A floppy disk operating system for the 8080 and Z80

Techniques for the design and implementation of a floppy disk operating system for the 8080A or Z80 microprocessors are described. Implementation details are illustrated through reference to SOS, a prototype Small Operating System which runs with a single IBM-format floppy drive on an 8080. Techniques for floppy disk communication, disk directory design, and system resource management are described and illustrated.