Title: Parallel Connections
1Parallel Connections
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- Michael Fromwiller
- CS 147 Spring 08
- Dr. Sin-Min Lee
2Parallel Interfaces
- Buses transfer data inside computers.
- Monitors, printers, and other devices do not
connect to the system bus. - External devices connect to interface circuits
which are used to manage the connection. - Proper connections require the ability to send
and receive data.
3Centronics Printer Interface
- Multi-wire parallel link.
- Transfers 8 bits of ASCII code simultaneously.
- Typical speed 100 kbytes/sec over10 meters.
- Not considered a bus
- Does not offer support for more than two devices.
4Centronics Printer Interface
- Up to 8x faster than serial connections! but
suffers from skew - Differences in wire resistances
-
- Lots of wires
- Signal degradation, delays, and
- data corruption. Yuck.
Low Skew
High Skew
5Centronics Printer Interface
- Three standards for this interface
Mode Name Speed I/O Controller
SPP Standard Parallel Port 100 kbytes/s Output Software Controlled
EPP Enhanced Parallel Port 1 Mbytes/s Output Input Hardware Controlled
ECP Extended Capability Port 5 Mbytes/s Output Input DMA w/ FIFO
6Standard Parallel Port (SPP)
- Software handles connection (slow)
- Host sends important data (a print job, for
example) to device. - Device sends status messages to the host
- Accepting data
- Busy, try again later
- Out of paper
- Error found
- Typical setup between devices for asynchronous
handshaking.
7EPP and ECP Modes
- Both offer bi-directional lines for data
communication between device and host. - Important for Plug-and-Play process.
- Hardware handles data transmission
- Software writes data to port buffer
- Hardware handles the rest (fast!)
8SCSI - Small Computer Systems Interface
- Fast asynchronous byte-wide bus(5 Mbytes/sec)
connecting up to 8 devices - A secondary bus which relieves the traffic from
the main bus. - Intended for
- Hard disk drives
- CD-ROM drives
- Tape units
9SCSI - Small Computer Systems Interface
- Variations of SCSI standards
- Fast SCSI
- (10 Mbytes/sec synchronous transfer mode)
- Wide SCSI
- (40 Mbytes/sec with 32 bit data bus)
- Useful for
- Multiple computers with shared drives
- Multiple CD-ROM burners for mass production
- Tape drives
10IDE Intelligent Drive Electronics
- Simplified version of the ISA bus.
- Standard was quickly accepted.
- Used by cheapest hard disk drives
- Used by most common hard disk drives
- Ribbon connections support two devices
- Master
- Slave.
- Plugs directly into the AT bus.
11AT / ISA bus
- Appeared around the time the Intel 8088 processor
came out. - Ran at 4.77 Mhz
- Later topped off at 8.33 Mhz
- Faster processors would wait till the ISA bus was
finished, affecting speed. - Pentium CPUs made the speed difference clear.
- Extended ISA (EISA) clocked at 33 Mhz, but was
overshadowed by the new PCI bus.
12PCI Peripheral Component Interconnection
- PCI bus isolated from main bus by a bridge
device, such as the i82443. - North Bridge
- Handles PCI components
- South Bridge
- PCI to ISA bridging device, such as the i82371
- Development of the mini-PCI was brought about by
laptop computers, for PC add-ons.
13PCI Peripheral Component Interconnection
- PCI bus operates in two modes
- Multiplexed Mode
- A single 32 bit bus that is shared by address and
data information. - Increased bus width, but reduced data rate.
- Burst Mode
- Same idea as EDO DRAM. After one address has been
sent, several data items follow in quick
succession. - Bridge is capable of assembling these packets
of data and bursting it to the PCI bus when ready.
14Plug-and-Play
- Introduced by Microsoft.
- Main purposes
- Allow computer to auto-configure hardware.
- Simplify hardware installation.
- Make the PC more user friendly
- Released with Windows 95.
- Fully supported by Windows 2000/XP.
15PCMCIA Personal Computer Memory Card
International Association
- Credit card sized
- Originally intended for memory expansion for
laptops. - Designed for hot swapping. No need to turn off
or reboot laptops. Just pop and go! - Manufacturers took it a lot further
- Modems and Ethernet interfaces
- Video cards
- Parallel ports
- Disk drives
- Pretty much anything!
16Sources
- All information from this presentation can be
found inComputer Systems Architecture A
Networking ApproachRob Williams. Chapter 11 - Low and high skew images
- http//www.spectra-strip.amphenol.com
- Parallel printer cable image
- http//www.nuggetlab.com/comptia_files/equipment/
cable_Parallel20Cable20showing2025-pin20end.jp
g - SCSI ribbon cable image
- http//www.qvs.com/prodimages/SCU160-4T_LR.jpg
- IDE ribbon cable image
- http//www.cable-house.com/images/cables/internal
20cables/ide_ata133_ribbon_cable.jpg - Granny with computer image
- http//www.boston.com/business/blog/filter/momtech
support.jpg - PCMCIA card image
- http//upload.wikimedia.org/wikipedia/commons/b/b1
/Pcmcia-type-ii-and-iii.jpg