Description: Apple II High-Speed SCSI Card: Setting DMA (11/96)
Header: Apple II High-Speed SCSI Card: Setting DMA (11/96)

 Article Created: 18 January 1995
 Article Reviewed/Updated: 15 November 1996

 TOPIC -----------------------------------------------------------

 This article discusses how to change the Apple II High-Speed SCSI Card's PDMA
 (pseudo direct memory address) switch settings.

 DISCUSSION ------------------------------------------------------

 The computer's SCSI ID number is determined by the positions of switches 2,
 3, and 4 on the SCSI card. See the article "Apple II High-Speed SCSI Card:
 Setting SCSI ID."

 Switch 1 turns DMA on or off.

 DMA is a feature that allows the SCSI card to read or write information
 directly to a storage device (such as a hard disk drive) without having to
 depend on the computer's microprocessor to manage the operation.

 The Apple II High-Speed SCSI Card comes with the DMA switch already in the
 closed (on) position. However, if you have another card (such as an
 accelerator card) that uses its own DMA, you may need to turn off the SCSI
 card's DMA. Follow these instructions to turn DMA off:

 1. Switch the computer off, but leave the power cord plugged in.
 2. Locate Switch 1 on the SCSI card and carefully move Switch 1 to the
   open (off) position.
 3. Refer to the information in the article entitled "Apple II High-Speed
   SCSI Card: Setting SCSI ID" if you want to set the rest of the switches.
 4. Be sure to follow the installation instructions in the Apple II High-Speed
   SCSI Card Owners Guide to install the SCSI card.


 Article Change History:
 15 Nov 1996 - Reviewed for technical accuracy, revised formatting.
 Copyright 1995-96, Apple Computer, Inc.
 Keywords:  hts