Re: Drive disconnect switch for SX 64

Oops, thanks for the clarification.

Steve



----- Original Message ----
> From: Spiro Trikaliotis <ml-cbmhackers@trikaliotis.net>
> To: cbm-hackers@musoftware.de
> Sent: Tue, November 30, 2010 3:02:08 PM
> Subject: Re: Drive disconnect switch for SX 64
> 
> Hello Steve,
> 
> * On Tue, Nov 30, 2010 at 09:50:37AM -0800 Steve Gray wrote:
> > changing those will not make the device invisible. You could send a command 
>to 
>
> > make the device say 31 which most software would probably not support.
> 
> Well, device 31 is *surely* not supported by *any* software. This device
> number is reserved and used for UNTALK and UNLISTEN. It is the only
> number that is reserved, everything else (0-30) can be used for IEC bus
> routines (although you have to use the IEC routines directly then,
> because the "normal" routines will shortcut addresses 0-3).
> 
> Now, the 1541/1571 test for the UNLISTEN and UNTALK before they test for
> the LISTEN and TALK address (cf. $E884-$E8A7 in the 154x ROM). Thus,
> setting the device address to 31 effectively disables the drive's
> ability to react on a command on the IEC bus.
> 
> Regards,
> Spiro.
> 
> -- 
> Spiro R. Trikaliotis                              http://opencbm.sf.net/
> http://www.trikaliotis.net/                    http://www.viceteam.org/
> 
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