Kim-1

The KIM, short for Keyboard Input Monitor. was designed as a demonstration board for the new 6502 microprocessor.

It was meant for engineers but was quickly adapted by hobbyists because it was a relatively cheap way to start building a computer system.

The big innovation of the KIM, as its name implies is that it had a built in monitor ROM. Earlier systems just used a switch for each address and data line, and a button to enter into memory the data-byte you had selected with the data switches into the address selected with the address switches. Normally you would have to toggle switches and push buttons for five minutes or so just to enter a 32 byte "bootstrap loader", a small program that was used to load more software (mostly a "debug monitor") into the computers memory by other means (paper tape, or maybe a cassette tape). a very laborious affair, and a singe error while flipping the switches meant that the bootstrap loader would fail, and the operator had to do the whole process all over again. The KIM had an onboard ROM with a debug monitor so flipping switches was unnecessary.

The KIM came assembled, but without a case or a power supply, just the bare board. It had a small hexadecimal keypad and six seven segment LED displays. The first four to display the address, the other two to display the data (while running the monitor, a user program could use the display for its own purpose).

It had 1 Kilobyte (yes just 1024 bytes!) of memory to store programs in. An 8K memory extension board was also available.

Programs could be stored on cassette tape using the 300 bps cassette tape interface.

To run BASIC or do anything beyond displaying something on the LED display one could connect a teletype (telex device) to the teletype interface (running at 110 baud). Many hobbyist used a ?glass teletype?, a primitive video display device emulating a teletype instead because a real teletype was too expensive and bulky. To run BASIC one had to expand the memory to 9K and load a BASIC interpreter from tape, a 15 minute affair.

Many books were available containing small assembler programs. One demo program converted the KIM into a music box by toggling a software controllable output bit connected to a small loudspeaker.

The KIM was succeeded by the AIM, essentially an expanded KIM with a small cash register printer. And a full ASCII keyboard. BASIC programs could be used with this printer as output device and the keyboard as input device. The AIM also had a bigger LED display that could display a single line of text.