Date   : Tue, 23 Aug 1994 12:08:05 +0100
From   : jfid@... (James Fidell)
Subject: Re: Mine did something! Eeek!

James Bonfield wrote:

> I've finally remembered to bring my Adv U.G. in today. I'll have
> another bash at finishing my 6522 code ;-) Has anyone got the
> datasheets for it? Does anyone know the difference between ORA and
> ORA non-handshake? The AUG has a bit about it in section 22.4.2, but
> is pretty wooly. It seems to be implying that non handshake mode has
> does not use the CB2 interrupt flag. Is this only on outputs? Is it
> possible to input by writing to a non-handshake pin on the 6522 that
> doesn't generate a CB2 interrupt? It'd help enormously if the AUG had
> bothered to give the pin out for the chip.

For the system VIA, I wouldn't worry about the two different ORA/IRA
registers.  I'm fairly sure that the OS only uses the non-handshaking
one, which makes the implementation all that much easier to get off the
ground.

>From what I remember, there is definitely enough information in the AUG
to sort this out fully, but I decided that I didn't need to for the
moment.

James.

-- 
 "Yield to temptation --             |
  it may not pass your way again"    |     jfid@...        
                                     |
        - Lazarus Long               |              James Fidell