gates in the form of Read-only memory and EPROMsallowed utility programs and self-booting kernels to be stored within microcomputers.

These stored programs could automatically load further more complex software from

T


8/11

external storage devices without user intervention, to form an inexpensive turnkey

system that does not require a computer expert to understand or to use the device.

Random access memory became cheap enough to afford dedicating approximately 1-2kilobytes of memory to a video display controller frame buffer, for a 40x25 or 80x25 text

display or blocky color graphics on a common household television. This replaced theslow, complex, and expensive teletypewriter that was previously common as an

interface to minicomputers and mainframes.

ll these improvements in cost and usability resulted in an explosion in their popularity

during the late 1970s and early 1980s. A large number of computer makers packaged

microcomputers for use in small business applications. By 1979, many companies such

as Cromemco, Processor Technology, IMSAI, Northstar, Southwest Technical Products

Corporation, Ohio Scientific, Altos, Morrow Designs and others produced systems designed

either for a resourceful end user or consulting firm to deliver business systems such as

accounting, database management, and word processing to small businesses. This allowed

businesses unable to afford leasing of a minicomputer or time-sharing service the opportunity

to automate business functions, without (usually) hiring a full-time staff to operate the

computers.

representative system of this era would have used an S100 bus, an 8-bit processor such

as a Intel 8080 or Zilog Z80, and either CP/M or MP/M operating system. The increasing

availability and power of desktop computers for personal use attracted the attention of

more software developers. In time, and as the industry matured, the market for personal

computers standardized around IBM PC compatibles running DOS, and later Windows. Modern

desktop computers, video game consoles, laptops, tablet PCs, and many types of handhelddevices, including mobile phones, pocket calculators, and industrial embedded systems, may all

be considered examples of microcomputers according to the definition given above.

Colloquial use of the term:

veryday use of the expression "microcomputer" (and in particular the "micro"

abbreviation) has declined significantly from the mid-1980s onwards, and is no longer

commonplace. It is most commonly associated with the first wave of all-in-one 8-bit

home computers and small business microcomputers (such as the Apple II, Commodore 64, BBC

Micro, and TRS 80). Although, or perhaps because, an increasingly diverse range of modern

microprocessor-based devices fit the definition of "microcomputer," they are no longerreferred to as such in everyday speech.

n common usage, "microcomputer" has been largely supplanted by the description

"personal computer" or "PC," which describes that it has been designed to be used by one

person at a time. IBM first promoted the term "personal computer" to differentiate

themselves from other microcomputers, often called "home computers", and also IBM's own

mainframes and minicomputers. Unfortunately for IBM, the microcomputer itself was widely

A

A

E

I


9/11

imitated, as well as the term. The component parts were commonly available to producers and

the BIOS were reverse engineered through clean room design techniques. IBM PC compatible

"clones" became commonplace, and the terms "personal computer," and especially "PC" stuck

with the general public. Since the advent of microcontrollers (monolithic integrated circuits

containing RAM, ROM and CPU all onboard), the term "micro" is more commonly used to refer

to that meaning.

Description

onitors, keyboards and other devices for input and output may be integrated or

separate. Computer memory in the form of RAM, and at least one other less volatile,

memory storage device are usually combined with the CPU on a system bus in one

unit. Other devices that make up a complete microcomputer system include batteries, a power

supply unit, a keyboard and various input/output devices used to convey information to and

from a human operator (printers, monitors, human interface devices). Microcomputers are

designed to serve only one user at a time, although they can often be modified with software or

hardware to concurrently serve more than one user. Microcomputers fit well on or under desksor tables, so that they are within easy access of users. Bigger computers like minicomputers,

mainframes, and supercomputers take up large cabinets or even dedicated rooms.

microcomputer comes equipped with at least one type of data storage, usually RAM.

Although some microcomputers (particularly early 8-bit home micros) perform tasks

using RAM alone, some form of secondary storage is normally desirable. In the early

days of home micros, this was often a data cassette deck (in many cases as an external unit).

Later, secondary storage (particularly in the form of floppy disk and hard disk drives) were built

into the microcomputer case.

More About Mico-Computer

lthough they contained no microprocessors but were built around transistor-transistor

logic (TTL), Hewlett-Packard calculators as far back as 1968 had various levels of

programmability such that they could be called microcomputers. The HP 9100B (1968)

had rudimentary conditional (if) statements, statement line numbers, jump statements (go to),

registers that could be used as variables, and primitive subroutines. The programming language

resembled Assembly language in many ways. Later models incrementally added more features,

including the BASIC programming language (HP 9830A in 1971). Some models had tape storage

and small printers. However, displays were limited to one line at a time. The HP 9100A was

referred to as a personal computer in an advertisement in a 1968 Science magazine[5] but thatadvertisement was quickly dropped. It is suspected that HP was reluctant to call them

"computers" because it would complicate government procurement and export procedures.

he Datapoint 2200, made by CTC in 1970, is perhaps the best candidate for the title of

"first microcomputer". While it contains no microprocessor, it used the 4004

programming instruction set and its custom TTL was the basis for the Intel 8008, and for

practical purposes the system behaves approximately as if it contains an 8008. This is because

M

A

A

T


10/11

Intel was the contractor in charge of developing the Datapoint's CPU but ultimately CTC

rejected the 8008 design because it needed 20 support chips.

nother early system, the Kenbak-1, was released in 1971. Like the Datapoint 2200, it

used discrete transistortransistor logic instead of a microprocessor, but functioned like

a microcomputer in most ways. It was marketed as an educational and hobbyist tool, butwas not a commercial success; production ceased shortly after introduction.

n 1972, for the first time is marketed a solid state computer designed with a microprocessor

(the Intel 8008 8-bit microprocessor). This machine the Micral-N, was created by a

Frenchman Franois Gernelle of the company R2E. In 1973 this machine is widely named in

the entire world a "microcomputer". Since this machine, all computers designed with a

microprocessor, personal computers, workstations even servers, will be called microcomputers.

n 1972, a Sacramento State University team led by Bill Pentz built the Sac State 8008

computer, able to handle thousands of patients' medical records. The Sac State 8008 was

designed with the Intel 8008. It had a full set of hardware and software components: a diskoperating system included in a series of programmable read-only memory chips (PROMs); 8

Kilobytes of RAM; IBM's Basic Assembly Language (BAL); a hard drive; a color display; a printer

output; a 150 bit/s serial interface for connecting to a mainframe; and even the world's first

microcomputer front panel.

irtually all early microcomputers were essentially boxes with lights and switches; one

had to read and understand binary numbers and machine language to program and use

them (the Datapoint 2200 was a striking exception, bearing a modern design based on a

monitor, keyboard, and tape and disk drives). Of the early "box of switches"-type

microcomputers, the MITS Altair 8800 (1975) was arguably the most famous. Most of these

simple, early microcomputers were sold as electronic kits--bags full of loose components whichthe buyer had to solder together before the system could be used.

he period from about 1971 to 1976 is sometimes called the first generation of

microcomputers. These machines were for engineering development and hobbyist

personal use. In 1975, the Processor Technology SOL-20 was designed, which consisted of

one board which included all the parts of the computer system. The SOL-20 had built-in EPROM

software which eliminated the need for rows of switches and lights. The MITS Altair just

mentioned played an instrumental role in sparking significant hobbyist interest, which itself

eventually led to the founding and success of many well-known personal computer hardware

and software companies, such as Microsoft and Apple Computer. Although the Altair itself was

only a mild commercial success, it helped spark a huge industry.

y 1977, the introduction of the second generation, known as home computers, made

microcomputers considerably easier to use than their predecessors because their

predecessors' operation often demanded thorough familiarity with practical electronics.

The ability to connect to a monitor (screen) or TV set allowed visual manipulation of text and

numbers. The BASIC language, which was easier to learn and use than raw machine language,

became a standard feature. These features were already common in minicomputers, with

AI

IV

T

B


11/11

which many hobbyists and early produces were familiar. In 1979, the launch of the VisiCalc

spreadsheet (initially for the Apple II) first turned the microcomputer from a hobby for

computer enthusiasts into a business tool. After the 1981 release by IBM of its IBM PC, the term

personal computer became generally used for microcomputers compatible with the IBM PC

architecture (PC compatible).

Documents

Mini,miro and mainframe computer