Browse Prior Art Database

Direct Memory Access Compatibility by Use of a DMA Pre-Processor And Post-Processor

IP.com Disclosure Number: IPCOM000101597D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 73K

Publishing Venue

IBM

Related People

Eng, RC: AUTHOR [+2]

Abstract

This article describes a method for direct memory access (DMA) facilities on a new computer system architecture being compatible with an existing architecture via use of a DMA pre-processor and DMA post- processor.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 58% of the total text.

Direct Memory Access Compatibility by Use of a DMA Pre-Processor And Post-Processor

       This article describes a method for direct memory access
(DMA) facilities on a new computer system architecture being
compatible with an existing architecture via use of a DMA
pre-processor and DMA post- processor.

      When building a computer system based on a new hardware
architecture, it is desirable to design the hardware so that software
of an existing architecture can execute on the new system without any
changes (software compatibility).  DMA is one area in which it is
desirable to run existing software on new hardware.  DMA is basically
a process where data is moved between input/output (I/O) devices and
system memory without the intervention of the main processor.
Generally, a separate DMA controller is used to create the system bus
cycles to move the data with the main processor only required to set
up the DMA controller.  The method disclosed herein uses the DMA
controller of an existing computer system architecture, and with the
addition of a DMA pre-processor and DMA post-processor, changes the
DMA controller to match the specification of a new system
architecture.

      Referring to the figure, the DMA control hardware for the new
system architecture consists of a DMA pre-processor, the DMA
controller of the existing system, and a DMA post-processor.

      The DMA pre-processor receives requests for DMA based on the
new architecture protocol from...