17 Jun
2013
17 Jun
'13
8:30 a.m.
Note that the conversion from 300 baud to 110 baud (or 75 or 45 or however
low you can go) is so incredibly slow that any modern microcontroller can
bit bang two serial ports with flow control and/or a couple dozen K of
buffering.
Wiring up the MAX232s or clones or MAX235s and the sheer tediousness of
DTE/DCE male/female 9pin/25pin is probably more agonizing than writing the
microcontroller software, even assuming you write your own uart instead of
just including two bitbang serial library and the code for a big FIFO
buffer outta the standard microcontroller library.
In the "olden days" printer buffers which would spool up a print job
reading as fast as possible were popular back when printers were dumb and
slow. If you could find two (bidirectional) vintage serial port printer
buffer/spool that did 110 baud on one side and wire up an adapter to use
both...
On Mon, Jun 17, 2013 at 10:01 AM, ben <bfranchuk at jetnet.ab.ca> wrote:
On 6/17/2013 8:57 AM, Guy Sotomayor wrote:
On Jun 16, 2013, at 10:33 PM, Ian King <IanK at vulcan.com> wrote:
On 6/16/13 6:00 PM, "Tom Watson" <tsw-cc at johana.com> wrote:
How about a TEXT vs BINARY file format transfer problems if you use
DOS/Windows?
Ben.
On 6/15/2013 10:37 PM, Ben wrote:
Is it because of baud (bit) rate or an incompatibility?
If the former, most baud rate generators won't generate 110 unless
specific
crystals/divisors are chosen. Otherwise they'll start at 300.
If the latter, I've found that some USB serial adapters aren't friendly
to classic
gear. I haven't thrown an analyzer between them to figure it out. I've
found
some that seem to work most often (Belkin springs to mind...still doesn't
support 110 though).
TTFN - Guy
On 6/15/2013 8:48 PM, Cory Smelosky wrote:
>
> That bothers me too...I'm accumulating adapters and gender > changers
>> though. ;)
>>
>>
USB has RS232 adapters, now you can have the best of both worlds.
> 2 GHZ download for your 110 baud TTY.
>
-tony
>>>
>> Ben.
>
Only one problem there, most (if not all) EIA-232 adapters for USB won't
go below 300 Baud. It is a problem when trying to get the old ASR33 to
type things out!
Of course you need to also add two stop bits, but that is pretty easy
(as
he notes the only place two stop bits were used was for the 33/35
teletypes).
I've experienced this, trying to use a USB serial adapter in place of an
ASR-33 to serve up an imaged paper tape on a PDP-8/e. It does not work.
It's an interesting question as to why this is a problem. :-)