Editing 86-DOS (section)

===Origins===
86-DOS was created because sales of the [[Seattle Computer Products]] 8086 [[electronic kit|computer kit]], demonstrated in June 1979 and shipped in November,<ref name="Hunter_1983_Roots_of_DOS"/> were languishing due to the absence of an operating system. The only software that SCP could sell with the board was Microsoft's [[Standalone Disk BASIC-86]], which Microsoft had developed on a prototype of SCP's hardware.<ref name="Hunter_1983_Roots_of_DOS"/> SCP wanted to offer the 8086-version of [[CP/M]] that Digital Research had initially announced for November 1979, but it was delayed and its release date was uncertain.{{r|paterson198306}} This was not the first time Digital Research had lagged behind hardware developments; two years earlier it had been slow to adapt CP/M for new [[floppy disk]] formats and [[hard disk drive]]s. In April 1980, SCP assigned 24-year-old [[Tim Paterson]] to develop a substitute for [[CP/M-86]].<ref name="Hunter_1983_Roots_of_DOS"/>

Using a CP/M-80 manual as reference,<ref name="nerds2"/> Paterson modeled 86-DOS after its architecture and interfaces, but adapted to meet the requirements of Intel's 8086 [[16-bit]] processor, for easy (and partially automated) source-level translatability of the many existing [[8-bit]] CP/M programs;<ref name="paterson198306"/> porting them to either DOS or CP/M-86 was about equally difficult<ref name="edlin19820607"/> and eased by the fact that Intel had already published a method that could be used to automatically translate software from the [[Intel 8080]] processor, for which CP/M had been designed, to the new 8086 instruction set.{{r|paterson198306}} At the same time he made a number of changes and enhancements to address what he saw as CP/M's shortcomings. CP/M [[cache (computing)|cached]] file system information in memory for speed, but this required a user to force an update to a disk before removing it; if the user forgot, the disk would become corrupt. Paterson took the safer, but slower approach of updating the disk with each operation. CP/M's [[Peripheral Interchange Program|PIP]] command, which copied files, supported several special file names that referred to hardware devices such as [[printer (computing)|printers]] and [[Computer port (hardware)|communication ports]]. Paterson built these names into the operating system as [[device file]]s so that any program could use them. He gave his copying program the more intuitive name [[COPY (DOS command)|COPY]]. Rather than implementing [[CP/M#File_system|CP/M's file system]], he drew on Microsoft Standalone Disk BASIC-86's [[File Allocation Table]] (FAT) [[file system]].<ref name="Beley_1986_MS-DOS_Encyclopedia"/>

By mid-1980 SCP advertised 86-DOS, priced at {{currency|amount=95|code=USD|linked=yes}} for owners of its {{currency|amount=1290|code=USD|linked=no}} 8086-board and {{currency|amount=195|code=USD|linked=no}} for others. It touted the software's ability to read [[Zilog Z80]] source code from a CP/M disk and translate it to 8086 source code, and promised that only "minor hand correction and optimization" was needed to produce 8086 binaries.{{r|BYTE_1980_86-DOS}}