[Coco] Question about the PIA RAM Size input

[coco at yourdvd.net]

I did just notice that pb6 of the keyboard pia is called ram size output
whilst the pia pin in question is ram size input and since they are
connected together and pulled high via a 4,7k resistor in the cc3,
might it not be possible to configure pb6 of keyboard pia as an output
during the routine in question and output a low thereby pulling the
ramsize pin low? just a thought -robert 

> -------- Original Message --------
> Subject: Re: [Coco] Question about the PIA RAM Size input
> From: wdg3rd at comcast.net
> Date: Tue, May 01, 2007 9:33 pm
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> 
> Oh, you spoiled my punch line.  I was just going to say "fry it and see".
> 
> Yes, I can be a basty nastard when I drink, especially when I 
> remember I have to go back to the dead end in the morning.  Poorly
> paid as I was, tech support for Radio Shack 25 years ago was a lot
> more fun.
> -- 
> Ward Griffiths    wdg3rd at comcast.net
> 
> The reason folks don't think of installing Windows as a painful
> experience is roughly the same reason men don't think of childbirth as
> a painful experience.      Mike,
> http://www.theregister.co.uk/2007/03/30/letters_3003/
> 
>  -------------- Original message ----------------------
> From: coco at yourdvd.net
> > actually, depending on the coco (1 or 2) you have and the installed
> > memory, depends on how it is jumpered, whether it be to gnd, vcc, pb6
> > of the keyboard pia, etc. I wouldn't do it - say it is jumpered to gnd,
> > and you output a logic 1 to it - or vice versa - probably wouldn't be
> > good. Look over some schematics of various coco models - the jumpering
> > scheme is different on the three coco 1 and 2 model schematics I just
> > glanced at...r
> > 
> > > -------- Original Message --------
> > > Subject: [Coco] Question about the PIA RAM Size input
> > > From: "Darren A." <darccml at hotmail.com>
> > > Date: Mon, April 30, 2007 8:27 am
> > > To: coco at maltedmedia.com
> > > 
> > > Hi all,
> > > 
> > > Does anyone know if any harm can be done by reprogramming the Data
> > > Direction 
> > > Register of PIA 2 such that the RAM Size input becomes an output? 
> Since 
> > > this line is often jumpered to either GND or +5V, what happens when
> > > the PIA 
> > > is trying to drive the line?
> > > 
> > > The RAM Size input is on the 'B' side of the PIA, and the 6821
> datasheet 
> > > says:
> > > 
> > > "As outputs, these lines are compatible with standard TTL and may
> also
> > > be 
> > > used as a source of at least one milliampere to directly drive the
> > > base of a 
> > > transistor switch."
> > > 
> > > Darren
> > > 
> > > _________________________________________________________________
> > > The average US Credit Score is 675. The cost to see yours: $0 by
> > > Experian. 
> > > 
> > http://www.freecreditreport.com/pm/default.aspx?sc=660600&bcd=EMAILFOOTERAVERAGE
> > > 
> > > 
> > > --
> > > Coco mailing list
> > > Coco at maltedmedia.com
> > > http://five.pairlist.net/mailman/listinfo/coco
> > 
> > 
> > --
> > Coco mailing list
> > Coco at maltedmedia.com
> > http://five.pairlist.net/mailman/listinfo/coco
> 
> 
> --
> Coco mailing list
> Coco at maltedmedia.com
> http://five.pairlist.net/mailman/listinfo/coco