Browse Prior Art Database

DMA Transfer between Two Adapters on a Graphic Bus

IP.com Disclosure Number: IPCOM000112814D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Arimilli, LB: AUTHOR [+3]

Abstract

Disclosed is a method for DMA transfer between two adapters on a Graphics bus in which the bus protocol allows only for data transfer between the I/O controller and a Graphics adapter.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

DMA Transfer between Two Adapters on a Graphic Bus

      Disclosed is a method for DMA transfer between two adapters on
a Graphics bus in which the bus protocol allows only for data
transfer between the I/O controller and a Graphics adapter.

      An Address Configuration Register is added to the I/O
controller and this register is initialized by software during the
IPL sequence.  The I/O controller uses the address in this register
to compare with the DMA address presented by a Graphics adapter on
the Graphics bus.  If the DMA address on the Graphics Bus is greater
than the address in the I/O controller's register, then the I/O
controller ignores the DMA transfer thereby allowing another Graphics
adapter on the Graphics bus to respond to the DMA transfer.

      This method allows adapter-to-adapter data transfer without
violating the existing bus protocol.