Chapter 1: EISA Overview
up. System resources such as serial ports, parallel ports, VGA and other manu- facturer-specific functions can be fully configured programmatically.
The EISA expansion card manufacturer includes a configuration file with each expansion card shipped. The configuration files can be included with either new, fully-programmable EISA boards or switch-configured ISA or EISA products. The configuration files are used at system configuration time to automatically assign global system resources (such as DMA channels and interrupt levels), thus preventing resource conflicts between the installed expansion cards. For switch-configurable boards, the configuration files can be used to determine the proper assignment of resources and to instruct the user about the proper selection of switch settings.
To accomplish the automatic configuration of the system board and expansion cards, EISA uses slot-specific I/O port ranges. An EISA card using these ranges can be installed into any slot in the system without the risk of I/O range conflicts. These I/O ranges can be used for expansion card initialization or for normal I/O port assignments that are guaranteed not to conflict with any other expansion board installed in the system.
EISA also includes a product identification mechanism for system boards and EISA expansion cards. The product identifier allows products to be identified during the configuration and initialization sequences for the system and EISA expansion boards. EISA includes guidelines for selection of a product identifier. The identifier for each product is selected by the product manufacturer and does not need the approval of any other party in the industry. However, a manufacturer-specific ID is assigned to each vendor by BCPR Services, the firm that manages the EISA specification.
EISA Feature/Benefit Summary
Table 1-1 provides a summary of the key features and benefits of the Extended Industry Standard Architecture.
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EISA System Architecture
Table 1-1. EISA Feature/Benefit Summary
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Feature |
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Benefit |
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Backward compatible with all ISA |
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Customer base retains value of installed ISA |
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expansion boards |
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cards. |
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Board size |
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63 square inches of board space permits imple- |
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mentation of powerful, highly-integrated ex- |
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pansion cards. |
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+5Vdc at approximately 4.5A |
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Ample power for expansion cards employing a |
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available at each expansion slot |
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large amount of highly-integrated logic. |
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32-bit address and data buses |
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Support for 4GB of memory and 32-bit transfers. |
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Programmable levelor edge- |
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Interrupt request lines may be shared by multi- |
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triggered interrupt recognition |
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ple devices. |
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Enhanced DMA capabilities |
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Both ISA and EISA DMA devices have access to |
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memory above 16MB. New bus cycle types and |
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32-bit data bus allow faster transfer speeds |
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(rates of up to 33 MB/second). |
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Bus Master Support |
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Support for up to fifteen bus master expansion |
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cards, fast burst bus transfers, automatic data |
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bus steering and control line translation. |
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Automatic system configuration |
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Supports automatic configuration of the EISA |
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system board and EISA expansion cards each |
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time the system is powered up. Also provides |
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help to the end user in configuring older ISA |
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expansion cards. |
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