Differences between Disk II models?

4 replies [Last post]
Offline
Joined: Dec 19 2003
Posts: 10

Can anyone enlighten me on the internal differences between the older Disk II's (rainbow cable) and the newer ones (grey cable)?

The mechanisms sound different when in operation... and I've found, over the years, that the older ones seem to be both more reliable and better at extracting data from flaky disks.

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.
Simon27's picture
Offline
Joined: Jul 7 2005
Posts: 73
Re: Differences between Disk II models?

I think that the earlier drives were genuine Shugart ones before Apple got the Japanese company Alps to build clones. I'm not sure if this coincided with the change of cable. The grey cables have shielding to reduce the interference caused by ribbon cables.

__________________

'As the name implies, an ombudsman is what you get when you combine words from the diverse fields of meditation, beer, and something called "sman"' -- Scott Adams, Dilbert Creator

Dog Cow's picture
Offline
Joined: Dec 11 2008
Posts: 461
Re: Differences between Disk II models?

The original Disk II drive was a Shugart Associates Model Number 390 as stamped on the bottom of the mechanism. The 390, made especially for Apple Computer, is actually a stripped-down Model 400 missing the track zero sensor, index hole sensor, analog board, and a few other components.

__________________

Email me: dog_cow@m acgui.com
Mac GUI Vault: http://macgui.com/vault/
Apple II Book: http://macgui.com/newa2guide/
Inside Allerton Park book

Offline
Joined: Jun 5 2008
Posts: 380
Re: Differences between Disk II models?

One relatively little known difference. Very early Disk ][ models shipped during DOS 3.1 era used a different resistor value that controls read operations on the analog board. I have one of these and I've had difficultly reading copy protected atarisoft disks with this drive.

Dog Cow's picture
Offline
Joined: Dec 11 2008
Posts: 461
Re: Differences between Disk II models?

Mike WIllegal wrote:

One relatively little known difference. Very early Disk ][ models shipped during DOS 3.1 era used a different resistor value that controls read operations on the analog board. I have one of these and I've had difficultly reading copy protected atarisoft disks with this drive.

What's the serial number on that drive? I have a fairly old Disk II (you can see pictures of it in my book, The New Apple II User's Guide, Appendix G) with a low-serial number and it is an original Shugart model.

__________________

Email me: dog_cow@m acgui.com
Mac GUI Vault: http://macgui.com/vault/
Apple II Book: http://macgui.com/newa2guide/
Inside Allerton Park book