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Processor Slots

After introducing the Pentium Pro with its integrated L2 cache, Intel discovered that the physical package it chose was very costly to produce. Intel was looking for a way to easily integrate cache and possibly other components into a processor package, and it came up with a cartridge or board design as the best way to do this. In order to accept its new cartridges, Intel designed two different types of slots that could be used on motherboards.

Slot 1 is a 242-pin slot that is designed to accept Pentium II, Pentium III, and most Celeron processors. Slot 2 is a more sophisticated 330-pin slot that is designed for the Pentium II and III Xeon processors, which are primarily for workstations and servers. Besides the extra pins, the biggest difference between Slot 1 and Slot 2 is the fact that Slot 2 was designed to host up to four-way or more processing in a single board. Slot 1 only allows single or dual processing functionality.

Note that Slot 2 is also called SC330, which stands for Slot Connector with 330 pins.

Slot 1 (SC242)

Slot 1, also called SC242 (Slot Connector 242 pins), is used by the SEC (Single Edge Cartridge) design used with the cartridge-type Pentium II/III and Celeron processors. Inside the cartridge is a substrate card that includes the processor and L2 cache. Unlike the Pentium Pro, the L2 cache was mounted on the circuit board and not within the same chip package as the processor. This allowed Intel to use aftermarket SRAM chips instead of making them internally and also allowed it to make processors with different amounts of cache easily. For example, the original Celeron was created by taking a Pentium II and simply leaving out the external cache chips. Figure 3.22 shows the Slot 1 connector dimensions and pin layout.

See "Single Edge Contact (SEC) and Single Edge Processor (SEP) Packaging."

Figure 3.22 Slot 1 connector dimensions and pin layout.

Table 3.13 lists the names of each of the pins in the Slot 1 connector.

Table 3.13 Signal Listing in Order by Pin Number

Pin No.

Pin Name

A1

VCC_VTT

A2

GND

A3

VCC_VTT

A4

IERR#

A5

A20M#

A6

GND

A7

FERR#

A8

IGNNE#

A9

TDI

A10

GND

A11

TDO

A12

PWRGOOD

A13

TESTHI

A14

GND

A15

THERMTRIP#

A16

Reserved

A17

LINT[0]/INTR

A18

GND

A19

PICD[0]

A20

PREQ#

A21

BP#[3]

A22

GND

A23

BPM#[0]

A24

BINIT#

A25

DEP#[0]

A26

GND

A27

DEP#[1]

A28

DEP#[3]

A29

DEP#[5]

A30

GND

A31

DEP#[6]

A32

D#[61]

A33

D#[55]

A34

GND

A35

D#[60]

A36

D#[53]

A37

D#[57]

A38

GND

A39

D#[46]

A40

D#[49]

A41

D#[51]

A42

GND

A43

D#[42]

A44

D#[45]

A45

D#[39]

A46

GND

A47

Reserved

A48

D#[43]

A49

D#[37]

A50

GND

A51

D#[33]

A52

D#[35]

A53

D#[31]

A54

GND

A55

D#[30]

A56

D#[27]

A57

D#[24]

A58

GND

A59

D#[23]

A60

D#[21]

A61

D#[16]

A62

GND

A63

D#[13]

A64

D#[11]

A65

D#[10]

A66

GND

A67

D#[14]

A68

D#[9]

A69

D#[8]

A70

GND

A71

D#[5]

A72

D#[3]

A73

D#[1]

A74

GND

A75

BCLK

A76

BR0#

A77

BERR#

A78

GND

A79

A#[33]

A80

A#[34]

A81

A#[30]

A82

GND

A83

A#[31]

A84

A#[27]

A85

A#[22]

A86

GND

A87

A#[23]

A88

Reserved

A89

A#[19]

A90

GND

A91

A#[18]

A92

A#[16]

A93

A#[13]

A94

GND

A95

A#[14]

A96

A#[10]

A97

A#[5]

A98

GND

A99

A#[9]

A100

A#[4]

A101

BNR#

A102

GND

A103

BPRI#

A104

TRDY#

A105

DEFER#

A106

GND

A107

REQ#[2]

A108

REQ#[3]

A109

HITM#

A110

GND

A111

DBSY#

A112

RS#[1]

A113

Reserved

A114

GND

A115

ADS#

A116

Reserved

A117

AP#[0]

A118

GND

A119

VID[2]

A120

VID[1]

A121

VID[4]

B1

EMI

B2

FLUSH#

B3

SMI#

B4

INIT#

B5

VCC_VTT

B6

STPCLK#

B7

TCK

B8

SLP#

B9

VCC_VTT

B10

TMS

B11

TRST#

B12

Reserved

B13

VCC_CORE

B14

Reserved

B15

Reserved

B16

LINT[1]/NMI

B17

VCC_CORE

B18

PICCLK

B19

BP#[2]

B20

Reserved

B21

BSEL#

B22

PICD[1]

B23

PRDY#

B24

BPM#[1]

B25

VCC_CORE

B26

DEP#[2]

B27

DEP#[4]

B28

DEP#[7]

B29

VCC_CORE

B30

D#[62]

B31

D#[58]

B32

D#[63]

B33

VCC_CORE

B34

D#[56]

B35

D#[50]

B36

D#[54]

B37

VCC_CORE

B38

D#[59]

B39

D#[48]

B40

D#[52]

B41

EMI

B42

D#[41]

B43

D#[47]

B44

D#[44]

B45

VCC_CORE

B46

D#[36]

B47

D#[40]

B48

D#[34]

B49

VCC_CORE

B50

D#[38]

B51

D#[32]

B52

D#[28]

B53

VCC_CORE

B54

D#[29]

B55

D#[26]

B56

D#[25]

B57

VCC_CORE

B58

D#[22]

B59

D#[19]

B60

D#[18]

B61

EMI

B62

D#[20]

B63

D#[17]

B64

D#[15]

B65

VCC_CORE

B66

D#[12]

B67

D#[7]

B68

D#[6]

B69

VCC_CORE

B70

D#[4]

B71

D#[2]

B72

D#[0]

B73

VCC_CORE

B74

RESET#

B75

BR1#

B76

FRCERR

B77

VCC_CORE

B78

A#[35]

B79

A#[32]

B80

A#[29]

B81

EMI

B82

A#[26]

B83

A#[24]

B84

A#[28]

B85

VCC_CORE

B86

A#[20]

B87

A#[21]

B88

A#[25]

B89

VCC_CORE

B90

A#[15]

B91

A#[17]

B92

A#[11]

B93

VCC_CORE

B94

A#[12]

B95

A#[8]

B96

A#[7]

B97

VCC_CORE

B98

A#[3]

B99

A#[6]

B100

EMI

B101

SLOTOCC#

B102

REQ#[0]

B103

REQ#[1]

B104

REQ#[4]

B105

VCC_CORE

B106

LOCK#

B107

DRDY#

B108

RS#[0]

B109

VCC5

B110

HIT#

B111

RS#[2]

B112

Reserved

B113

VCC_L2

B114

RP#

B115

RSP#

B116

AP#[1]

B117

VCC_L2

B118

AERR#

B119

VID[3]

B120

VID[0]

B121

VCC_L2


Slot 2 (SC330)

Slot 2, otherwise called SC330 (Slot Connector 330 pins) is used on high-end motherboards that support the Pentium II and III Xeon processors. Figure 3.23 shows the Slot 2 connector.

Figure 3.23 Slot 2 (SC330) connector dimensions and pin layout.

The Xeon processors are designed in a cartridge similar to, but larger than, that used for the standard Pentium II/III. Figure 3.24 shows the Xeon cartridge.

Motherboards featuring Slot 2 are primarily found in higher-end systems such as workstations or servers, which use the Xeon processors. These are Intel's high-end chips, which differ from the standard Pentium II/III mainly by virtue of having full-core speed L2 cache, and in some versions more of it.

Figure 3.24 Pentium II/III Xeon cartridge.

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