86-DOS 0.10

86-DOS 0.10 is the first betaHemmings, Bill (5 May 1999). Dos 1.1. comp.os.cpm. build of QDOS/86-DOS. It was in a roughly half-complete state when compiled.Hunter, David (March 1983). The Roots of DOS: Tim Paterson. Softalk for the IBM Personal Computer. p. 12-15. An estimate of only 10 people have ever seen it, and it was never shipped.Paterson, Tim (4 August 2018). VCF West XIII -- Tim Paterson -- Original DOS and the old days. Vintage Computer Federation.
==Features==
86-DOS 0.10 was a preliminary release, including a very limited number of commands crammed into 6 KB of object code.Allen, Paul (2011). Idea Man. Penguin. p. 135. ISBN 1-59184-537-8.
===Disk===
86-DOS 0.10 used a modified version of BASIC-86's FAT file system, chosen because of the small cluster sizes, speed, and error handling capabilities. The modifications included supporting 12-bit table elements (allowing for 64MB disks), and reducing the number of FATs from 3 to 2.Paterson, Tim (30 September 2007). Design of DOS. DosMan Drivel. The filesystem was additionally adapted to allow for CP/M (8.3) filenames.Paterson, Tim; Wharton, John (3 October 1994). From the Mailbox: The Origins of DOS. Microprocessor Report. p. 1-2.
====Directory format====
Offset	Length	Field
0 	8 	Name
8 	3 	Extension
11 	2 	First Cluster
13 	3 	File Size
File sizes are recorded in terms of bytes; however, like CP/M, files are accessed with record-granularity, with the size of a record being fixed at 128 bytes. This means all file sizes are divisible by 128.
===Commands===
86-DOS's commands were split into internal and external commands. External commands were .COM files in the root directory, while internal commands were not visible.Paterson, Tim (December 1980). 86-DOS Version 0.3 User Manual. Seattle Computer Products.
Command	Type 	Source 	Notes
DIR 	Internal	 	
RENAME 	Internal	 	
ERASE 	
Internal	 	
COPY 	Internal	Manes, Stephen; Andrews, Paul (1993). Gates: How Microsoft's Mogul Reinvented an Industry—and Made Himself the Richest Man in America. Doubleday. p. 280-281. ISBN 0-385-42075-7.	
TYPE 	Internal	Paterson, Tim (June 1983). A Short History of MS-DOS. BYTE Magazine. p. 246. 	"It had all the basic utilities for assembly-language development except an editor"
ASM 	External	 	Originally written in Z80 assembler as ASM86Microsoft Macro Assembler (MASM) Unofficial Changelist. BytePointer.
TRANS 	External	 	Originally written in September 1979United States District Court for the Western District of Washington (18 January 2007). Paterson v. Little, Brown, and Co., et al. - Deposition Upon Oral Examination of Tim Paterson. PACER. Case 2:05-cv-01719-TSZ Document 14-2. in Z80 assembler as TRANS86
HEX2BIN	External	 	"It had all the basic utilities for assembly-language development except an editor"
While not counted as a command in the later version 0.3 manual, it should also be noted that 86-DOS had the ability to run executable files by inputting their filenames.Bornstein, Howard (1986). MS-DOS (Versions 1.0-3.2) Technical Reference Encyclopedia. Microsoft Press. p. 8. ISBN 0-914845-69-1.Duncan, Ray (1988). The MS-DOS Encyclopedia. Microsoft Press. ISBN 1-55615-049-0.
===Program Segment Prefix===
86-DOS 0.10 created the Program Segment Prefix (PSP), a 256-byte data structure used to store program states. It takes clear inspiration from CP/M-80's Zero Page, using a similar far call entry and exit.Necasek, Michal (13 September 2011). Who needs the address wraparound, anyway?. OS/2 Museum.Brown, Ralf (July 2000). Format of Program Segment Prefix (PSP). Delorie Software.Jurgens, David (1991). DOS Program Segment Prefix Layout. HelpPC Reference Library.
==References==
Category:86-DOS versions
Category:Unleaked builds