27 Feb
2013
27 Feb
'13
2:02 a.m.
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.
According to my VT102 manual, DTR is only turned off when the terminal is
offline or performing a line disconnect. It doesn't seem to turn off DTR or
any other signal in response to the input buffer becoming full.
Under "Input Buffer Overflow Prevention", it goes on to say that there are
three methods of input buffer overflow prevention and lists XON/XOFF, fill
characters and low speed operation.
A table shows the requirement for fill characters for various functions at
various baud rates. It suggests that all functions require at least one fill
character (null) at 9600 baud, even when not in smooth scroll mode.
Regards,
Peter Coghlan