Serial Port Access

Jerry Jensen jhj at
Wed Aug 15 14:47:59 EDT 2012

Mark and space are the two possible levels of a single bit. Mark corresponds to a logical 1 and in RS-232 is a *negative* voltage. Space is a logical 0, a positive voltage. Parity is an extra bit tacked onto a word as rudimentary error checking. 7 bits even parity uses the extra bit to make the number of ones in the word be even. Likewise, odd parity sets the parity bit to make the number of ones in the word be odd. Most commonly these days is 8 bits, no parity. Note the ASCII is 7 bits, so the 8th bit, which might or might not be a parity bit, is often ignored.

There are a lot of Marks around here. Smart ones too! I'm usually one of the spaces. Think positive!


On Aug 15, 2012, at 11:20 AM, Bob Sneidar wrote:

> Hi all. 
> I noticed Sarah's stack has for parity, "None, Odd, Even". I am dealing with an old phone system that uses "space" but there is also "mark". What is the significance of this, and does parity even matter? I have the stack set to even now, and have had it set to none and I still seem to get the data just fine, but I want to make sure. 
> Bob
> On Aug 10, 2012, at 6:03 PM, stephen barncard wrote:
>> Sarah's serial stack
>> go URL ""
> _______________________________________________
> use-livecode mailing list
> use-livecode at
> Please visit this url to subscribe, unsubscribe and manage your subscription preferences:

More information about the use-livecode mailing list