Pin
|
Name
|
Description |
Z1
|
GND
|
Ground
|
Z2
|
GND
|
Ground
|
Z3
|
GND
|
Ground
|
Z4
|
GND
|
Ground
|
Z5
|
GND
|
Ground
|
Z6
|
GND
|
Ground
|
Z7
|
GND
|
Ground
|
Z8
|
GND
|
Ground
|
Z9
|
GND
|
Ground
|
Z10
|
GND
|
Ground
|
Z11
|
GND
|
Ground
|
Z12
|
KEY
|
Keyed (no pin)
|
Z13
|
KEY
|
Keyed (no pin)
|
Z14
|
KEY
|
Keyed (no pin)
|
Z15
|
GND
|
Ground
|
Z16
|
GND
|
Ground
|
Z17
|
GND
|
Ground
|
Z18
|
GND
|
Ground
|
Z19
|
GND
|
Ground
|
Z20
|
GND
|
Ground
|
Z21
|
GND
|
Ground
|
Z22
|
GND
|
Ground
|
Z23
|
GND
|
Ground
|
Z24
|
GND
|
Ground
|
Z25
|
GND
|
Ground
|
Z26
|
GND
|
Ground
|
Z27
|
GND
|
Ground
|
Z28
|
GND
|
Ground
|
Z29
|
GND
|
Ground
|
Z30
|
GND
|
Ground
|
Z31
|
GND
|
Ground
|
Z32
|
GND
|
Ground
|
Z33
|
GND
|
Ground
|
Z34
|
GND
|
Ground
|
Z35
|
GND
|
Ground
|
Z36
|
GND
|
Ground
|
Z37
|
GND
|
Ground
|
Z38
|
GND
|
Ground
|
Z39
|
GND
|
Ground
|
Z40
|
GND
|
Ground
|
Z41
|
GND
|
Ground
|
Z42
|
GND
|
Ground
|
Z43
|
GND
|
Ground
|
Z44
|
GND
|
Ground
|
Z45
|
GND
|
Ground
|
Z46
|
GND
|
Ground
|
Z47
|
GND
|
Ground
|
|
|
|
A1
|
5V
|
+5 VDC
|
A2
|
TCK
|
Test Clock
|
A3
|
INTA#
|
Interrupt A |
A4
|
BRSV
|
Bused Reserved (don"t use)
|
A5
|
BRSV
|
Bused Reserved (don"t use)
|
A6
|
REQ#
|
Request PCI transfer
|
A7
|
AD(30)
|
Address/Data 30
|
A8
|
AD(26)
|
Address/Data 26
|
A9
|
C/BE(3)#
|
Command: Byte Enable
|
A10
|
AD(21)
|
Address/Data 21
|
A11
|
AD(18)
|
Address/Data 18
|
A12
|
KEY
|
Keyed (no pin)
|
A13
|
KEY
|
Keyed (no pin)
|
A14
|
KEY
|
Keyed (no pin)
|
A15
|
3.3V
|
+3.3 VDC
|
A16
|
DEVSEL#
|
Device Select
|
A17
|
3.3V
|
+3.3 VDC
|
A18
|
SERR#
|
System Error
|
A19
|
3.3V
|
+3.3 VDC
|
A20
|
AD(12)
|
Address/Data 12
|
A21
|
3.3V
|
+3.3 VDC
|
A22
|
AD(7)
|
Address/Data 7)
|
A23
|
3.3V
|
+3.3 VDC
|
A24
|
AD(1)
|
Address/Data 1)
|
A25
|
5V
|
+5 VDC
|
A26
|
CLK1
|
Clock ?? MHz
|
A27
|
CLK2
|
Clock ?? MHz
|
A28
|
CLK4
|
Clock ?? MHz
|
A29
|
V(I/O)
|
+3.3 VDC or +5 VDC
|
A30
|
C/BE(5)#
|
Command: Byte Enable
|
A31
|
AD(63)
|
Address/Data 63
|
A32
|
AD(59)
|
Address/Data 59
|
A33
|
AD(56)
|
Address/Data 56
|
A34
|
AD(52)
|
Address/Data 52
|
A35
|
AD(49)
|
Address/Data 49
|
A36
|
AD(45)
|
Address/Data 45
|
A37
|
AD(42)
|
Address/Data 42
|
A38
|
AD(38)
|
Address/Data 38
|
A39
|
AD(35)
|
Address/Data 35
|
A40
|
BRSV
|
Bused Reserved (don"t use)
|
A41
|
BRSV
|
Bused Reserved (don"t use)
|
A42
|
BRSV
|
Bused Reserved (don"t use)
|
A43
|
USR
|
User Defined
|
A44
|
USR
|
User Defined
|
A45
|
USR
|
User Defined
|
A46
|
USR
|
User Defined
|
A47
|
USR
|
User Defined
|
|
|
|
B1
|
-12V
|
-12 VDC
|
B2
|
5V
|
+5 VDC
|
B3
|
INTB#
|
Interrupt B |
B4
|
GND
|
Ground
|
B5
|
BRSV
|
Bused Reserved (don"t use)
|
B6
|
GND
|
Ground
|
B7
|
AD(29)
|
Address/Data 29
|
B8
|
GND
|
Ground
|
B9
|
IDSEL
|
Initialization Device Select
|
B10
|
GND
|
Ground
|
B11
|
AD(17)
|
Address/Data 17
|
B12
|
KEY
|
Keyed (no pin)
|
B13
|
KEY
|
Keyed (no pin)
|
B14
|
KEY
|
Keyed (no pin)
|
B15
|
FRAME#
|
Address or Data phase
|
B16
|
GND
|
Ground
|
B17
|
SDONE
|
Snoop Done
|
B18
|
GND
|
Ground
|
B19
|
AD(15)
|
Address/Data 15
|
B20
|
GND
|
Ground
|
B21
|
AD(9)
|
Address/Data 9)
|
B22
|
GND
|
Ground
|
B23
|
AD(4)
|
Address/Data 4)
|
B24
|
5V
|
+5 VDC
|
B25
|
REQ64#
|
|
B26
|
GND
|
Ground
|
B27
|
CLK3
|
Clock ?? MHz
|
B28
|
GND
|
Ground
|
B29
|
BRSV
|
Bused Reserved (don"t use)
|
B30
|
GND
|
Ground
|
B31
|
AD(62)
|
Address/Data 62
|
B32
|
GND
|
Ground
|
B33
|
AD(55)
|
Address/Data 55
|
B34
|
GND
|
Ground
|
B35
|
AD(48)
|
Address/Data 48
|
B36
|
GND
|
Ground
|
B37
|
AD(41)
|
Address/Data 41
|
B38
|
GND
|
Ground
|
B39
|
AD(34)
|
Address/Data 34
|
B40
|
GND
|
Ground
|
B41
|
BRSV
|
Bused Reserved (don"t use)
|
B42
|
GND
|
Ground
|
B43
|
USR
|
User Defined
|
B44
|
USR
|
User Defined
|
B45
|
USR
|
User Defined
|
B46
|
USR
|
User Defined
|
B47
|
USR
|
User Defined
|
|
|
|
C1
|
TRST#
|
Test Logic Reset
|
C2
|
TMS
|
Test Mode Select
|
C3
|
INTC#
|
Interrupt C |
C4
|
V(I/O)
|
+3.3 VDC or +5 VDC
|
C5
|
RST
|
Reset
|
C6
|
3.3V
|
+3.3 VDC
|
C7
|
AD(28)
|
Address/Data 28
|
C8
|
V(I/O)
|
+3.3 VDC or +5 VDC
|
C9
|
AD(23)
|
Address/Data 23
|
C10
|
3.3V
|
+3.3 VDC
|
C11
|
AD(16)
|
Address/Data 16
|
C12
|
KEY
|
Keyed (no pin)
|
C13
|
KEY
|
Keyed (no pin)
|
C14
|
KEY
|
Keyed (no pin)
|
C15
|
IRDY#
|
Initiator Ready
|
C16
|
V(I/O)
|
+3.3 VDC or +5 VDC
|
C17
|
SBO#
|
Snoop Backoff
|
C18
|
3.3V
|
+3.3 VDC
|
C19
|
AD(14)
|
Address/Data 14
|
C20
|
V(I/O)
|
+3.3 VDC or +5 VDC
|
C21
|
AD(8)
|
Address/Data 8)
|
C22
|
3.3V
|
+3.3 VDC
|
C23
|
AD(3)
|
Address/Data 3)
|
C24
|
V(I/O)
|
+3.3 VDC or +5 VDC
|
C25
|
BRSV
|
Bused Reserved (don"t use)
|
C26
|
REQ1#
|
Request PCI transfer
|
C27
|
SYSEN#
|
|
C28
|
GNT3#
|
Grant
|
C29
|
C/BE(7)
|
Command: Byte Enable
|
C30
|
V(I/O)
|
+3.3 VDC or +5 VDC
|
C31
|
AD(61)
|
Address/Data 61
|
C32
|
V(I/O)
|
+3.3 VDC or +5 VDC
|
C33
|
AD(54)
|
Address/Data 54
|
C34
|
V(I/O)
|
+3.3 VDC or +5 VDC
|
C35
|
AD(47)
|
Address/Data 47
|
C36
|
V(I/O)
|
+3.3 VDC or +5 VDC
|
C37
|
AD(40)
|
Address/Data 40
|
C38
|
V(I/O)
|
+3.3 VDC or +5 VDC
|
C39
|
AD(33)
|
Address/Data 33
|
C40
|
FAL#
|
Power Supply Status FAL (CompactPCI specific)
|
C41
|
DEG#
|
Power Supply Status DEG (CompactPCI specific)
|
C42
|
PRST#
|
Push Button Reset (CompactPCI specific)
|
C43
|
USR
|
User Defined
|
C44
|
USR
|
User Defined
|
C45
|
USR
|
User Defined
|
C46
|
USR
|
User Defined
|
C47
|
USR
|
User Defined
|
|
|
|
D1
|
+12V
|
+12 VDC
|
D2
|
TDO
|
Test Data Output
|
D3
|
5V
|
+5 VDC
|
D4
|
INTP
|
|
D5
|
GND
|
Ground
|
D6
|
CLK
|
|
D7
|
GND
|
Ground
|
D8
|
AD(25)
|
Address/Data 25
|
D9
|
GND
|
Ground
|
D10
|
AD(20)
|
Address/Data 20
|
D11
|
GND
|
Ground
|
D12
|
KEY
|
Keyed (no pin)
|
D13
|
KEY
|
Keyed (no pin)
|
D14
|
KEY
|
Keyed (no pin)
|
D15
|
GND
|
Ground
|
D16
|
STOP#
|
Stop transfer cycle
|
D17
|
GND
|
Ground
|
D18
|
PAR
|
Parity for AD0-31 & C/BE0-3
|
D19
|
GND
|
Ground
|
D20
|
AD(11)
|
Address/Data 11
|
D21
|
M66EN
|
|
D22
|
AD(6)
|
Address/Data 6)
|
D23
|
5V
|
+5 VDC
|
D24
|
AD(0)
|
Address/Data 0)
|
D25
|
3.3V
|
+3.3 VDC
|
D26
|
GNT1#
|
Grant
|
D27
|
GNT2#
|
Grant
|
D28
|
REQ4#
|
Request PCI transfer
|
D29
|
GND
|
Ground
|
D30
|
C/BE(4)#
|
Command: Byte Enable
|
D31
|
GND
|
Ground
|
D32
|
AD(58)
|
Address/Data 58
|
D33
|
GND
|
Ground
|
D34
|
AD(51)
|
Address/Data 51
|
D35
|
GND
|
Ground
|
D36
|
AD(44)
|
Address/Data 44
|
D37
|
GND
|
Ground
|
D38
|
AD(37)
|
Address/Data 37
|
D39
|
GND
|
Ground
|
D40
|
REQ5#
|
Request PCI transfer
|
D41
|
GND
|
Ground
|
D42
|
REQ6#
|
Request PCI transfer
|
D43
|
USR
|
User Defined
|
D44
|
USR
|
User Defined
|
D45
|
USR
|
User Defined
|
D46
|
USR
|
User Defined
|
D47
|
USR
|
User Defined
|
|
|
|
E1
|
5V
|
+5 VDC
|
E2
|
TDI
|
Test Data Input
|
E3
|
INTD#
|
Interrupt D |
E4
|
INTS
|
|
E5
|
GNT#
|
Grant
|
E6
|
AD(31)
|
Address/Data 31
|
E7
|
AD(27)
|
Address/Data 27
|
E8
|
AD(24)
|
Address/Data 24
|
E9
|
AD(22)
|
Address/Data 22
|
E10
|
AD(19)
|
Address/Data 19
|
E11
|
C/BE(2)#
|
Command: Byte Enable
|
E12
|
KEY
|
Keyed (no pin)
|
E13
|
KEY
|
Keyed (no pin)
|
E14
|
KEY
|
Keyed (no pin)
|
E15
|
TRDY#
|
Target Ready
|
E16
|
LOCK#
|
Lock resource
|
E17
|
PERR#
|
Parity Error
|
E18
|
C/BE(1)#
|
Command: Byte Enable
|
E19
|
AD(13)
|
Address/Data 13
|
E20
|
AD(10)
|
Address/Data 10
|
E21
|
C/BE(0)#
|
Command: Byte Enable
|
E22
|
AD(5)
|
Address/Data 5)
|
E23
|
AD(2)
|
Address/Data 2)
|
E24
|
ACK64#
|
|
E25
|
5V
|
+5 VDC
|
E26
|
REQ2#
|
Request PCI transfer
|
E27
|
REQ3#
|
Request PCI transfer
|
E28
|
GNT4#
|
Grant
|
E29
|
C/BE(6)#
|
Command: Byte Enable
|
E30
|
PAR64
|
|
E31
|
AD(60)
|
Address/Data 60
|
E32
|
AD(57)
|
Address/Data 57
|
E33
|
AD(53)
|
Address/Data 53
|
E34
|
AD(50)
|
Address/Data 50
|
E35
|
AD(46)
|
Address/Data 46
|
E36
|
AD(43)
|
Address/Data 43
|
E37
|
AD(39)
|
Address/Data 39
|
E38
|
AD(36)
|
Address/Data 36
|
E39
|
AD(32)
|
Address/Data 32
|
E40
|
GNT5#
|
Grant
|
E41
|
BRSV
|
Bused Reserved (don"t use)
|
E42
|
GNT6#
|
Grant
|
E43
|
USR
|
User Defined
|
E44
|
USR
|
User Defined
|
E45
|
USR
|
User Defined
|
E46
|
USR
|
User Defined
|
E47
|
USR
|
User Defined
|
|
|
|
F1
|
GND
|
Ground
|
F2
|
GND
|
Ground
|
F3
|
GND
|
Ground
|
F4
|
GND
|
Ground
|
F5
|
GND
|
Ground
|
F6
|
GND
|
Ground
|
F7
|
GND
|
Ground
|
F8
|
GND
|
Ground
|
F9
|
GND
|
Ground
|
F10
|
GND
|
Ground
|
F11
|
GND
|
Ground
|
F12
|
KEY
|
Keyed (no pin)
|
F13
|
KEY
|
Keyed (no pin)
|
F14
|
KEY
|
Keyed (no pin)
|
F15
|
GND
|
Ground
|
F16
|
GND
|
Ground
|
F17
|
GND
|
Ground
|
F18
|
GND
|
Ground
|
F19
|
GND
|
Ground
|
F20
|
GND
|
Ground
|
F21
|
GND
|
Ground
|
F22
|
GND
|
Ground
|
F23
|
GND
|
Ground
|
F24
|
GND
|
Ground
|
F25
|
GND
|
Ground
|
F26
|
GND
|
Ground
|
F27
|
GND
|
Ground
|
F28
|
GND
|
Ground
|
F29
|
GND
|
Ground
|
F30
|
GND
|
Ground
|
F31
|
GND
|
Ground
|
F32
|
GND
|
Ground
|
F33
|
GND
|
Ground
|
F34
|
GND
|
Ground
|
F35
|
GND
|
Ground
|
F36
|
GND
|
Ground
|
F37
|
GND
|
Ground
|
F38
|
GND
|
Ground
|
F39
|
GND
|
Ground
|
F40
|
GND
|
Ground
|
F41
|
GND
|
Ground
|
F42
|
GND
|
Ground
|
F43
|
GND
|
Ground
|
F44
|
GND
|
Ground
|
F45
|
GND
|
Ground
|
F46
|
GND
|
Ground
|
F47
|
GND
|
Ground
|
Sources:
CompactPCI specifications v1.0
at CompactPCI"s homepage
Sources: Mark Sokos PCI page
Sources: "Inside the PCI Local Bus" by Guy
W. Kendall, Byte, February 1994 v 19 p. 177-180
Sources: "The Indispensible PC Hardware Book"
by Hans-Peter Messmer, ISBN 0-201-8769-3
This section does not currently contain so much in
depth information as I would like.
For a copy of the full CompactPCI standard, contact:
PCI Industrial Computer Manufacturers Group (PICMG)
c/o Roger Communications
301 Edgewater place
Suite 220
Wakewater
MA01880
Phone: 1-617-224-1100
Fax: 1-617-224-1239
Overview:
A CompactPCI system is composed of up to eight CompactPCI
card locations:
-
One System Slot
-
Up to seven Peripheral Slots
The connector has 7 columns with 47 rows. They are
divided into groups:
-
Row 1-25: 32-bit PCI
-
Row 26-47: Additional pins for 64-bit PCI (System Slot
boards must use it).
-
Row 26-28 and 40-42: Primarily implemented on System
Slot boards.
The following signals must be terminated:
-
AD0-31
-
C/BE0#-C/BE3#
-
PAR
-
FRAME#
-
IRDY#
-
TRDY#
-
STOP#
-
LOCK#
-
IDSEL
-
DEVSEL#
-
PERR#
-
SERR#
-
RST#
The following signals must be terminated if used:
-
INTA#
-
INTB#
-
INTC#
-
INTD#
-
SB0#
-
SDOBE
-
AD32-AD63
-
C/BE4#-C/BE7#
-
REQ64#
-
ACK64#
-
PAR64#
The following signals do no require a stub termination:
-
CLK
-
REQ#
-
GNT#
-
TDI#
-
TDO
-
TCK
-
TMS
-
TRST#
The System Slot board must pullup the following signals
(even if not used):
Connector:
1 |
GND
|
5V
|
-12V
|
TRST#
|
12V
|
5V
|
GND
|
2 |
GND
|
TCK
|
5V
|
TMS
|
DO
|
TDI
|
GND
|
3 |
GND
|
INTA#
|
INTB#
|
INTC#
|
5V
|
INTD#
|
GND
|
4 |
GND
|
BRSV
|
GND
|
V(I/O)
|
INTP
|
INTS
|
GND
|
5 |
GND
|
BRSV
|
BRSV
|
RST
|
GND
|
GNT#
|
GND
|
6 |
GND
|
REQ#
|
GND
|
3.3V
|
CLK
|
AD(31)
|
GND
|
7 |
GND
|
AD(30)
|
AD(29)
|
AD(28)
|
GND
|
AD(27)
|
GND
|
8 |
GND
|
AD(26)
|
GND
|
V(I/O)
|
AD(25)
|
AD(24)
|
GND
|
9 |
GND
|
C/BE(3)#
|
IDSEL
|
AD(23)
|
GND
|
AD(22)
|
GND
|
10 |
GND
|
AD(21)
|
GND
|
3.3V
|
AD(20)
|
AD(19)
|
GND
|
11 |
GND
|
AD(18)
|
AS(17)
|
AD(16)
|
GND
|
C/BE(2)#
|
GND
|
12 |
KEY
|
KEY
|
KEY
|
KEY
|
KEY
|
KEY
|
KEY
|
13 |
KEY
|
KEY
|
KEY
|
KEY
|
KEY
|
KEY
|
KEY
|
14 |
KEY
|
KEY
|
KEY
|
KEY
|
KEY
|
KEY
|
KEY
|
15 |
GND
|
3.3V
|
FRAME#
|
IRDY#
|
GND
|
TRDY#
|
GND
|
16 |
GND
|
DEVSEL#
|
GND
|
V(I/O)
|
STOP#
|
LOCK#
|
GND
|
17 |
GND
|
3.3V
|
SDONE
|
SBO#
|
GND
|
PERR#
|
GND
|
18 |
GND
|
SERR#
|
GND
|
3.3V
|
PAR
|
C/BE(1)#
|
GND
|
19 |
GND
|
3.3V
|
AD(15)
|
AD(14)
|
GND
|
AD(13)
|
GND
|
20 |
GND
|
AD(12)
|
GND
|
V(I/O)
|
AD(11)
|
AD(10)
|
GND
|
21 |
GND
|
3.3V
|
AD(9)
|
AD(8)
|
M66EN
|
C/BE(0)#
|
GND
|
22 |
GND
|
AD(7)
|
GND
|
3.3V
|
AD(6)
|
AD(5)
|
GND
|
23 |
GND
|
3.3V
|
AD(4)
|
AD(3)
|
5V
|
AD(2)
|
GND
|
24 |
GND
|
AD(1)
|
5V
|
V(I/O)
|
AD(0)
|
ACK64#
|
GND
|
25 |
GND
|
5V
|
REQ64#
|
BRSV
|
3.3V
|
5V
|
GND
|
26 |
GND
|
CLK1
|
GND
|
REQ1#
|
GNT1#
|
REQ2#
|
GND
|
27 |
GND
|
CLK2
|
CLK3
|
SYSEN#
|
GNT2#
|
REQ3#
|
GND
|
28 |
GND
|
CLK4
|
GND
|
GNT3#
|
REQ4#
|
GNT4#
|
GND
|
29 |
GND
|
V(I/O)
|
BRSV
|
C/BE(7 ) |
GND
|
C/BE(6)#
|
GND
|
30 |
GND
|
C/BE(5)#
|
GND
|
V(I/O)
|
C/BE(4)#
|
PAR64
|
GND
|
31 |
GND
|
AD(63)
|
AD(62)
|
AD(61)
|
GND
|
AD(60)
|
GND
|
32 |
GND
|
AD(59)
|
GND
|
V(I/O)
|
AD(58)
|
AD(57)
|
GND
|
33 |
GND
|
AD(56)
|
AD(55)
|
AD(54)
|
GND
|
AD(53)
|
GND
|
34 |
GND
|
AD(52)
|
GND
|
V(I/O)
|
AD(51)
|
AD(50)
|
GND
|
35 |
GND
|
AD(49)
|
AD(48)
|
AD(47)
|
GND
|
AD(46)
|
GND
|
36 |
GND
|
AD(45)
|
GND
|
V(I/O)
|
AD(44)
|
AD(43)
|
GND
|
37 |
GND
|
AD(42)
|
AD(41)
|
AD(40)
|
GND
|
AD(39)
|
GND
|
38 |
GND
|
AD(38)
|
GND
|
V(I/O)
|
AD(37)
|
AD(36)
|
GND
|
39 |
GND
|
AD(35)
|
AD(34)
|
AD(33)
|
GND
|
AD(32)
|
GND
|
40 |
GND
|
BRSV
|
GND
|
FAL#
|
REQ5#
|
GNT5#
|
GND
|
41 |
GND
|
BRSV
|
BRSV
|
DEG#
|
GND
|
BRSV
|
GND
|
42 |
GND
|
BRSV
|
GND
|
PRST#
|
REQ6#
|
GNT6#
|
GND
|
43 |
GND
|
USR
|
USR
|
USR
|
USR
|
USR
|
GND
|
44 |
GND
|
USR
|
USR
|
USR
|
USR
|
USR
|
GND
|
45 |
GND
|
USR
|
USR
|
USR
|
USR
|
USR
|
GND
|
46 |
GND
|
USR
|
USR
|
USR
|
USR
|
USR
|
GND
|
47 |
GND
|
USR
|
USR
|
USR
|
USR
|
USR
|
GND
|
|
Z |
A |
B |
C |
D |
E |
F |
Signal Descriptions:
PRST
Push Button Reset.
DEG
Power Supply Status DEG
FAL
Power Supply Status FAL
SYSEN
System Slot Identification
cPCI is electrically identical to the PCI specification, except it uses the
Euro (VME) card 3U/6U format with 2mm connectors. The cPCI bus uses 8, 16, 32,
or 64 bit transfers with up to 264MBps. 64 bit PCI transfers may be used in
either 3U or 6U size cards. 6U cards contain additional pins for user defined
I/O.
3U card dimensions are 100mm x 160mm x 1.6mm thick, 6U card dimensions are 233.35mm
x 160mm x 1.6mm thick.
The PCI spec defines the Electrical requirements for the interface. No bus
terminations are specified, the bus relies on signal reflection to achieve level
threshold. The first version of the PCI bus ran at 33MHz with a 32 bit bus (133MBps),
then added 64 bits at 33MHz (266MBps). The current version runs at 66MHz with
a 64 bit bus (532Mbps). The PCI bus operates either synchronously or asynchronously
with the "Mother Board" bus rate. While operating asynchronously the
bus will operate at any frequency from 66MHz down to (and including) 0Hz. Flow
control is added to allow the bus to operate with slower devices on the bus,
allowing the bus to operate at their speed. PCI is an unterminated bus, the
signals relay on signal reflections to attain their final value. The PCI specification
has been port-ed to a number of other form factors.
Addition features of cPCI include; live insertion support (Hot-Swap), supports
two independent buses on the backplane (on different connectors), and soon Infiniband,
Ethernet, and Star Fabric support (Switched Fabric based systems).
PXI defines cPCI for Instrumentation adding additional enhancements, with the
same form factor as cPCI. PXI adds additional signals and chassis requirements
just like VXI adds to VME. Unlike VXI, PXI does not require that the card be
enclosed in a metal shield |