The KIM-1 uses a cassette tape recorder as mass storage medium. Due to to limitations of a cassette recorder this was slow and unreliable.
So I designed a Solid State digital Tape Recorder that connects to the expansion connector of the micro-KIM or, with three wires, to the genuine KIM-1.
You can access the digital Tape Recorder by means of a browser or with telnet but of-course you can also use the four buttons and the OLED display on the digital Tape Recorder to navigate thru the stored programs or to record a new program.
limit is in the time the 6502 needs to receive the bits, put them in a byte and write the byte to RAM.