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Smartport drive information & why some 5.25" drives don't work.
The reason only certain drives work with the ROM 03 IIgs, //c+ or Macintosh LC //e
emulator card is because around the introduction of the Apple //c+, Apple changed
the Smartport protocol to where each device hooked to it, (be it 5.25" drive, 3.5"
drive or a Smartport compatible hard disk) needs an ID Byte. The Apple Disk ][,
UniDisk 5.25", DuoDisk and most if not all 3rd party drives DO NOT CONTAIN this
needed ID Byte., Thus rendering such drives unusable with the newer Smartport
protocol.
Explanation: The newer computers 'ask' each device on the drive port what it is, and
the newer 5.25" drive sense this and give back it's ID. The older drives don't know
and the computer wont see them. Even though it will appear to be booting, nothing
will read.
Related Information
The term daisy chain is where each device in a system plugs into the previous
device, thus eliminating the need for additional interfaces. Each device contains a
connector to plug the next one in. On the back of the Apple UniDisk 5.25",
AppleDisk 5.25", Apple UniDisk 5.25" and the AppleDisk 3.5" is a DB-19 Connector
identical to the one that the drive is plugged into. In a drive chain on an Apple II
Computer, ANY 3.5" device(s) must always come before any 5.25" device(s)
Other things that use daisy chaining on the Apple are SCSI hard disks and
AppleTalk (LocalTalk) networking and Ethernet networking. Although Ethernet
and AppleTalk to don't quite 'look' the same, it's still a daisy chain system.
1)A Modification may be necessary for the DuoDisk to work on a IIgs
2)As noted, certain //c+ units seem to work with any version of the 19 Pin 5.25 drive, and do not require
the 'platinum drive'
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