Archived - Power Macintosh G3, G4: Differences Between Available SCSI Cards
This article lists SCSI cards available for Power Macintosh G3 (Blue and White) and Power Mac G4 computers.
The three Apple SCSI cards available as configure-to-order options are as follows, with a shortened name in parentheses:
- Ultra SCSI PCI Card (Ultra)
- Single Channel Ultra2 LVD SCSI Card (Single)
- Dual Channel Ultra2 LVD SCSI Card (Dual) version 1 and 2
The version 2 dual channel SCSI card is functionally equivalent to the version 1 card, though it has been tested and approved for use with the Power Mac G4 (AGP Graphics) computer. Refer to the table below for specific technical information. The card is based on the ATTO ExpressPCI UL2D card. You may refer to the ATTO Web site at
for more information about the card.
Table 1 differentiates the various Apple cards based on their features. The Ultra card is best used for connecting slower, legacy SCSI-1 and SCSI-2 devices such as tape drives, hard drives, and scanners, as well as Ultra Narrow SCSI devices.
While there is some overlap among the cards, make purchase decisions based on what type of device you intend to connect to the card.
|Supported Computer||Power Macintosh G3 (Blue and White) and Power Mac G4||Power Macintosh G3 (Blue and White)||Power Macintosh G3 (Blue and White)||Power Mac G4 (AGP Graphics)|
|Max. Transfer Rate (MB/Sec)||20||80||80 per channel||80 per channel|
|Apple Supported Types||SCSI-1, SCSI-2 (Fast), Ultra Narrow||Ultra2 LVD||Channel A: SCSI-1, SCSI-2 (Fast), Ultra Narrow, Ultra Wide, Ultra2 LVD
Channel B: Ultra2 LVD
|Channel 1: SCSI-1, SCSI-2 (Fast), Ultra Narrow, Ultra Wide, Ultra2 LVD
Channel 2: Ultra2 LVD
|Internal Connector||50-pin standard (plug) (Not Apple Supported)||68-pin high-density Ultra2 (socket)||Channel A: 68-pin high-density Ultra2 (socket)
Channel B: 68-pin high-density Ultra2 (socket), and 50-pin standard (plug) *
|Channel 2: 68-pin high-density Ultra2 (socket)|
|External Connector||50-pin high-density (socket) Includes a high density 50-pin to DB25 adapter||68-pin high-density Ultra2 (socket)||Channel A: 68-pin high-density Ultra2 (socket) **||Channel 1: 68-pin VHDCI Ultra2 (socket)|
|Max. Devices Int/Ext||Up to 7 total||Up to 15 total||Up to 30 total||Up to 30 total|
|Maximum Cable Length Internal/External||3 m with non-Ultra devices; 1.5 m with Ultra devices or a mix of Ultra and non-Ultra devices||12 m with only Ultra2 LVD devices||Channel A: 3 m with non-Ultra devices; 1.5 m with Ultra devices or a mix of Ultra and non-Ultra devices; 12 m with only Ultra2 LVD devices
Channel B: 12 m with only Ultra2 LVD devices
|Channel 1: 3 m with non-Ultra devices; 1.5 m with Ultra devices or a mix of Ultra and non-Ultra devices; 12 m with only Ultra2 LVD devices
Channel 2: 12 m with only Ultra2 LVD devices
|PCI System Bus||32 bit||32 bit||64 bit||64 bit|
|Driver Compatibility||Compatible with SCSI Manager 4.3, and earlier drivers||Requires SCSI Manager 4.3 compliant driver||Requires SCSI Manager 4.3 compliant driver||Requires SCSI Manager 4.3 compliant driver|
Table 1 Apple SCSI Card Specifications
* For maximum performance, the internal connector (Channel B) is recommended for Ultra2 devices only.
** The internal/external (Channel A) connectors are recommended for use with all SCSI types.
All three Apple SCSI cards allow the Power Macintosh G3 (Blue and White) to start up from an attached device that has appropriate system software installed.
Maximum throughput (Ultra2) is possible only when Ultra2 devices are on the SCSI bus. When you connect a non-Ultra2 device to the single or dual channel card, the SCSI manager negotiates with each device for maximum speed for that particular device.
1. The term Low Voltage Differential (LVD) can be used interchangeably with the term Ultra2.
2. High Voltage Differential devices, also known as Differential devices, are not compatible.
3. With regard to the Ultra2 LVD SCSI cards, there are adapters to connect a Narrow device to the Wide bus, but this may severely affect performance. Using such an adapter is not recommended or supported.
4. Though Apple SCSI cards may be similar to certain Adaptec cards, use only Apple SCSI Card Firmware Updates on Apple cards. Do not use Apple Firmware Updates on Adaptec Power Domain cards. Similar firmware updates for Adaptec SCSI cards may be available from Adaptec.
5. For more information on the Apple Ultra SCSI PCI Card, see About Your Ultra SCSI PCI Card
This article provides information about a non-Apple product. Apple, Inc. is not responsible for its content. Please contact the vendor for additional information.
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