27 Feb
2013
27 Feb
'13
12:53 a.m.
Hi all,
Regarding the comments on baud rate and flow control - still doesn't make
sense to me why the VT100 would not exhibit the error with a real PDP-11
(at 9600 baud), but does do it with the emulated PDP-11. The info is coming
at the terminal at the same rate - why would the behavior be different?
- Earl
On Tue, Feb 26, 2013 at 6:45 PM, Richard <legalize at xmission.com> wrote:
In article <CAMDAk4f81=gcUh_GV14mGhZoH1rGpLfZk74pQG=
sjjpqJ-NS0g at mail.gmail.com>,
Earl Evans <earl at retrobits.com> writes:
The garbage always starts in exactly the same
place in the DIR listing.
After that, garbage characters (grey squares) become interspersed with
the
good text.
Try setting your baud rate to 300 and see if it still happens.
If so, then you have a hardware problem.
If not, then it's as suspected elsewhere in this thread -- the
emulated machine is feeding the VT100 faster than it can accept the
data.
The VT100 doesn't need padd characters IIRC (VT05 and VT52 definitely
do), but it uses a signalling scheme to tell the host that it's
internal buffer is full. This signalling scheme can be either in the
hardware signalling (DTR/CTS) or it can be XON/XOFF (DC1/DC3) control
characters in the data stream.
Relevant manuals for VT100 are linked here:
<http://terminals.classiccmp.org/wiki/index.php/DEC_VT100>
Under Windows, the default settings of a com port are not set to use
any flow control. I was recently generating ESC sequence laden files
for my Tektronix 4205 terminal on my PC and sending them to the COM3:
port with "copy foo.dat com3:" and the Tek was losing data and
garbling commands until I configured both the terminal and the COM
port to use the same flow control signalling. Then everything worked
properly.
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