Re: IIGS 3.5inch Disk Drive questions...

[Roger Johnstone <rojaws@es.co.nz>]

In <3EF1572E.F0ADC595@usa.net> Jeff Thomas  wrote:

> Roger Johnstone wrote:
> 
>> The IIgs disk drive port can support multiple SmartPort drives (like 
>> the UniDisk 3.5), up to two Apple 3.5 drives and two 5.25" drives in 
>> a daisy chain connection. The rule is that SmartPort drives go first, 
>> then Apple 3.5 drives, and 5.25" drives are connected at the end of 
>> the chain.
> 
> The Apple 3.5 drive (model no. A9M0106) itself is compatible with both 
> the Mac and IIGS, automatically detects which disk format to use when 
> connected to either machine being; ProDOS, Mac 800Kb, but would that 
> made it a SmartPort drive?

No, the Apple 3.5 Drive is a "dumb" drive. Like the 5.25" drives, it is 
controlled directly by the computer it's attached to. For example, to 
read a block of data from the disk the computer needs to work out which 
track the block is on, then it sends signals to turn on the motor, moves 
the read/write head to the right track, and reads the data from the disk 
itself in real time. The SmartPort drives like the UniDisk 3.5 and the 
various hard drives that were available that connected to the disk port, 
are smart in that they have their own processor on board. The computer 
can then send commands like "read block #58" and the drive will find the 
block itself, read it, and then send it to the computer.

David Wilson questioned me on the drive connection order in an email. I 
checked, and I had misremebered (Thanks David!). The Apple 3.5 Drives go 
first, then the SmartPort drives, then the 5.25" drives.

-- 
Roger Johnstone, Invercargill, New Zealand

Apple II - FutureCop:LAPD - iMac Game Wizard
http://homepages.ihug.co.nz/~rojaws/
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My software never has bugs. It just develops random features.