Chasis & SCSI Ports of a tower Macintosh Model.

chassis and scsi connectivity in older Mac models

Upgrading an older Mac with a new SCSI drive has become confusing to the Macintosh user. The advancement of SCSI Technology in hard disk drive specifications and the current terminology of the disk drive performance specifications all confuse the user when trying to correlate the performance characteristics of a hard disk drive with their Mac computer SCSI specs so they can easily upgrade the SCSI storage of their system.

The illustration shown below explains the SCSI supported on older Macs. A Power Macintosh 9600 chassis is used to illustrate the different features and the way they are implemented so that the process of upgrading storage becomes clear.

Note: Before installing memory or a disk drive in the system; please remove the expansion bay battery, the AC adaptor or any other cables or devices connected to the computer.

Some drive expansion bays allows only one inch high drive; like in this particular chassis, only one inch drives [termed LP or Low Profile in the industry] can be installed in the top expansion bay shown with the drive installed in the expansion in the illustration, space provided in the chassis limits the drive form factor to one inch.
The vacant expansion bay shown alows drives up to 1.6" in height to be installed in the bay.

Built-in SCSI Macs comes with SCSI ribbon cable that is attached to the built in SCSI drive; the ribbon cable has extra socket for connecting additional SCSI drives peripherals....

PCI SCSI cards are used to connect 68-pin drives for faster Xfer Rate compared to built in SCSI drives, internally most SCSI cards provide both 68-pin and 50 Pin connectors. externally 50-pin High density connector or 68-pin Wide connector is provided, some cards supports 68-pin VHDCI connectors, more common in dual channel SCSI cards.

Desktop Macs and Clones support on board Internal 50-pin SCSI ports to connect 50-pin SCSI peripherals.
(Untill Power Mac Beige G3s)
Exteral SCSI ports were present on all the Mac and Mac clones till Power Mac Beige G3s.
Exteral SCSI peripherals can be connected via a 50-pin SCSI Cable.
50-pin cable

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Upgrading an older Mac with a new SCSI drive has become confusing to the Macintosh user. The advancement of SCSI Technology in hard disk drive specifications and the current terminology of the disk drive performance specifications all confuse the user when trying to correlate the performance characteristics of a hard disk drive with their Mac computer SCSI specs so they can easily upgrade the SCSI storage of their system. The illustration shown below explains the SCSI supported on older Macs. A Power Macintosh 9600 chassis is used to illustrate the different features and the way they are implemented so that the process of upgrading storage becomes clear.

	Note: Before installing memory or a disk drive in the system; please remove the expansion bay battery, the AC adaptor or any other cables or devices connected to the computer. Some drive expansion bays allows only one inch high drive; like in this particular chassis, only one inch drives [termed LP or Low Profile in the industry] can be installed in the top expansion bay shown with the drive installed in the expansion in the illustration, space provided in the chassis limits the drive form factor to one inch. The vacant expansion bay shown alows drives up to 1.6" in height to be installed in the bay. Built-in SCSI Macs comes with SCSI ribbon cable that is attached to the built in SCSI drive; the ribbon cable has extra socket for connecting additional SCSI drives peripherals.... PCI SCSI cards are used to connect 68-pin drives for faster Xfer Rate compared to built in SCSI drives, internally most SCSI cards provide both 68-pin and 50 Pin connectors. externally 50-pin High density connector or 68-pin Wide connector is provided, some cards supports 68-pin VHDCI connectors, more common in dual channel SCSI cards.



Desktop Macs and Clones support on board Internal 50-pin SCSI ports to connect 50-pin SCSI peripherals. (Untill Power Mac Beige G3s)	Exteral SCSI ports were present on all the Mac and Mac clones till Power Mac Beige G3s.	Exteral SCSI peripherals can be connected via a 50-pin SCSI Cable.