View source for Slot 1

{{short description|Physical and electrical specification for the connector used by some Intel microprocessors}}
{{about|a PC processor socket|SLOT-1 on a Nintendo DS|Nintendo DS and 3DS storage devices}}
{{Lead too short|date=February 2024}}
{{CPU socket
| name = Slot 1
| image = [[image:Asus P3C2000 - Slot 1-8626.jpg|290px]]
| type = Slot
| formfactors =
* Single Edge Contact Cartridge ([[Pentium II]])
* Single Edge Contact Cartridge 2 ([[Pentium II]], [[Pentium III]])
* Single Edge Processor Package ([[Celeron]])
| contacts = 242<ref>{{cite web|url=http://users.erols.com/chare/sockets.htm|title=CPU Sockets Chart|accessdate=2009-03-31|publisher=erols.com|archive-date=2009-03-22|archive-url=https://web.archive.org/web/20090322202532/http://users.erols.com/chare/sockets.htm|url-status=dead}}</ref>
| protocol = [[AGTL+]]
| fsb = 66, 100, and (on third-party chipsets) 133 MHz
| voltage = 1.3 to 3.50&nbsp;V
| processors = [[Pentium II]]: 233–450&nbsp;MHz<br />
[[Intel Celeron|Celeron]]: 266–433&nbsp;MHz<br />
[[Pentium III]]: 450&nbsp;MHz–1.13&nbsp;GHz<br />
(A [[Slotket]] makes following Socket 370 CPUs usable:<br />
[[Celeron]] and [[Pentium III]] to 1,400&nbsp;MHz,<br />
[[Cyrix III|VIA Cyrix III]]: 350–733&nbsp;MHz,<br />
[[VIA C3]]: 733–1,200&nbsp;MHz<br />
Slotkets also made it possible to use some Pentium Pro CPUs for Socket 8 using the same method.)
| predecessor = [[Socket 7]]
| successor = [[Socket 370]]
}}
[[File:Pentium II SECC cartridge on motherboard.jpg|thumb|Pentium II SECC form installed into Slot 1]]
'''Slot 1''' refers to the physical and electrical specification for the connector used by some of [[Intel Corporation|Intel]]'s microprocessors, including the [[Pentium Pro]], [[Celeron]], [[Pentium II]] and the [[Pentium III]].  Both single and dual processor configurations were implemented.

Intel reverted to the traditional socket interface with the release of [[Socket 370]] in 1999.

== General ==
With the introduction of the Pentium II CPU, the need for greater access for testing had made the transition from socket to slot necessary.  Previously with the [[Pentium Pro]], Intel had combined processor and cache dies in the same [[Socket 8]] package.  These were connected by a full-speed bus, resulting in significant performance benefits.  Unfortunately, this method required that the two components be bonded together early in the production process, before testing was possible.  As a result, a single, tiny flaw in either die made it necessary to discard the entire assembly, causing low production yield and high cost.{{citation needed|date=November 2020}}<!--please don't use other Wikipedia articles as references-->

Intel subsequently designed a circuit board where the CPU and cache remained closely integrated, but were mounted on a [[printed circuit board]], called a Single-Edged Contact Cartridge (SECC). The CPU and cache could be tested separately, before final assembly into a package, reducing cost and making the CPU more attractive to markets other than that of high-end servers. These cards could also be easily plugged into a Slot 1, thereby eliminating the chance for pins of a typical CPU to be bent or broken when installing in a socket.

[[File:AMD Slot A (left) and Intel Slot 1 (right)-flickr - by - flickrsven.jpg|thumb|A Slot A CPU on the left compared to a Slot 1 CPU (connector rotated by 180 degrees)]]

The form factor used for Slot 1 was a 5-inch-long, 242-contact [[edge connector]] named SC242. To prevent the cartridge from being inserted the wrong way, the slot was keyed to allow installation in only one direction. The SC242 was later used for AMD's [[Slot A]] as well, and while the two slots were identical mechanically, they were electrically incompatible. To discourage Slot A users from trying to install a Slot 1 CPU, the connector was rotated 180 degrees on Slot A motherboards. This also allowed motherboard manufacturers to save costs by stocking the same part for both Slot 1 and Slot A assemblies.

With the new Slot 1, Intel added support for [[symmetric multiprocessing]] (SMP). A maximum of two Pentium II or Pentium III CPUs can be used in a dual slot motherboard. The Celeron does not have official SMP support.

There are also converter cards, known as [[Slotket]]s, which hold a [[Socket 8]] so that a [[Pentium Pro]] CPU can be used with Slot 1 motherboards.<ref>{{cite web |url=http://usenet.p2preactor.com/index-t-1246309.html |archive-url=https://web.archive.org/web/20070929055735/http://usenet.p2preactor.com/index-t-1246309.html |url-status=dead |archivedate=2007-09-29 |title=PPro on a BX?-Usenet Gateway }}</ref> These specific converters, however, are rare. Another kind of slotket allows using a Socket 370 CPU in a Slot 1. These are generally more common than Socket 8 to Slot<ref>{{Cite web |url=https://slexus.com/ |title=Archived copy |access-date=2024-04-04 |archive-date=2024-04-03 |archive-url=https://web.archive.org/web/20240403130850/https://slexus.com/ |url-status=dead }}</ref> 1 slotkets. Many of these latter devices are equipped with their own voltage regulator modules, in order to supply the new CPU with a lower core voltage, which the motherboard would not otherwise allow.

== Form factors ==
[[File:Pentium II front.jpg|thumb|Intel Pentium II CPU in SECC form factor]]
[[File:PentiumIII SECC2.jpg|thumb|Pentium III (Katmai) in SECC2: CPU at center, two chips at right are cache]]
[[File:Celeron 300A.jpg|thumb|Celeron in SEPP: CPU at center (under heat spreader), surrounding chips are resistors and bypass capacitors]]

The Single Edge Contact Cartridge, or "'''SECC'''", was used at the beginning of the Slot 1-era for Pentium II CPUs. Inside the cartridge, the CPU itself is enclosed in a hybrid plastic and metal case. The back of the housing is plastic and has several markings on it: the name, "Pentium II"; the Intel logo; a [[hologram]]; and the model number. The front consists of a black [[Anodizing|anodized]] aluminum plate, which is used to hold the CPU cooler. The SECC form is very solid, because the CPU itself is resting safely inside the case. As compared to socket-based CPUs, there are no pins that can be bent, and the CPU is less likely to be damaged by improper installation of a cooler.

Following SECC, the '''SEPP'''-form (Single Edge Processor Package) appeared on the market. It was designed for lower-priced Celeron CPUs. This form lacks a case entirely, consisting solely of the printed-circuit board holding the components.

A form factor called '''SECC2''' was used for late Pentium II and Pentium III CPUs for Slot 1, which was created to accommodate the switch to [[flip chip]] packaging.<ref>[https://web.archive.org/web/20081001190920/http://www.tomshardware.com/reviews/overclocking-special,94-2.html]</ref> Only the front plate was carried over, the coolers were now mounted straight to the PCB and exposed CPU die and are, as such, incompatible with SECC cartridges.

== History ==
Historically, there are three platforms for the Intel [[P6 (microarchitecture)|P6]] CPUs: Socket 8, Slot 1 and Socket 370.

Slot 1 is a successor to [[Socket 8]]. While the Socket 8 CPUs (Pentium Pro) directly had the L2-cache embedded into the CPU, it is located (outside of the core) on a circuit board shared with the core itself. The exception is later Slot 1 CPUs with the [[Coppermine (microprocessor)|Coppermine]] core which have the L2-cache embedded into the die.

In the beginning of 2000, around the time the Coppermine Pentium III CPUs with [[Flip-chip pin grid array|FC-PGA]] housing were already commonplace, Slot 1 was being gradually phased out in favor of [[Socket 370]], well after Intel started to offer both Socket 370 and Slot 1 CPUs at the same time since late 1998. Socket 370 was initially made for low-cost Celeron processors starting with the [[Celeron#Mendocino|Mendocino]] Celerons, while Slot 1 was thought of as a platform for the more expensive Pentium II and early Pentium III models. Both cache and core were embedded into the die.

Slot 1 also obsoleted the old [[Socket 7]] as the standard platform for home users, at least regarding Intel. After superseding the Intel [[P5 (microarchitecture)|P5]] [[Pentium MMX]] CPU in the late 1990s, Intel had completely left the Socket 7 market.

== Chipsets and officially supported CPUs<ref>List of Intel chipsets</ref><ref>List of VIA chipsets</ref> ==
[[File:KL Socket370 Slot1 Adapter.jpg|thumb|Slot 1/Socket 370 Converter]]
[[File:KL Socket8 Slot1 Adapter.jpg|thumb|Slot 1/Socket 8 Converter]]

=== Intel 440FX <ref>Intel Corporation: ''[http://www.intel.com/design/chipsets/datashts/29054901.pdf 440FX PCIset Datasheet]''</ref> ===
* Introduced in: May 6, 1996
* [[Front Side Bus|FSB]]: 66&nbsp;MHz
* [[Programmed input/output|PIO]]/[[WDMA (computer)|WDMA]]
* Supported RAM type: [[Dynamic random access memory#Extended data out DRAM (EDO DRAM)|EDO-DRAM]]
* Supported CPUs:
** [[Pentium Pro]]
** [[Pentium II]] with 66&nbsp;MHz FSB
** [[Celeron]] (Covington, Mendocino)
* Used in both Socket 8 (Pentium Pro) and Slot 1 (Pentium II, early Celerons)
* Does not support [[Accelerated Graphics Port|AGP]] or [[SDRAM]], as it predates the introduction of said technologies
* Allowed up to two CPUs for [[Symmetric multiprocessor system|SMP]]

=== Intel 440LX <ref>Intel Corporation: ''[http://download.intel.com/design/chipsets/designex/29765101.pdf 440LX AGPset Design Guide]{{dead link|date=May 2018 |bot=InternetArchiveBot |fix-attempted=yes }}''</ref> ===
* Introduced in: August 27, 1997
* FSB: 66&nbsp;MHz
* Supported RAM type: EDO-DRAM, [[SDRAM]]
* Supported CPUs: Pentium II, Celeron
* [[Accelerated Graphics Port|AGP]] 2× Mode
* [[AT Attachment#UDMA and ATA-4|UDMA/33]]
** [[Pentium II]] with 66&nbsp;MHz FSB
** [[Celeron]] (Covington, Mendocino)
* Introduced support for [[Accelerated Graphics Port|AGP]] and [[SDRAM]]
* Allowed up to two CPUs for [[Symmetric multiprocessor system|SMP]]

=== Intel 440EX <ref>Intel Corporation: ''[http://download.intel.com/design/chipsets/designex/29063701.pdf 440EX AGPset Design Guide]'' {{webarchive|url=https://web.archive.org/web/20160901000000*/http://download.intel.com/design/chipsets/designex/29063701.pdf |date=2016-09-01 }}''</ref> ===
* Introduced in: April, 1998
* FSB: 66&nbsp;MHz
* Supported RAM type: EDO-DRAM, [[SDRAM]]
* Supported CPUs: Pentium II, Celeron
* [[Accelerated Graphics Port|AGP]] 2× Mode
* [[AT Attachment#UDMA and ATA-4|UDMA/33]]
** [[Pentium II]] with 66&nbsp;MHz FSB
** [[Celeron]] (Covington, Mendocino)
* Same specifications as 440LX, but memory support limited to 256 MB and no SMP support.

=== Intel 440BX <ref>Intel Corporation: ''[http://download.intel.com/design/chipsets/designex/29063401.pdf 440BX AGPset Design Guide] {{webarchive|url=https://web.archive.org/web/20121004031031/http://download.intel.com/design/chipsets/designex/29063401.pdf |date=2012-10-04 }}''</ref> ===
* Introduced in: April 1998
* FSB: 66 and 100&nbsp;MHz (some motherboards supported overclocking to 133&nbsp;MHz, allowing usage of Socket 370 CPUs using a [[Slotket|Slocket]])
* AGP 2× Mode (max aperture size 32 or 64 MB)
* UDMA/33
* Supported RAM types: [[SDRAM]] ([[PC66]] and [[PC100]], [[PC133]] with overclocking) up to 4 DIMMs of 256 MB
* Supported CPUs:
** [[Pentium II]] with 66 and 100&nbsp;MHz FSB
** [[Pentium III]] with 100&nbsp;MHz FSB (133 with overclocking)
** [[Intel Celeron|Celeron]] (Covington, Mendocino, Coppermine)
* Allowed up to two CPUs for [[Symmetric multiprocessor system|SMP]]

=== Intel 440ZX ===
* Introduced in: November 1998
* FSB: 66 and 100&nbsp;MHz (some motherboards supported overclocking to 133&nbsp;MHz, allowing usage of Socket 370 CPUs using a [[Slotket|Slocket]])
* AGP 2× Mode
* UDMA/33
* Supported RAM types: [[SDRAM]] ([[PC66]] and [[PC100]], [[PC133]] with overclocking), up to 2 DIMMs of 256 MB
* Supported CPUs:
** [[Pentium II]] with 66 and 100&nbsp;MHz FSB
** [[Pentium III]] with 100&nbsp;MHz FSB (133 with overclocking)
** [[Intel Celeron|Celeron]] (Covington, Mendocino, Coppermine)

=== Intel 810 ===
* Introduced in: 1999
* FSB: 66 and 100&nbsp;MHz
* No external AGP
* Intel i752 based graphics
* UDMA/66 (UDMA/33 with ICH0)
* Supported RAM types: PC100 [[SDRAM]]
* Supported CPUs:
** [[Pentium II]] with 66 and 100&nbsp;MHz FSB
** [[Pentium III]] with 100&nbsp;MHz FSB (133 with overclocking)
** [[Intel Celeron|Celeron]] (Covington, Mendocino, Coppermine)

=== Intel 820/820E (Camino) ===
* Introduced in: November 1999
* FSB: 100 and 133&nbsp;MHz
* AGP 4× Mode
* UDMA/66 (i820), UDMA/100 (i820E)
* Supported RAM types: [[RDRAM]], [[SDRAM]] (PC100 via MTH)
* Supported CPUs: All FSB 100/133 Slot 1 CPUs
* Allowed up to two CPUs for [[Symmetric multiprocessor system|SMP]]

=== Intel 840 ===
* Introduced in: November 1999
* FSB: 100 and 133&nbsp;MHz
* AGP 4× Mode
* UDMA/66 (i820), UDMA/100 (i820E)
* Supported RAM types: Dual Channel [[RDRAM]], [[SDRAM]] (PC100 via MTH)
* Supported CPUs: All FSB 100/133 Slot 1 CPUs
* Allowed up to two CPUs for [[Symmetric multiprocessor system|SMP]]

=== VIA Apollo Pro / Pro II / Pro+ ===
* Introduced in: May 1998 (Pro Plus: Dec 1998)
* FSB: 66, 100&nbsp;MHz (some motherboards supported overclocking to 133&nbsp;MHz, allowing usage of Socket 370 CPUs using a [[Slotket|Slocket]])
* AGP 2× Mode
* UDMA/33 (VT82C586B/VT82C596A), UDMA/66 (VT82C596B)
*Supported RAM types: PC66/100 [[SDRAM]] up to 1536 MB
* Supported CPUs:
** [[Pentium Pro]] with 66&nbsp;MHz FSB
** [[Pentium II]] with 66 and 100&nbsp;MHz FSB
** [[Pentium III]] with 100&nbsp;MHz FSB (133 with overclocking)
** [[Intel Celeron|Celeron]] (Covington, Mendocino, Coppermine)

=== VIA Apollo Pro 133 ===
* Introduced in: July 1999
* FSB: 66, 100, and 133&nbsp;MHz
* AGP 2× Mode
* UDMA/33 (VT82C596A), UDMA/66 (VT82C596B/VT82C686A), UDMA/100 (VT82C686B)
*Supported RAM types: PC66/100/133 [[SDRAM]] up to 1536 MB
* Supported CPUs: All Slot 1 CPUs

=== VIA Apollo Pro 133A ===
* Introduced in: Oct 1999
* FSB: 66, 100, and 133&nbsp;MHz
* AGP 4× Mode
* UDMA/66 (VT82C596B/VT82C686A), UDMA/100 (VT82C686B)
*Supported RAM types: PC66/100/133 [[SDRAM]] up to 2048 MB
* Supported CPUs: All Slot 1 CPUs
* Allowed up to two CPUs for [[Symmetric multiprocessor system|SMP]]

=== SiS 5600 (SiS 600) ===
* Introduced in: November 1998
* FSB: 66 and 100&nbsp;MHz 
* AGP 2× Mode
* UDMA/33
* Supported RAM types: PC66/100 [[SDRAM]] up to 1536 MB
* Supported CPUs:
** [[Pentium II]] with 66 and 100&nbsp;MHz FSB
** [[Pentium III]] with 100&nbsp;MHz FSB 
** [[Intel Celeron|Celeron]] (Covington, Mendocino, Coppermine)

=== SiS 620 ===
* Introduced in: April 1999
* FSB: 66 and 100&nbsp;MHz 
* No external AGP port
*SiS 6326 based Integrated Graphics
* UDMA/33
* Supported RAM types: PC66/100 [[SDRAM]] up to 1536 MB
* Supported CPUs:
** [[Pentium II]] with 66 and 100&nbsp;MHz FSB
** [[Pentium III]] with 100&nbsp;MHz FSB 
** [[Intel Celeron|Celeron]] (Covington, Mendocino, Coppermine)

==See also==
* [[Slot A]]
* [[Slot 2]]
* [[List of Intel microprocessors]]
* [[Slotket]]

== References ==
<references/>

== External links ==
{{Commons category}}
* [https://web.archive.org/web/20060622200013/http://developer.intel.com/design/pentiumiii/datashts/24445209.pdf Intel's detailed Slot 1 CPU (Coppermine) information, including Slot 1 pinout]
*[http://www.atmarkit.co.jp/fpc/slotsocket/images/slot1_l.jpg An image of a motherboard with Slot 1 connector]

{{Intelsock}}

[[Category:Intel CPU sockets]]