[Coco] Re: double disk drive

[sroussea at comlab.com]

Thank you very much Mr. Emery,

I will try it very soon.

Sylvain

On 5 Feb 2005, at 6:07, Robert Emery wrote:


> 

> > Yes, I want a switch to use either drive as drive 0 at any time.

> > 

> > I try Crystal City on drive 1 yesterday but it don't works. 

> > Crystal City works only on drive 0 (I think).

> > 

> > I see on the Bob's web page that it's possible to add a switch

> > to do this but I don't see how to do it.

> > 

> > May be Bob can help me?

> 

> So many messages... so little time...  :-)

> The way I did it was to intercept the two drive select lines for D0 and D1

> between the controller and the drives. These are pins 10 and 12 respectively.

> The red wire is number 1.

> 

> Carefully cut between wires to separate a couple of inches of these two wires

> (10 and 12). Now cut them and connect the controller-side of the wires to the

> two common poles of a DPDT switch. Now connect the drive-side of the wires to

> one pair of terminals on the switch, so that in one position the two lines go

> straight through. Next criss-cross the drive-side wires and connect to the

> other pair of switch terminals, so that when you toggle the switch, the Drive

> Select lines are swapped. That's all there is to it.

> 

> I did this specifically so I could boot from either 5.25" drive or 3.5" drive.

> Also incredibly useful is intercepting the Side-Select line (Pin 32) and run it

> to an inverter. Connect the inverted signal to N.O. and non-inverted signal to

> N.C. terminals of an SPDT toggle switch and then connect the common switch

> terminal to the drives (Pin 32). You CANNOT read the back of a FLIPPY by

> toggling the Side-select... you have to copy it over to DS FLOPPY before you

> can do that.

> 

> With the above two switches you can access (and boot from) either side of

> either floppy drive regardless of DOS, regardless of controller.

> 

> With regards to Color FOG requiring an FD502 controller, no it does not. It

> requires DECB 1.1 or HDB-DOS, which also requires DECB 1.1 as its foundation.

> ANY controller should work as long as it has the correct ROM version.

> 

> The DISK Basic ROM came in two versions AFAIK. 1.0 and 1.1. Even though the

> CoCo3 states Disk Extended Color Basic 1.2 (or whatever), this is not telling

> you the DISK ROM version. There are four different roms in the floppy equipped

> CoCo3... Color Basic, Extended Color Basic, Super Extended Color Basic and the

> Disk rom itself. Download Color FOG and run the installer, it will tell you if

> you have DECB 1.1 or not.

> 

> Good luck,

> Bob Emery

> 

> 

> 		

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