17 May
2009
17 May
'09
9:17 a.m.
Chris Elmquist <chrise at pobox.com> wrote:
I may have missed some facts earlier in this thread--
but does the system
obey hardware flow control such as CTS? ie, if CTS is low, will it be
blocked from transmitting? If that is obeyed by all of your OS and
software, then it is not hard to build a microcontroller that would sit
between the system and the terminal, adding the delays you need on <cr>
while buffering for and hardware flow controlling back toward the PDP-8.
In general, when talking about DEC equipment, the answer to that
question is *always* no, for the simple fact that DEC didn't do hardware
flow control. Hardware flow control is actually against the RS-232 spec,
and DEC didn't abuse standards (unlike most other companies).
(And to make it clear: hardware flow control is definitely not possible
towards a PDP8)
Johnny
Chris
On Thursday (05/14/2009 at 03:04AM +0200), Philipp Hachtmann wrote:
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt at softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
> Hi,
>
> >> I completely mis-understood the source of your troubles.
> Oh.
> The VT05 terminal operates at speeds from 110 baud to 2400 baud,
> selectable with a rotary switch in the back (my unit is currently missing
> a counter ic to generate 110baud, but...).
> So far so good. The problem is, that when you want to operate the VT05 at
> speeds higher than 300 baud, you have to wait a certain amount of time
> after a line feed character or cursor positioning command. This is
> usually done by inserting zero fill characters (4 at 2400 baud) after the
> critical commands. If you don't obey this rule, the VT05 has not
> completed changing the line when you send the next character. This is a
> bit like a too slow cr on a teletype - funny but true.
> So my wish was to modify OS/8 so far that it generates those fill characters.
> The TTY: handler is also capable of correctly doing this for me. But many
> other programs - as the OS/8 keyboard monitor itself - use direct IO
> commands to read from and write to the terminal.
> So one would have to patch many programs. In case of the keyboard
> monitor, I don't know if there is any room left to put such a code in.
> And I don't know how to reassemble and correctly install a new keyboard
> monitor from scratch.
> So all I can do is to run the VT05 at 300 baud. Or get the advances
> serial interface (see other posting).
> Did this illustrate the problem?
>
> Best wishes,
> Philipp :-)
>
>
>
> --
> http://www.hachti.de
-- Chris Elmquist