Computer Bus and BackPlane Design



[Data Bus Specifications]

The table provides a list comparing the different types of data buses. Both serial and parallel buses are detailed. Color-coding of the table groups buses with similar structures or function.





The first column gives the "common" name of the bus.

Depending on the bus type, either data rate or throughput is given in the second column.
Clocked buses are shown with the clock rate [as data rate], while buses that allow hand shaking are listed with through-put, bits/bytes per second as the data rate ['b'= bits, 'B'= Bytes].
Many of the serial buses are listed by Baud-rate.
The data rate numbers will normally be best case; requiring shortest cable distance, no wait states, optimal communication between devices and so on.

The next column called 'Type' is really the width of the bus in bits. Fiber, Balanced, Unbalanced, and Differential are all types of serial buses.
However all the new "serial" buses may grow in width by providing [sending/receiving] multiple serial paths.

A short description of the bus is provided, followed by the bus topology column. Than the nominal bus voltage level is listed

The two columns to the far right indicate the physical nature of the bus; back plane, cable, fiber...
The acronyms UTP [Un-shielded Twisted Pair], and STP [Shielded Twisted Pair] are indicated for some of the serial buses. Some of the parallel buses just use this column for more detail.
You can either go to a particular bus page by using the Bus Specifications link, or by following the link provided for each bus type below.
A link is not always given for each bus version, only because they would all point to the same page.





Cable and Back Plane Bus Standards
Bus
Data Rate
Type
Description
Topology
Voltage
Coax
Twisted Pair
RS-170
Video
Unbalanced
Video, 75W
Point-to-Point
~ 1V
75W
-------
RS-232
19.2 Kbps
Unbalanced
20 meters, Single Ended
Point-to-Point
~ 5V
15 or 25 pin cable
RS-422
100 Kbps
Balanced
1200 meters, Differential, 100W
Multi-Receivers
+/-7V
------
See RS449 / 530
RS-423
100 Kbps
Hybrid
200 meters, Unbal Tx Bal Rx
Multi-Receivers
+3.6V
------
See RS449 / 530
RS-485
100 Kbps
Balanced
1200 meters, Differential
Multi-Point
+5V
------
STP or UTP
RS-562
64 Kbps
Unbalanced
Mates to RS-232 (low voltage)
Point-to-Point
+/- 3.7v
TBD
EIA-568
100MHz
Balanced
90 meters
Multi-Point
------
------
UTP CAT5
RS-612
52 Mbps
Balanced
Unidirectional
Point-to-Point
ECL
Shielded cable 25 Twisted pair
EIA-644
655 Mbps
Balanced
10 meters, LVDS Elec. Spec only
All types
0.0~2.4V
Back Plane or Cable
RS-694
512 kbps
Unbalanced
Mates with RS-232
Point-to-Point
RS232
------
------
MIL-STD-1553
1.0 Mbps
Balanced
Redundant, half-duplex
Multi-Point
0 to 20V
75 Ohm Twinax
CAN bus
1 Mbps
Balanced
High Noise Environment
Multi-Point
+16V max
------
STP or UTP
AccessBus
100 Kbps
Unbalanced
Similar to I2C, 10 meter
Multi-Point
~ 5V
4 wire,Data/Clk/V/GND
I2C Bus
3.4 Mbps
Unbalanced
2 Wire, 1 Data, 1 Clk-Access Bus
Multi-Point
~ TTL
PWB
SMBus
100 KHz
Unbalanced
2 Wire, based on I2C/Access Bus
Multi-Point
TTL
Undefined
10Base2
10 Mbps
Unbalanced
183 meters, IEEE-802 Thin Net
Multi-Point
ECL
50W
------
10Base5
10 Mbps
Unbalanced
500 meters, IEEE-802 ThickNet
Multi-Point
ECL
50W
------
10Base-T
10 Mbps
Balanced
100 meters, Category 3 cable
Multi-Point
ECL
------
STP or UTP
10Base-F
10 Mbps
Fiber
2000 meters
Point-to-Point
---
Fiber
100Base-T
100 Mbps
Balanced
100 meters, Category 5 cable
Multi-Point
+/- 1.0v
------
STP or UTP
100Base-F
100 Mbps
Fiber
2000 meters
Point-to-Point
---
Fiber
Gigabit Ethernet
1000 Mbps
Fiber or 1000Base-T
Uses Fibre Channel or EIA568 CAT5
Point-to-Point
+/- 1.0v
Fiber or EIA568 STP
ATM
155 Mbps
N/A
Not the Physical Layer
Point-to-Point
N/A
Fiber or STP
SONET
9953.28Mbps
Fiber
STS-3 is 155.52Mbps
Point-to-Point
Optical
Fiber
Fibre Channel
1 Gbps
Differential
SCSI like, Fiber, Coax, or TP
Point-to-Point
ECL
Yes
Yes
FDDI
100 Mbps
Fiber
CDDI uses copper
Token Ring
ECL/PECL
Fiber or Copper
HIPPI
100 Mbps
Fiber
Fiber or Copper
Point-to-Point
Diff ECL
Fiber or Copper
HSSI
52 Mbps
Balanced
SCSI II like
Point-to-Point
Diff ECL
------
STP
RapidIO
10 Gbps
Balanced
Differential LVDS
Star / Mesh
LVDS
Back Plane or Cable
InfiniBand
2.5 Gbps
Balanced
Differential LVDS Pairs
Point-to-Point
LVDS
Copper or Fiber
HyperTransport
800Mbps/bit pair
Balanced
2/4/8/16/32 bits
Daisy-Chained
LVDS
PWB
FireWire, 1394a
400 Mbps
Differential
USB like, Back Plane or cable
Point-to-Point
0.6~0.8V
2 pairs of STP & 2 Power
FireWire, 1394b
800 Mbps
Differential
"...." 1394b
Point-to-Point
0.6~0.8V
2 pairs of STP & 2 Power
USB
12 Mbps
Differential
USB 1.1
Star Topology
0.3~3.6V
------
STP
USB
480 Mbps
Differential
USB 2.0
Star Topology
0.3~3.6V
------
STP
IEEE-488
1 Mbps
8 Bits
Equipment Control
Chained
TTL
24 Pin cable
HS-488
8 Mbps
8 Bits
Equipment Control, ignores NDAC
Chained
TTL
24 Pin cable
ATA-1
8.3Mbps
8 Bits
IDE; Hard / Floppy / CD Drive
Chained
Obsolete
40 pin ribbon cable
ATA-2
16 Mbps
8 Bits
IDE; Hard / Floppy / CD Drive
Chained
Obsolete
40 pin ribbon cable
ATA-3
16 Mbps
16 Bits
EIDE; Hard / Floppy / CD Drive
Chained
TTL
40 pin ribbon cable
ATA-4
33 Mbps
16 Bits
"......." Ultra ATA/33,Added CRC
Chained
TTL
80 pin ribbon/40 connect
ATA-5
66 Mbps
16 Bits
"......." Ultra ATA/66,Added CRC
Chained
TTL
80 pin ribbon/40 connect
ATA-6
100 Mbps
16 Bits
"......." Ultra ATA/100,Added CRC
Chained
TTL
80 pin ribbon/40 connect
ATA-7
133 Mbps
16 Bits
"......." Ultra ATA/133,Added CRC
Chained
TTL
80 pin ribbon/40 connect
Serial ATA
150MBps
Differential
2 differential pairs [Tx/Rx]
Point-to-Point
LVDS
4 conductor cable
SCSI-1
5 MBps
8 Bits
Peripheral Control, 7 devices
Chained
Obsolete
50 pin connector
SCSI-2
40 MBps
8 / 16 /32 Bit
Peripheral Control, 11 devices
Chained
TTL
50 or 68 pin connector
SCSI-3
40 MBps
8 / 16 Bit
Peripheral Control, 16 devices
Chained
TTL
50 or 68 pin connector
Ultra 160 SCSI
160 MBps
32 Bit
Peripheral Control, 4 devices
Chained
TBD
TBD
Ultra 320 SCSI
320 MBps
32 Bit
Peripheral Control, 4 devices
Chained
TBD
TBD
Ultra 640 SCSI
640 MBps
32 Bit
Peripheral Control, 4 devices
Chained
TBD
TBD
PC-XT
4.7MHz
8 Bits
Personal Computer Bus
Card edge
TTL
Obsolete
PC-AT (ISA)
8MHz
16 Bits
Personal Computer Bus
Card edge
TTL
Still used on PC104
EISA
8MHz
32 Bit
PC local bus
Card edge
TTL
Obsolete
Micro Channel
10MHz
32 Bits
Personal Computer Bus
Card edge
TTL
Obsolete
VESA (VLB)
33MHz
32/64 Bit
PC local bus
Card edge
TTL
Obsolete
PISA
Combo
Combo
ISA-PCI Combo @ISA Format
Card edge
TTL
Industrial Computers
PCI
33/66MHz
32/64 Bits
Chip-to-Chip, Multidrop PC Local Bus
Card edge
TTL
Computers
PCI-X
533MHz
32/64 Bits
Chip-to-Chip, Multidrop 4.3GBps
Card edge
CMOS
Computers
PC Card
8MHz
16 Bit
ISA in a PCMCIA form factor
Connector-ized
TTL
Computers
CardBus
33MHz
32 Bit
PCI in a PCMCIA form factor
Connector-ized
PCI
Computers
AGP
66MHz
8/16/32 Bit
PC local bus similar to PCI
Point-to-Point
TTL
Accelerated Graphic Port
AGP 2x
133MHz
8/16/32 Bit
"....." 533MB/s
Point-to-Point
TTL
Accelerated Graphic Port
AGP 4x
266MHz
8/16/32 Bit
"....." 1066MB/s
Point-to-Point
TTL
Accelerated Graphic Port
AGP 8x
533MHz
8/16/32 Bit
"....." 2.1GB/s
Point-to-Point
TTL
Accelerated Graphic Port
PCI Express
2.5Gb/ps
up to 32 Bits
Serial PCI, differential pairs
Point-to-Point
TBD
TBD
AMR/CNR
TBD
TBD
Audio/Modem-Communication Network Riser
TBD
TBD
Card Edge
PC104
8MHz
8/16 Bit
ISA-AT Stacked PC Cards
Back Plane
TTL
Embedded Computers
PC104-Plus
8MHz and 33MHz
8/16/32 Bit
PCI - PC104 Combo
Back Plane
TTL
Embedded Computers
Compact-PCI
266/512Mbps
32/64 Bit
33MHz/66MHz, VME format
Back Plane
CMOS
110 pin 2mm connector
PXI
33MHz
32/64 Bit
cPCI for Instrumentation 3U/6U
Back Plane
TTL
Industrial Computers
AdvancedTCA
TBD
TBD
8U card size
Back Plane
TBD
TBD
VME
40 Mbps
8/16/32 Bit
Euro card format 3U/6U x160mm
Back Plane
TTL
96 pin P1/P2
VME64
80 Mbps
8/16/32/64 Bit
3U/6U x160mm, 6U/9U x320mm,
Back Plane
TTL
190 pin P1/P2, 92 pin P0
VME64x
160 Mbps
8/16/32/64 Bit
2eVME; 3U/6U/9U x160mm (x320mm)
Back Plane
TTL/ETL
190 pin P1/P2, 92 pin P0
VME320
320 Mbps
8/16/32/64 Bit
2eSST; 3U/6U/9U
Back Plane
ABTL
Copy Right-ed
VXI
80 Mbps
64 Bit
VME for Instrumentation 3U/6U/9U
Back Plane
TTL
96 pin P1/P2
Mezzanine
33/64MHz
8/16/32 Bit
PMC and PC MIP cards
Daughter card
PCI
Daughter Bus
P2CI
33MHz
64 Bit
VME P2 bus with PCI
Back Plane
TTL
VME64x P2 Connector
RaceWay
40MHz
32 Bit
VME P2 Crossbar 480Mbps
P2 rear rows A/C
TTL
P2 Daughter card
SkyChannel
320Mbps
32 Bit
VME P2 Crossbar add-on
P2 rear rows
TTL
P2 Daughter card
FPDP
160Mbps
32 Bit
VME (Front Panel Data Port)
Point-to-Point
PECL
Front Panel Connector
AutoBahn
200Mbps
Differential
VME P1
Point-to-Point
PECL
Serial Bus
Futurebus /+
100/3200 Mbps
100/256 Bit
300mm x 300mm card
Back Plane
BTL
2mm Connectors
Std32 Bus
32 Mbps
8/16/32 Bit
Industrial Bus
Back Plane
TTL
Industrial Computers
MultiBus II
80 Mbps
32 Bit
3U/6U x 220mm
Back Plane
TTL
DIN 41612





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Modified 1/26/12
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