[Coco] DW4 error

[Gene Heskett]

On Thursday 03 July 2014 13:20:28 Richard E Crislip did opine
And Gene did reply:
> On Tue, 1 Jul 2014 15:00:03 -0400
> 
> Gene Heskett <gheskett at wdtv.com> wrote:
> > On Tuesday 01 July 2014 12:38:11 Kandur did opine
> > 
> > And Gene did reply:
> > > True, but 115 kbps how many baud?
> > 
> > Its a direct value, kilo(thousand) baud per second.
> > 
> > Actually I believe 115,200 baud specifies it more precisely, as would
> > 115.2kbps.
> > 
> > Also, this really does belong on the list for future reference.
> > 
> > Cheers, Gene Heskett
> 
> Hi Gene,
> 
> This raises an age old question, for me at least 8-), what the hell is
> a BAUD? What does it measure and how does it relate to Kbs? TIA

A BAUD is a single bit time in what would be, for 8 bit ascii data, a 10 
bit per byte transmission, because there is an added start bit of known 
polarity for synch purposes, and an ending stop bit of known polarity. So 
a 9600 baud circuit, running without any flow controls, will actually 
transmit 960 8 bit characters a second.

The bit time for a 9600 baud circuit then is 
1/9600=0.00010416666666666666667 seconds per baud or bit.

A zmodem send to the coco3 needs to be held to an average below about 625 
cps else it overruns the per byte processing loop in rz. When sending from 
here to the coco, I have this linux zmodem set for a 256 byte window, 
which requires a handshake ack from the coco3 before the next packets 
transmission can begin.  This is enough to slow it to around 640 cps and 
there are not any overrun errors to deal with then.

I often use that math when dealing with the bit banger as the Nitros9 std 
setting actually gives around 11,800 baud on my 6309 equipt machine.  It 
takes a setting somewhere in the 29 to 30 area to get 9600, and the 
default seems to be 13, much too fast on a 6309.  Off more than 150 baud 
from 9600, and these ser-usb gismo's slobber all over themselves without 
actually sending any data on.

Cheers, Gene Heskett
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