[time-nuts] 57600 baud rate with Basic etc

[David]

I design in asynchronous serial for diagnostics all of the time.  It
is easy to galvanically isolate if necessary, is easy to debug, uses
the fewest pins, and is well supported on both ends although if
needed, USB to serial translation always seems to cause more problems
than it solves.

I do not remember now where I saw it but many years ago, I ran across
an RS-232 type of interface where the first edge of the start bit was
used as the high precision timing reference for the following message.
I am not sure of the exact details but as I recall, the UART had some
external glue logic and maybe a synchronous clock so the start bit
edge was aligned to the timing reference to within the inherent jitter
of the glue logic without any clock uncertainty.  The receiver had a
standard UART with a parallel low jitter logic path to watch for the
start bit.

On Wed, 10 Oct 2012 11:49:13 -0400, "Bob Camp" <lists at rtty.us> wrote:

>Hi
>
>If they had done USB instead of HPIB / GPIB, a lot of the drivers would have
>been "out of service" by the time Windows 95 came along. No chance at all of
>them working under Windows 7. 
>
>For the complexity, it'd have been better if they used something more like
>Ethernet. Except in 1968, you would have set up for something other than
>TCP-IP. Anybody running a Token Ring network in the basement?
>
>No easy solution. Serial com is still with us because it's a lowest common
>denominator. I'm sitting here coding it into a new product right now (once
>the uber super compiler finishes a build). It's supported on just about
>every chip set in the universe. I suspect it will outlive the cockroaches. 
>
>Bob
>
>-----Original Message-----
>From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>Behalf Of David
>Sent: Wednesday, October 10, 2012 10:54 AM
>To: Discussion of precise time and frequency measurement
>Subject: Re: [time-nuts] 57600 baud rate with Basic etc
>
>What aspects of USB would HP have used?  Just the complexity of a USB
>OHCI/UHCI would have been economically prohibitive compared to an
>asynchronous serial UART.  An OHCI/UHCI is more like an ethernet
>controller and those took up the space of entire expansion boards
>initially.  
>
>What they did come up with was HP-IB although I would have preferred
>it to be serial and galvanically isolated.
>
>On Wed, 10 Oct 2012 10:28:46 -0400, paul swed <paulswedb at gmail.com>
>wrote:
>
>>I have never figured out why HP did not develop USB in 1969? Not very far
>>sighted. ;-)
>>Regards
>>Paul
>>WB8TSL