Marc B. McDonald is an American who was Microsoft's first salaried employee (not counting Monte Davidoff, who wrote the math package for BASIC for a flat fee).
[1][2] A version of "Standalone Disk Basic" was ported to a Seattle Computer Products 8086 by Bob O'Rear, and Tim Paterson was often at Microsoft to aid in the effort.
Tim Paterson copied the key aspects of the FAT system (single table, each directory entry containing the head of the file's cluster list, and the last value indicating the number of sectors used in the last cluster) when he implemented the FAT12 file system for his operating system 86-DOS in 1980, which became the basis for MS-DOS and PC DOS in 1981.
When McDonald rejoined Microsoft, a number of employees including Bill Gates and Steve Ballmer tried to assign him the employee number "1" but found that the human resources software did not allow this.
[3] McDonald worked in the QA-oriented Windows Defect Prevention group, focusing on organizational best practices to drive software quality from the bottom up.