Browse Prior Art Database

Multiple Interfaces On a Single Adapter Card Using Bus Masters And/Or DMA Devices

IP.com Disclosure Number: IPCOM000119388D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 3 page(s) / 83K

Publishing Venue

IBM

Related People

Bowlds, PA: AUTHOR [+3]

Abstract

This article describes methods of attaching more than one input/output (I/O) device to a single adapter card to permit the attachment of a greater number of I/O devices than the number of available expansion slots.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 60% of the total text.

Multiple Interfaces On a Single Adapter Card Using Bus Masters And/Or
DMA Devices

      This article describes methods of attaching more than one
input/output (I/O) device to a single adapter card to permit the
attachment of a greater number of I/O devices than the number of
available expansion slots.

      The first method is to utilize a bus master as a controller for
dissimilar devices, as shown in Fig. 1. Appropriate buffer management
could provide increased efficiency and bandwidth utilization as a
secondary benefit.

      The second method is similar to the first method except that
the bus master is replaced by a direct memory access (DMA) device.

      The third method is to have multiple bus masters on an adapter
card that could control one or more similar or dissimilar devices
(Fig. 2).  In this method, each bus master would have its own
arbitration level and can request the bus independently of other bus
masters on the same card. Each of these bus masters appears as though
it resides on a discrete adapter card.  Since there are more
arbitration levels available than there are adapter card slots in
most of today's systems, this effectively increases the number of
slots that the system sees.  The programmable option select (POS)
assumes a single default for the adapter card.

      The fourth method is similar to the third method, but it
utilizes DMA devices instead of the bus masters.

      In present implementations, more than one I/...