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CHAPTER Mainframe/Mini Related Communication Equipment. Chapter Objectives. Present mainframe and minicomputer related communication hardware that has not been presented elsewhere Front-end processors, concentrators, protocol converters etc. - PowerPoint PPT Presentation
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CHAPTER CHAPTER
Mainframe/Mini Mainframe/Mini Related Related
Communication Communication EquipmentEquipment
Chapter Objectives
• Present mainframe and minicomputer related communication hardware that has not been presented elsewhere– Front-end processors, concentrators, protocol
converters etc.
• Describe the different types of terminals such as the ASCII and EBCDIC terminals, smart terminals etc.
• Present examples of the use of the above equipment in practice
Chapter Modules
• Mainframe Data Communication Equipment: Front End Processor and Concentrator
• Minicomputer Data Communication Equipment: Communication Controllers
• Protocol Converters• Data Terminal Equipment
END OF CHAPTER END OF CHAPTER INTRODUCTIONINTRODUCTION
MODULE
Mainframe Communication Equipment: Front End
Processor and Concentrator
Definition of DCE and DTE
• DCE– Data Communication Equipment
• DTE– Data Terminal Equipment
DCE and DTE in the Real World
MainframeComputer
DCE
DCE
DTE
DTE
Front End Processors, Concentrators, Protocol Converters etc.
Printers,Terminal etc.
Some Mainframe Communication
Equipment• Front End Processors
– Manages the network traffic in a mainframe environment
• Multiplexers– Discussed in an earlier chapter in
detail
• Communication controllers– Controllers, concentrators etc.
Mainframe Communication Equipment (Cont.)
• Protocol converters– Used for linking devices that operate
under a different protocol - different from the mainframe protocol
Overview of Communication
Controllers• Used extensively in mainframes
– 3270 controllers for IBM mainframes
• Level of sophistication– On one end of the spectrum is the front end
processor– On the other end is the communication
controller– There are also the other intermediate
communication controllers and devices that are grouped under the 3270 family of communication equipment
Front End Processors (FEPs)
• Computers by themselves• Connected to a mainframe for the
purpose of managing the network traffic• FEPs reduce the load on the CPU
– Enable the CPU to perform its primary task of running applications
• FEP is a comprehensive DCE – Minicomputers, modems, LANs etc. can be
attached to the mainframe through the FEP
A Front End Processor Connection
Mainframe
Front End ProcessorMini-Computer
Term. Term. PCPC
Concentrator
LAN
ModemServer
Ter.
External Lines
Gateway
Ter.
END OF MODULEEND OF MODULE
MODULE
Minicomputer Data Communication Equipment:
The Communication Controller
Communication Controllers for Minicomputers
• In the case of the minicomputer, the controllers can be of the internal or external type
• If they are internal controllers, they are installed in the expansion slot of the minicomputers
• Manages the network traffic among the host, DTE and DCE
Controllers for AS 400
• Known as the 5250 controllers– Fall under the 5250 family of DCE
• Compare this with the mainframe’s 3270 family of DCE
Connecting DTE to a Communication Controller
ASCIIPrinter
ASCIITerminal
HP Plotter
Modem
AS 400
5250CommunicationController
AS/400 Connection to Terminal Equipment
AS/400 withBuilt-in Communication
Controller
AS/400 Terminal Equipment
Source: Black Box
AS/400 LAN Connection
AS 400
Server
PC
PC
Plotter
Modem PoolPrinter
OS/400
OS/2
AS 400 LAN Connection Practical Example
Remote AS 400Central Unit
LAN
Source: Black Box
In Summary
• Two different ways by which a minicomputer can be connected to other devices including the DTE
• Connect the terminal equipment directly to the minicomputer through its communication controller
• Link the mini to its terminal equipment over a LAN
END OF MODULEEND OF MODULE
MODULE
Protocol Converter
Definition and Use
• A protocol converter can be defined as an equipment used for interfacing systems working under different protocols
• Protocol converters are most widely used for connecting peripheral devices to hosts– An example is the connection of ASCII
terminals to IBM mainframes
ASCII and EBCDIC Terminals
• EBCDIC terminals– Standard terminals used with the IBM
mainframe
• Code conversion difference is present between the EBCDIC and ASCII terminals
• A protocol converter is required when an ASCII terminal is to be linked to an IBM mainframe
ASCII Terminal Link to an IBM Mainframe
IBM 3274
Controller
ProtocolConverter
ToIBMMainframe (FEP) ASCII Terminal
PSTN
Modem
Use of Protocol Converter to Connect ASCII Equipment to
IBM Mainframe
Protocol Converter
ASCII Printer PC (ASCII) Terminal
Source: Black Box
Mainframe Modem Connection
To IBM Mainframe
Unix ComputerRemote PC
Source: Black Box
Protocol Converter Used in Mini Computer Connection
AS 400
ASCIIPrinter
ASCIITerminal
HP Plotter
Modem
TwinaxMulti-portProtocolConverter
Protocol Converters:AS/400 to
ASCII Connection
Source: Black Box
Protocol Converter: AS400 to LAN and Printer
Connection
Source: Black Box
Preferred AS 400 Connection to a LAN
AS 400
PC
Network Interface Card LAN
In Summary
• Frequent Usage– Connecting ASCII equipment to
computers that operate under a different protocol
• Utilized for connecting DTE to the mini and mainframe computers
END OF MODULEEND OF MODULE
MODULE
Data Terminal Equipment (DTE)
EBCDIC and ASCII Terminals
• EBCDIC– IBM mainframes
• ES 9000 series
– IBM minis • AS 400 series
• ASCII– Popular in the Unix environment
• IBM RS 6000 Unix computer• DEC computers running the Unix OS
– Most recognizable ASCII terminal is the VT 100 terminal
Initial (Dumb) Terminals
Mainframe DumbTerminals
Only involved in conveying the information betweenthe mainframe and the terminal.
Smart Terminals
• Smart terminals are likely to incorporate reasonably powerful processors within themselves
• They are able to perform local processing such as the local editing of information on the screen
Dumb Terminals
• Do not have processors for local processing
• They rely on the host to perform most operations
• Overloading the CPU is not a desirable course of action
• The use of dumb terminals is on the decline
Microcomputer as a Terminal
• There are two methods by which a microcomputer can be connected to a mainframe to act as a terminal
• One involves a direct connection to a concentrator – Terminal emulation hardware and software are
required for terminal emulation
• The alternative method is to connect a LAN consisting of microcomputers to the mainframe
Micro as a Terminal: Direct Connection
IBM Cluster
Controller.
Micro
To IBMMainframe (FEP)
Terminal EmulationBoard
Terminal EmulationSoftware
IBM Terminal Emulation
Source: Black Box
LAN Based Connection
PC
PC
PCFEP
MainFrame
PC
Gateway or similar device
Terminal Emulation Software
RS 6000: Native ASCII Connection
AIX (Unix) Computer
Terminals
Source: Black Box
In Summary
• Two major types– ASCII and EBCDIC
• Smart and Dumb terminals• Smart terminals engage in local
processing• Microcomputers are increasingly
being used to emulate the terminals
END OF MODULEEND OF MODULE
END OF MODULE END OF MODULE
END OF CHAPTEREND OF CHAPTER