[Coco] Re: CoCo needs?

[jdaggett at gate.net]

Roger

Correct on the side select problem. That is the default issue with the 
1793/1773/2973 chips. These controllers are designed for single 
side drives. The 1795/1797/2795/2797 all will handle double sided 
drives. The 1793/2783 sacrific double sided drives for internal clock 
divide. I have seen designs where the 2797 is used and the clock 
divide circuit is external so that HD format can be used. This will 
allow double sided drives and HD format together. 

With the 2793 some means of external side select will have to 
done. Currently RSDOS treats the second side of a double sided 
drive as another drive. OS9 does a work around with the sacrifice of 
not being able to access four physical drives. 

james 

On 8 Mar 2005 at 23:13, Roger Merchberger wrote:

Date sent:      	Tue, 08 Mar 2005 23:13:07 -0500
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From:           	Roger Merchberger 
<zmerch at 30below.com>
Subject:        	Re: [Coco] Re: CoCo needs?
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> Also, the gray matter is kinda fuzzy here -- but IIRC the standard
> CoCo controllers could handle a maximum of 4 drives, *if SS*. Didn't
> OS-9 "sacrifice" DS3 to enable double-sided functionality, thereby
> allowing a maximum of 3 DS drives? (Please correct me if I'm wrong -
> as I said, it's been a *long* time for some of this! ;-)