Problems with the KIM-1 TTY character input 

1. The KIM-1 hardware is hardware echoing incoming serial characters to the output, no echo in software involved, so you cannot influence what appears on screen. 
   Very annoying!

2. The KIM-1 GETCH routine is blocking, no way to check for a character coming in, like a Break. waiting. Also quite annoying if porting other software to the KIM-1 or you want the program interruptable.

3. While a program is running something CPU intensive and you type something the program is not really waiting for, the characters appear on screen.
   Because the KIM-1 does hardware echoing of TTY input, this is unavoidable it seems. 

Here I present solutions for these problems in software, made possible by the genius hardware design of the KIM-1 TTY I/O.

Are they perfect? Maybe not, it is still bitbanging the incoming serial signal. It can miss the correct starting point for the incoming character bit stream.
If you want a perfect solution, you will need interrupt driven serial I/O with a dedicated IC like the 6850, 6511 etc.
Without this extra hardware you can achieve accpetable results with these routines.

In this archive a demo program on no echo and non-blocking TTY input and routines to make the TTY input deaf at wish.

The actual routines are in kim1echononblockdeaf.asm

Hans Otten, 2026