[TUHS] V6 Console IO

Paul Riley paul at rileyriot.com
Fri Jul 24 10:18:26 AEST 2020


I am using C in V6 to create a Forth compiler. I don;t have any interest in
Forth as a general purpose language, however I do like it. It's satisfying
to create a language from the ground up. I'm interested in it a simple and
extensible interpreted language for toying with my PDP-11s, so I'll have
some with it in the future.

I have a very basic problem. I am simply using getchar and putchar for
console IO, which is convenient indeed. I'm struggling however with how C
processes the IO. It seems that when I type at the console, my typing is
immediately echoed to my terminal window. When I press backspace the system
responds with the character that was deleted, which is fine, as I assume it
was from the paper teletype days. However, my code is receiving input and
also echoing the output, but nothing appears on the terminal until I press
enter, when the system displays the whole line of input, which is
essentially a duplicate of what the terminal originally displayed, but with
the consolidated edits. My code is reading and echoing the input character
by character.

Here's my question. How can I suppress the original C/Unix echo, and get my
output to appear immediately? This simple sample code form the C
programming manual behaves the same.

int main() {
int c;
while ((c = getchar()) != EOF) {
putchar(c);
}
}

Paul



*Paul Riley*

Mo: +86 186 8227 8332
Email: paul at rileyriot.com
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