Question about modems

[Brent Hilpert]

On 2019-Nov-14, at 9:59 PM, Brent Hilpert via cctalk wrote:

> On 2019-Nov-14, at 9:30 PM, Jim Brain via cctalk wrote:
>> On 11/14/2019 11:05 PM, Brent Hilpert via cctalk wrote:
>>> 
>>> (Without having gone through the code presented in full detail, but thinking from root premises.)
>>> 
>>> ASCII A = 0x41 --> 2 bits on
>>> ASCII T = 0x54 --> 3 bits on
>> 
>> I agree, though I believe aT,At,AT,and at are all allowed, which complicates things a bit aT is the bad one, where the calc for 7E1 and 7S1/8N1 yield the same values...
> 
> ... right, was forgetting about case.
> But if you're trying to account for mixed case, I don't think the CR resolves it anyways:
> 
> ASCII  A = 0x41 --> 2 bits on
> ASCII  T = 0x54 --> 3 bits on
> ASCII  a = 0x61 --> 3 bits on
> ASCII  t = 0x74 --> 4 bits on
> ASCII CR = 0x0D --> 3 bits on
> 
> In sequence "Ta<CR>", all characters have an odd number of bits on and would produce the same parity value, and collectively would be indistinguishable from a corresponding constant M or S parity.

Whoops, that should have been: in sequence "aT<CR>".