RE: PC as 1541

Wonder if we could embed a proc and flash in a serial din connector and
have a 1541 for the size of a DIN

-----Original Message-----
From: owner-cbm-hackers@musoftware.de
[mailto:owner-cbm-hackers@musoftware.de] On Behalf Of Steve Gray
Sent: Thursday, April 28, 2011 3:22 PM
To: cbm-hackers@musoftware.de
Subject: Re: PC as 1541





----- Original Message ----
> From: Spiro Trikaliotis <ml-cbmhackers@trikaliotis.net>
> To: cbm-hackers@musoftware.de
> Sent: Thu, April 28, 2011 3:02:11 PM
> Subject: Re: PC as 1541

> > I am wondering if it's possible to use ATN line then to generate an
> > IRQ on the PC side (so you don't need polling).
>
> Neglecting that the "market" for a parallel port based solution will
> get smaller and smaller:
>
> In principle, this would be possible, yes. Unfortunately, the number
> of parallel port input lines is limited on the PC. Even worse, the
> number of input lines that can generate an IRQ is much more limited:
> You only have one line.
>
> For the listener hold off, we already need the DATA line generate an
> interrupt. We could add the ATN line, so both DATA and ATN generate an
> IRQ. However, then we would need another input line (to distinguish
> ATN and DATA), which we do not have. In fact, the current X*1541
> cables all do not have an ATN input line at all!

Could you not connect both ATN and DATA to the regular IO lines, but also
to the input of an OR GATE, which is then fed  to the interrupt line? The
IRQ triggers and you check the regular IO lines to determine which line
fired,

Steve

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