Not quite, most mini-PCIe form factor wifi / 3G cards I’ve seen are actually work only over the USB 2.0 lines. There are some PCIe connectors that don’t even do PCI, for example the VAB-600. The first is fairly obvious—your computer needs to have enough physical space to support the length of the card you want to use. The second variable—how the card is keyed—just means the card connector must match the slot you’ll be plugging it into. M.2 Length This motherboard supports M.2 cards in 42mm, 60mm, and 80mm lengths.
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| Enhanced Industry Standard Architecture | |
| Year created | 1988; 32 years ago |
|---|---|
| Created by | Gang of Nine |
| Superseded by | PCI (1993) |
| Width in bits | 32 |
| No. of devices | 1 per slot |
| Speed | 8.33 MHz Half-duplex 33 MB/s[1] |
| Style | Parallel |
| Hotplugging interface | No |
| External interface | No |
The Extended Industry Standard Architecture (in practice almost always shortened to EISA and frequently pronounced 'eee-suh') is a bus standard for IBM PC compatiblecomputers. It was announced in September 1988 by a consortium of PC clone vendors (the Gang of Nine) as a counter to IBM's use of its proprietaryMicro Channel architecture (MCA) in its PS/2 series.[2]
In comparison with the AT bus, which the Gang of Nine retroactively renamed to the ISA bus to avoid infringing IBM's trademark on its PC/AT computer, EISA is extended to 32 bits and allows more than one CPU to share the bus. The bus mastering support is also enhanced to provide access to 4 GB of memory. Unlike MCA, EISA can accept older XT and ISA boards — the lines and slots for EISA are a superset of ISA.
EISA was much favoured by manufacturers due to the proprietary nature of MCA, and even IBM produced some machines supporting it. It was somewhat expensive to implement (though not as much as MCA), so it never became particularly popular in desktop PCs. However, it was reasonably successful in the server market,[3] as it was better suited to bandwidth-intensive tasks (such as disk access and networking). Most EISA cards produced were either SCSI or network cards. EISA was also available on some non-IBM-compatible machines such as the AlphaServer, HP 9000-D, SGI Indigo2 and MIPS Magnum.
By the time there was a strong market need for a bus of these speeds and capabilities for desktop computers, the VESA Local Bus and later PCI filled this niche, and EISA vanished into obscurity.
History[edit]
The original IBM PC included five 8-bit slots, running at the system clock speed of 4.77 MHz. The PC/AT, introduced in 1984, had three 8-bit slots and five 16-bit slots, all running at the system clock speed of 6 MHz in the earlier models and 8 MHz in the last version of the computer. The 16-bit slots were a superset of the 8-bit configuration, so most 8-bit cards were able to plug into a 16-bit slot (some cards used a 'skirt' design that physically interfered with the extended portion of the slot) and continue to run in 8-bit mode. One of the key reasons for the success of the IBM PC (and the PC clones that followed it) was the active ecosystem of third-party expansion cards available for the machines. IBM was restricted from patenting the bus and widely published the bus specifications.
As the PC-clone industry continued to build momentum in the mid- to late-1980s, several problems with the bus began to be apparent. First, because the 'AT slot' (as it was known at the time) was not managed by any central standards group, there was nothing to prevent a manufacturer from 'pushing' the standard. One of the most common issues was that as PC clones became more common, PC manufacturers began increasing the processor speed to maintain a competitive advantage. Unfortunately, because the ISA bus was originally locked to the processor clock, this meant that some 286 machines had ISA buses that ran at 10, 12, or even 16 MHz. In fact, the first system to clock the ISA bus at 8 MHz was the turbo 8088 clones that clocked the processors at 8 MHz. This caused many issues with incompatibility, where a true IBM-compatible third-party card (designed for an 8 MHz or 4.77 MHz bus) might not work in a higher-speed system (or even worse, would work unreliably). Most PC makers eventually decoupled the slot clock from the system clock, but there was still no standards body to 'police' the industry.
As companies like Dell modified the AT bus design,[4] the architecture was so well entrenched that no single clone manufacturer had the leverage to create a standardized alternative, and there was no compelling reason for them to cooperate on a new standard. Because of this, when the first 386-based system (the Compaq Deskpro 386) hit the market in 1986, it still supported 16-bit slots. Other 386 PCs followed suit, and the AT (later ISA) bus remained a part of most systems even into the late 1990s.
Meanwhile, IBM began to worry that it was losing control of the industry it had created. In 1987, IBM released the PS/2 line of computers, which included the MCA bus. MCA included numerous enhancements over the 16-bit AT bus, including bus mastering, burst mode, software-configurable resources, and 32-bit capabilities. However, in an effort to reassert its dominant role, IBM patented the bus and placed stringent licensing and royalty policies on its use. A few manufacturers did produce licensed MCA machines (most notably, NCR), but overall the industry balked at IBM's restrictions.
Steve Gibson proposed that clone makers adopt NuBus.[5] Instead, a group (the 'Gang of Nine'), led by Compaq, created a new bus, which was named the Extended (or Enhanced) Industry Standard Architecture, or 'EISA' (and the 16-bit bus became known as Industry Standard Architecture, or 'ISA').[6] This provided virtually all of the technical advantages of MCA, while remaining compatible with existing 8-bit and 16-bit cards, and (most enticing to system and card makers) minimal licensing cost.
The EISA bus slot is a two-level staggered pin system, with the upper part of the slot corresponding to the standard ISA bus pin layout. The additional features of the EISA bus are implemented on the lower part of the slot connector, using thin traces inserted into the insulating gap of the upper / ISA card card edge connector. Additionally, the lower part of the bus has five keying notches, so an ISA card with unusually long traces cannot accidentally extend down into the lower part of the slot.
Intel introduced their first EISA chipset (and also their first chipset in the modern sense of the word) as the 82350 in September 1989.[7][8] Intel introduced a lower-cost variant as the 82350DT, announced in April 1991; it began shipping in June of that year.[9]
The first EISA computer announced was the HP Vectra 486 in October 1989.[10] The first EISA computers to hit the market were the Compaq Deskpro 486 and the SystemPro.[citation needed] The SystemPro, being one of the first PC-style systems designed as a network server, was built from the ground up to take full advantage of the EISA bus. It included such features as multiprocessing, hardware RAID, and bus-mastering network cards.
One of the benefits to come out of the EISA standard was a final codification of the standard to which ISA slots and cards should be held (in particular, clock speed was fixed at an industry standard of 8.33 MHz). Thus, even systems that didn't use the EISA bus gained the advantage of having the ISA standardized, which contributed to its longevity.
The 'Gang of Nine'[edit]
The Gang of Nine was the informal name given to the consortium of personal computer manufacturing companies that together created the EISA bus. Rival members generally acknowledged Compaq's leadership, with one stating in 1989 that within the Gang of Nine 'when you have 10 people sit down before a table to write a letter to the president, someone has to write the letter. Compaq is sitting down at the typewriter'.[6] The members were:[2]
Technical data[edit]
| bus width | 32 bits |
| compatible with | 8-bit ISA, 16-bit ISA, 32-bit EISA |
| pins | 98 + 100 inlay |
| Vcc | +5 V, −5 V, +12 V, −12 V |
| clock | 8.33 MHz |
| theoretical data rate (32-bit) | about 33 MB/s (8.33 MHz × 4 bytes) |
| usable data rate (32-bit) | about 20 MB/s |
Although the MCA bus had a slight performance advantage over EISA (bus speed of 10 MHz, compared to 8.33 MHz), EISA contained almost all of the technological benefits that MCA boasted, including bus mastering, burst mode, software-configurable resources, and 32-bit data/address buses. These brought EISA nearly to par with MCA from a performance standpoint, and EISA easily defeated MCA in industry support.
EISA replaced the tedious jumper configuration common with ISA cards with software-based configuration. Every EISA system shipped with an EISA configuration utility; this was usually a slightly customized version of the standard utilities written by the EISA chipset makers. The user would boot into this utility, either from floppy disk or on a dedicated hard-drive partition. The utility software would detect all EISA cards in the system and could configure any hardware resources (interrupts, memory ports, etc.) on any EISA card (each EISA card would include a disk with information that described the available options on the card) or on the EISA system motherboard. The user could also enter information about ISA cards in the system, allowing the utility to automatically reconfigure EISA cards to avoid resource conflicts.
Similarly, Windows 95, with its Plug-and-Play capability, was not able to change the configuration of EISA cards, but it could detect the cards, read their configuration, and reconfigure Plug-and-Play hardware to avoid resource conflicts. Windows 95 would also automatically attempt to install appropriate drivers for detected EISA cards.
Industry acceptance[edit]
EISA's success was far from guaranteed. Many manufacturers, including those in the 'Gang of Nine', researched the possibility of using MCA. For example, Compaq actually produced prototype DeskPro systems using the bus. However, these were never put into production, and when it was clear that MCA had lost, Compaq allowed its MCA license to expire (the license actually cost relatively little; the primary costs associated with MCA, and at which the industry revolted, were royalties to be paid per system shipped).
On the other hand, when it became clear to IBM that Micro Channel was dying, IBM licensed EISA for use in a few server systems.
See also[edit]
- Industry Standard Architecture (ISA)
- Micro Channel architecture (MCA)
- VESA Local Bus (VESA)
- Peripheral Component Interconnect (PCI)
- Accelerated Graphics Port (AGP)
- PCI Express (PCIe)
- Low Pin Count (LPC)
References[edit]
- ^Mueller, Scott (2003). Upgrading and Repairing PCS. Que Publishing. p. 310. ISBN9780789729743.
ISA bus speed.
- ^ abCompaq Leads 'Gang of Nine' In Offering Alternative to MCA, InfoWorld, Sep 19, 1988.
- ^Sean K. Daily (1998). Optimizing Windows NT. Wiley. p. 137. ISBN978-0-7645-3110-1.
EISA is still found on many of today's modern servers[,] owing to its long-standing presence in the PC server market.
- ^Lewis, Peter H. (1988-04-24). 'Introducing the First PS/2 Clones'. The New York Times. Retrieved 6 January 2015.
- ^Lemmons, Phil (August 1987). 'Editorial'. BYTE. p. 6. Retrieved 6 November 2013.
- ^ abLaPlante, Alice; Furger, Roberta (1989-01-23). 'Compaq Vying To Become the IBM of the '90s'. InfoWorld. pp. 1, 8. Retrieved 17 March 2016.
- ^Scott M. Mueller (2011). Upgrading and Repairing PCs (20th ed.). Que Publishing. p. 24. ISBN978-0-13-268218-3.
- ^Ziff Davis, Inc. (26 September 1989). 'First EISA chips delivered'. PC Magazine: The Independent Guide to IBM-Standard Personal Computing. PC Magazine: 65. ISSN0888-8507.
- ^Louise Fickel (29 April 1991). 'Intel Debuts EISA Chip Set for Lower Cost 32-Bit Systems'. InfoWorld : The Newspaper for the Microcomputing Community. InfoWorld: 27. ISSN0199-6649.
- ^https://www.nytimes.com/1989/10/22/business/the-executive-computer-the-race-to-market-a-486-machine.html
External links[edit]
To protect yourself and the equipment, follow the precautions in Chapter 2, Safety Precautions and Tools Requirements.
For your protection, also observe the following safety precautions when setting up your equipment:
Follow all cautions, warnings, and instructions marked on the equipment.
Never push objects of any kind through openings in the equipment as they may touch dangerous voltage points or short out components that could result in fire or electric shock.
Refer servicing of equipment to qualified personnel.
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Caution -The chassis AC power cord must remain connected to ensure a proper ground.
Caution -The clock+ board and its modules have surface-mount components that can be broken by flexing the board.
To minimize the amount of board flexing, observe the following precautions:
Hold the board only by the edges near the middle of the board, where the board stiffener is located. Do not hold the board only at the ends.
When removing the board from an antistatic bag, keep the board vertical until you lay it on the Sun ESD mat.
Do not place the board on a hard surface. Use a cushioned antistatic mat. The board connectors and components have very thin pins that bend easily.
Do not use an oscilloscope probe on the components. The soldered pins are easily damaged or shorted by the probe point.
Transport the board in an antistatic bag.
Be careful not to drag boards across surfaces as board components are easily damaged.
There is one clock+ board to a system. The clock+ board provides:
Programmable system and processor clock
Serial, keyboard, and mouse ports for the console
Centralized Time-of-day (TOD) chip that includes NVRAM
Centralized reset logic
Status and control of power supplies
The clock+ board consists of the following subsystems:
Console Bus
Clocks
Reset logic
JTAG
Centerplane connector signals
Figure 6-1 depicts a block diagram of the subsystems and centerplane connector.
Figure 6-1 Clock+ Board Block Diagram
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ConsoleBus
The ConsoleBus provides system boards access to global system control and status as well as to the keyboard, mouse, and serial ports. In addition, there is a NVRAM/TOD chip that maintains the date and time and 8 Kbytes worth of data when the power to the system is shut off.
The state of physical hardware conditions is maintained in registers on the clock+ board. Each of these registers has inputs generated from other subsystems on the clock+ board, from other boards, or from the power supplies in the system. Some clock+ board registers are reserved for controlling various states of the machine.
The ConsoleBus also provides a serial port interface and a keyboard/mouse interface. The primary purpose of the serial port interface is to provide POST messages during power-on. The serial port can be used as a console for systems without a keyboard and display, and for standard serial peripheral hook-ups such as modems and printers.
Clocks
The clock subsystem generates the clocks for the entire system. The base clock is synthesized, then divided into various frequencies. The base clocks are then 'fanned-out' and driven to the centerplane by an array of driver chips. Two processor clocks and one system clock go to each board slot on the centerplane.
Reset logic
The reset logic consists of four subcircuits for controlling the system reset and error state:
Manual reset
System reset
XIR
System error
Removing a Clock+ Board
The clock+ board slot (Figure 6-2) is located near the top of the system, immediately below the peripheral power supply. The illustration shows an Enterprise 4500 server, but the location is similar for the Enterprise 5500 and 6500 servers.
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Caution -The clock+ board is not hot-pluggable. Do not remove the clock+ board until the system has been halted and powered off.
Caution -To avoid damaging internal circuits, do not disconnect or connect any cable while power is applied to the system.
Figure 6-2 Clock+ Board
You must halt the operating system before turning off the system power. See Chapter 11, Powering Off and On for this procedure.
Unfasten cable connectors from the clock+ board front panel and set them aside.
Label cables as you disconnect them, to help identify them for reconnection later.
Loosen the two captive screws securing the board to the system chassis.
Pull the ends of both extraction levers outward simultaneously to release the board from the centerplane receptacles (Figure 6-2).
If you are replacing the clock+ board, remove the TOD NVRAM from the old board and place it on the new board.
This is necessary to match the host ID with the Ethernet ID.
Note -If a entire system is replaced, the TOD NVRAM on the clock+ board must also be changed to maintain the same host ID.
Installing a Clock+ Board
Note -If you are replacing the clock+ board, then the TOD NVRAM from the old board must be removed and placed on the new board. Note also that if a system is replaced, then the TOD NVRAM on the clock+ board must also be changed.
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Carefully insert the board in the proper slot in the card cage, ensuring that the board does not slip out of the left and right card guides.
The component side of the board must face up.
Ensure that both extraction levers are in the outward position as you slide the board toward the backplane connectors (Figure 6-2).
The board will not seat fully unless the levers are in this starting position.
Caution -DO NOT FORCE any board into a slot; this can cause damage to the board and system. The board should insert and seat smoothly. If it binds, remove the board and inspect the card cage slot for any obvious obstructions. Also inspect both the board and the backplane for bent pins or other damage.
Use the extraction levers to seat the board.
Simultaneously swing both levers into the locked position. Do not press on board front panel to seat it--doing so will damage the connector pins.
Secure the board to the chassis using the two captive screws, one on each side.
Connect any applicable interface cables to the front panel of the board.
Turn on system power. See Chapter 11, Powering Off and On for this procedure.
Boot the system.