28 Jan
2014
28 Jan
'14
7:53 a.m.
On Jan 28, 2014, at 2:24 AM, Chuck Guzis <cclist at sydex.com> wrote:
On 01/27/2014 09:24 PM, Mouse wrote:
Yes. There are a few modern micros that have this as an autobaud
option, actually, and they usually expect a CR or three to get
the speed right. It's sort of more handy than having a fixed
console rate, unless you forget and type a few characters at the
beginning of a session and screw up the baud rate until reset.
- Dave
Indeed. Consider a wire which is in the marking
state, then goes to
the spacing state for 312.5 microseconds, returning to mark and staying
there for, say, several milliseconds. (I _think_ I'm using `mark' and
`space' correctly here; they might need switching. By `mark' I mean
the idle state and `space' the other state.) Is that a start bit and
two spacing data bits at 9600 baud (with the rest of the character
being mark bits) or is it a start bit and five spacing data bits (plus
ditto) at 19200 baud? Or is it a framing error at 38400 baud? Or
perhaps just a start bit, with all the data being mark bits, at 3200
baud? Or an entire (8-bit) character of spacing bits at 28800 baud?
Answer: without more information than just the signal on the wire,
there is absolutely no way to tell.
So, is that why one had to hit CR a few times on the old dialup BBS to get it to
determine your modem speed? Because it was impossible?