Here the images

50 years of working with a KIM-1:
The KIM-1 Explained

The Jolt, one of the first 6502 SBC’s, so nicely reproduced now:
The TIM/Jolt explained.

There is a bug in the TTY CLI, it accepts characters as ‘;’ and ‘:’ as valid hex and translates to A..F.

KIM
0200 A9 ;;
00BB 00 ::
00AA 00 ????
FFFF 1C

More about this innocent feature here: PRTBYT, GETBYT and PACK

On this location you can find the open hardware source of a RAM card made for the MTU bus

he RAMpager is a MTU banked RAM expansion for the KIM-1: the board supports up to 1MB (that’s three orders of magnitude above more than the original 1152 bytes!) of memory and maps it to a 4KB window placed between 2000h and FFFFh. The window can be mapped to different banks for read and write operations via two control ports.

It supports an optional internal/external backup battery to keep the data in the SRAMs valid across power cycles.

On these pages I will try to explain how all this is working together. It will not be a rewrite of the KIM-1 user manual, read that first, but more a deeper personal dive into the software and hardware of what the makes the KIM-1 tick. It also expects a basic knowledge of the 6502 and digital electronics.

Based upon my experience and study of the KIM-1 since 1979. The first years to learn the 6502 CPU and the 6530 RRIOTs. The next time when I wrote the KIM-1 Simulator (2015 to now). Many notes on paper and files everywhere. Now consolidated in a lot of pages.

Work in Progress July 6-13, 2026

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.
You can have serial input wihout echo, non-blocking and even make the TTY input deaf for unwanted input.

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 ringbuffered serial I/O with a dedicated IC like the 6850, 6511 etc.
Without this extra hardware you can achieve acceptable results with these routines.

Settings 2.3.1