Description: Apple II High-Speed SCSI Card: Description (2/97)
Header: Apple II High-Speed SCSI Card: Description (2/97)

 Article Created: 03 April 90
 Article Reviewed/Updated: 28 Feb 1997

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

 This article describes the Apple II High Speed SCSI Card.

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

 The new Apple II High-Speed SCSI Card provides faster data transfer primarily
 because of a new feature called "direct memory access" (DMA) data transfer.
 Data is transferred directly between the computer's memory and the SCSI
 peripheral, with minimal interaction from the computer's microprocessor. The
 result is improved, data-transfer performance. With the new high-speed card,
 data transfers at a rate of up to 1MB per second on the Apple IIGS computer,
 and up to .5MB per second on the Apple IIe computer. In addition to DMA, the
 SCSI manager and firmware have been improved and also contribute to the
 increased performance.

 Compatible with all SCSI peripherals, the Apple II High-Speed SCSI Card
 requires only that device-specific applications and drivers be installed on
 the system. The card ships with drivers and applications for hard disk and CD-
 ROM drives, so that users can take advantage of these devices immediately.
 Device drivers for the tape backup drive and scanner will be made available
 to developers. Users will be able to take advantage of these devices as
 applications are developed. In addition, the new card enables users to
 connect as many as seven SCSI peripherals to their computer.

 Another feature of the card is an on-board terminator, which simplifies setup
 when connecting SCSI peripherals to the computer. Previously, the Apple II
 SCSI Card required users to understand rules regarding placement and quantity
 of terminators between SCSI devices. With the new card, you place one
 terminator at the end of the chain of SCSI devices.

 The Apple II High-Speed SCSI Card also includes improved, hard-disk
 utilities. These utilities make it easy to handle hard-disk management tasks,
 like data backup, disk partitioning and disk verification. The partition and
 verify utilities take advantage of the improved firmware commands for hard
 disk drives. The backup utility can now handle the resource forks that are
 part of the IIGS files. Because these are ProDOS utilities, they can be used
 by both Apple IIe and Apple IIGS users.

 As far as system requirements, the Apple II High-Speed SCSI Card works on an
 Apple IIGS computer or an Apple IIe computer with a 65C02 microprocessor. The
 Apple IIGS requires a 3.5-inch disk drive, while the Apple IIe requires
 either a 5.25- or a 3.5-inch disk drive. Both require a device with a SCSI
 port, appropriate SCSI cabling and one SCSI terminator.


 Article Change History:
 28 Feb 1997 - Reviewed for technical accuracy, revised formatting.
 Copyright 1990-97 Apple Computer, Inc.
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