The KIM -1 (Keyboard Input Monitor ) was one of the first home computers based on the 6502 CPU and was designed by MOS Technology, Inc., later acquired by Commodore, developed in 1976.


The KIM -1 consisted of a single-board computer, which contained all the necessary integrated circuits on a printed circuit board: The 6502, two 6530 multi-function blocks ( each with 1 KB ROM, 64 bytes of RAM and multiple I / O channels ) and 1 KB regular RAM. Overall, the KIM -1, therefore, had a capacity of 1152 bytes of RAM and 2048 bytes ROM. The clock frequency of 6502 microprocessor was 1 MHz. Similarly, the KIM- 1 contained a six-digit 7-segment LED display and offered 24 keys for direct entry of HEX code. Several of the I / O ports could be used for serial communication, or for connecting an external terminal or printer (TTY 20mA loop) as well as a cassette interface. An expansion port that provides all data, address and clock signals is also provided. This allows the extension to a system with more memory or other peripheral devices.

The MCS Alpha 1 was copied as a clone of the KIM -1 and received a housing with its own power supply and had some additional improvements. The memory was still limited to 1 KB RAM. Instead of 6 LEDs used the MCS Alpha 8 and could be easily operated using a monitor program. In addition to the CPU of the computer contained two chips 6532 and EPROM, a keyboard, a serial interface, and a cartridge.


The KIM -1 was characterized by a relatively complex BIOS. This " monitor " programs is called TIM (Terminal Input Monitor ) and KIM (Keyboard Input Monitor ) and were housed in the two 1 -KB ROM chips 6530. This monitor software made ​​it possible to connect a cassette recorder as an external storage medium to control the LED display and query the keyboard.

Once the KIM-1 was turned on, the monitor and the user was able to operate the device directly via keystrokes. Thus, the KIM -1 was one of the first single-board computer, which only require an external power supply for operation. This fact and the fact that he allowed a low -cost alternative to entry into the then computer technology, made ​​him very popular with many amateur programmers of the 1970s.

The Microsoft BASIC programming language was first released for the KIM -1.

Screen display

The developer of the TV Typewriter, Don Lancaster, developed an inexpensive screen display for the KIM -1. The additional circuit board set up to 4000 characters on a TV or monitor represents a typical representation could produce 16 lines of 32 characters each in uppercase. The board was only equipped with ten -cost ICs and used the KIM -1 as a storage for screen display.