Definition of "kilobyte"

The data word processor 606 handles the in-flow and out-flow of byte-oriented input/output data and interleaved signals at a rate of, for example, 500 kilobytes per second. Instruction processing rates of four to eight per microsecond are required for such a data flow.

1969, Harold R. Dell, HIGH-DENSITY PERMANENT DATA STORAGE AND RETRIEVAL SYSTEM‎, US Patent 3638185

It is assumed herein that each block includes 32 bytes, each sector includes 1 kilobyte, the buffer memory 116 includes 4 kilobytes, and read data is represented by one double word or 64 bits, as one word in this case consists of 32 bits.

1969, Hisashi Horikoshi, MEMORY CONTROL SYSTEM‎, US Patent 3618041