[Coco] PIA setup

[Roger Taylor]

At 10:38 AM 12/30/2008, you wrote:

>On 12/29/08, Roger Taylor wrote:

> >

> > <snip>

> >

> > Another thing I noticed.  When you turn a CoCo on, it "transmits" a

> > phantom character to the remote PC due to how BASIC sets up the PIA

> > chips.  At some point a start bit is seen by the PC which leads to a

> > byte being framed.  It could be that a break or partial break is

> > transmitted.  I haven't looked further into it.

> >

>

>Upon Reset, all the PIA data lines act as Inputs. The bit-banger

>output will likely go low at that time and the PC will see this as a

>start bit (it could be considered a BREAK if it remains low long

>enough). Color Basic (CoCo 1 and 2) sets the bit banger output to the

>normal MARKing state fairly soon after reset (at address $A04F). The

>CoCo 3 doesn't setup the output until after the initialization code

>has been moved to RAM.

>

>Darren



I wonder if by the $4F'th byte into BASIC if the PC would consider it 
to be a break signal on the line.  Is it 3 character lengths to be 
considered a break, 4, ?  Can't recall the duration, but I'm sure my 
Belkin USB to Serial adaptor has it's own idea of what it should 
be.  I'd like for CoCoNet to have a signal break command telling the 
server it needs to get out of whatever loop it's in and back to the main loop.


-- 
Roger Taylor

http://www.wordofthedayonline.com