Re: Apple II Interrupt card

[et472@FreeNet.Carleton.CA (Michael Black)]

Rob (rsteinmetz@mindspring.com) writes:
> Bill Garber wrote:
> 
>  >
>  > One of the questions was, does the mouse card provide the INTs
>  > without the mouse.
> 
> Yeah I know I asked it. But I think it was answered that the card
> provides the interrupts.
> 
>  > The INT MGR card does, and what if 50 people want to run Contiki,
>  > there are barely that many mouse cards left, IMHO.
>  >
>  > Bill @ GarberStreet Enterprises http://garberstreet.netfirms.com
>  >
> That's true. I just wonder if it's worth the cost to make a batch of 
> interrupt manager cards, when for a few dollars more you could make 
> something with more capability.
> 
> I have also received an email from another person who thinks a simple 
> mod to the ][ and ][+ could provide the signal necessary.
> 
That makes sense, since it's just two counters, which must be hooked
to the interrupt lines.  The point of the board may be simply to
get the results without having to modify the Apple II board.

The Apple II board itself is full of counters, for generating
all the video timing.  One assumes the interrupt board is being
clocked from one of the higher frequency clocks on the Apple bus,
and the motherboard counters are getting their clock signal from
the same source.  Chances are good that the needed signal is available,
either deliberately (because it's used somewhere) or just as a byproduct of
dividing down various signals.

Since someone mentioned that the interrupt board only makes a few
connections to the bus, it should be very easy for someone who
has one to provide which pins.  One will be ground, one will be
+5V, one will be the interrupt pin, and then the last one has
to be clocking.  It should be really easy from there to figure it
out, without actually having to trace the rest of the circuitry
on the interrupt board.

   Michael