18 Jul
2014
18 Jul
'14
11:13 a.m.
On 07/18/2014 10:12 AM, Vincent Slyngstad wrote:
One possibility that I haven't seen discussed, is
that the DELs are
there to provide a delay for the IMSAI. It's conceivable that the BASIC
interpreter ponders it's navel for a short time after a
line is received. Adding a couple of frames of "ignore me" would give
the interpreter two character times to catch up.
If the interpreter was sometimes/often ready early, then "ignore me" was
the harmless thing to send.
I think I mentioned that at least one of the old timesharing BASIC-like
systems demanded that paper tape input lines end with CR-X-OFF-DEL-DEL.
Given that many systems of the time were half-duplex, the idea was to
have the X-OFF stop the reader until the host was ready to accept
another line, whereupon the host would send LF X-ON.
--Chuck