View
221
Download
0
Category
Preview:
Citation preview
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
8/3/2019 Mini,miro and mainframe computer
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
8/3/2019 Mini,miro and mainframe computer
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
8/3/2019 Mini,miro and mainframe computer
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
8/3/2019 Mini,miro and mainframe computer
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
8/3/2019 Mini,miro and mainframe computer
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
8/3/2019 Mini,miro and mainframe computer
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
8/3/2019 Mini,miro and mainframe computer
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
8/3/2019 Mini,miro and mainframe computer
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
8/3/2019 Mini,miro and mainframe computer
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
8/3/2019 Mini,miro and mainframe computer
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).
Recommended