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SOME HISTORY
Development of MS-DOS/PC-DOS began in October 1980, when IBM
began searching the market for an operating system for the yet-
to-be-introduced IBM PC. Microsoft had no real operating system
to sell, but after some research licensed Seattle Computer
Products' 86-DOS, which had been written by a man named Tim
Paterson for use on the company's line of 8086, S100 bus micros.
This was hurriedly polished up and presented to IBM for
evaluation. IBM had originally intended to use Digital Research's
CP/M operating system, which was the industry standard at the
time. Folklore reports everything from obscure legal
entanglements to outright snubbing of the IBM representatives by
Digital, regardless, IBM found itself left with Microsoft's
offering of "Microsoft Disk Operating System 1.0". An agreement
was reached between the two, and "IBM PC-DOS 1.0" was ready for
the introduction of the IBM PC in October 1981. IBM subjected the
operating system to an extensive quality-assurance program, found
well over 300 bugs, and decided to rewrite the programs. This is
why PC-DOS is copyrighted by both IBM and Microsoft.
It is sometimes amusing to reflect on the fact that the IBM PC
was not originally intended to run MS-DOS. The target operating
system at the end of the development was for a (not yet in
existence) 8086 version of CP/M. On the other hand, when DOS was
originally written the IBM PC did not yet exist! Although PC-DOS
was bundled with the computer, Digital Research's CP/M-86 would
probably have been the main operating system for the PC except
for two things - Digital Research wanted $495 for CP/M-86
(considering PC-DOS was essentially free) and many software
developers found it easier to port existing CP/M software to DOS
than to the new version of CP/M.
After eight years the wheel has turned a full circle. Digital
Research aided IBM in writing DOS 4.0, which was subsequently
licensed back to Microsoft, which has dropped further development
of the operating system to tilt at the windmills of OS/2.
MS-DOS and PC-DOS have been run on more than just the IBM-PC and
clones. There was an expansion board for the Apple ][ that
allowed one to run (some) well - behaved DOS programs. There are
expansion boards for the Commodore Amiga 2000, the Apple
Macintosh II, and the IBM RT PC allowing them to run DOS, and the
IBM 3270 PC, which ran DOS on a 68000 microprocessor. The Atari
STs can run an emulator program called PC-Ditto and boot any
version of MS-DOS with full functionality.
Various other operating systems are available for the IBM PC.
These include:
Digital Research CP/M-86
Digital Research Concurrent CP/M-86 (multi-tasking)
Digital Research Concurrent DOS (PC-DOS compatible, multi-tasking)
Digital Research Concurrent DOS (PC-DOS compatible, multi-tasking,
multi-user)
Digital Research Concurrent DOS 386 (same, for 80386 computers)
Digital Research DR-DOS 3.31, 4.0, 5.0 and 6.0 (PC-DOS clones)
Wendin-DOS (PC-DOS compatible, multi-tasking, multi-user)
QNX (multi-tasking, multi-user)
UNIX (various systems from IBM itself, Microsoft-SCO, Bell, and
various UNIX clones, single and multi-user)
PC-MOS/386 (PC-DOS clone, multi-user, multi-tasking)
"Shell" programs exist which use DOS only for disk management
while they more or less comprise a new operating system. These
include:
DesQview
Windows
OmniView
TopView
TaskView
NEC V-series CPUs can execute Intel 8080/8085 8-bit instructions
as well as the 16-bit 8088-up instructions. They can run standard
Digital Research 8-bit CP/M and MP/M directly, as well as other
operating systems developed for that processor.
Specific Versions of MS/PC-DOS:
DOS version nomenclature: major.minor.minor. The digit to the
left of the decimal point indicates a major DOS version change.
1.0 was the first version. 2.0 added support for subdirectories,
3.0 added support for networking, 4.0 added support for Lotus-
Intel-Microsoft EMS. The first minor version indicates
customisation for a major application. For example, 2.1 for the
PCjr, 3.3 for the PS/2s. The second minor version does not seem
to have any particular meaning.
The main versions of DOS are:
86-DOS August 1980 Seattle Computer Products
PC-DOS 1.0 August 1981 Original release
PC-DOS 1.1 March 1982 Bugfix, double sided drive support
MS-DOS 1.25 March 1982 For early compatibles
PC-DOS 2.0 March 1983 For PC/XT, many UNIX-like functions
PC-DOS 2.1 October 1983 For PCjr, bugfixes for 2.0
MS-DOS 2.11 October 1983 Compatible equivalent to 2.1
PC-DOS 3.0 August 1984 1.2 meg drive for PC/AT
PC-DOS 3.1 March 1985 Bugfix for 3.0, network support
MS-DOS 2.25 October 1985 Compatible; foreign language support
PC-DOS 3.2 December 1985 720k 3.5 inch drive for Convertible
PC-DOS 3.3 April 1987 For PS/2, 1.44, multiple partitions
PC-DOS 4.0 June 1988 32+ meg DOS partitions, EMS support
PC-DOS 5.0 June 1991 XMS, upper memory blocks, HMA
Some versions of MS-DOS varied from PC-DOS in the available
external commands. Some OEMs only licensed the basic operating
system code (the xxxDOS and xxxBIO programs, and COMMAND.COM)
from Microsoft, and either wrote the rest themselves or
contracted them from outside software houses like Phoenix. Most
of the external programs for DOS 3.x are written in "C" while the
1.x and 2.x utilities were written in assembly language. Other
OEMs required customised versions of DOS for their specific
hardware configurations, such as Sanyo 55x and early Tandy
computers, which were unable to exchange their DOS with the IBM
version.
At least two versions of DOS have been modified to be run
entirely out of ROM. The Sharp PC5000 had MS-DOS 1.25 in ROM, and
the Toshiba 1000 and some Tandy models have MS-DOS 2.11 in ROM.
PC-DOS 3.0 was extremely buggy on release. It does not handle the
DOS environment correctly and there are numerous documented
problems with the batch file parser. The network support code is
also nonfunctional in this DOS version. It is recommended that
users upgrade to at least version 3.1.
DEC MS-DOS versions 2.11 for the Rainbow had the ANSI.SYS device
driver built into the main code.
IBM had a version 1.85 of PC-DOS in April 1983, after the
introduction of DOS 2.0. It was evidently for internal use only,
supported multiple drive file searches (a primitive form of
PATH), built-in MODE commands for screen support, a /P parameter
for TYPE for paused screens, an editable command stack like the
public domain DOSEDIT.COM utility, and could be set up to remain
completely resident in RAM instead of a resident/transient part
like normal DOS. It is a pity some of the heat enhancements
didn't make it into DOS 2.0. IBM also had an internal use only
version 3.4, evidently used while developing DOS 4.0.
Some versions of DOS used in compatibles do not maintain the 1.x,
2.x numbering system. Columbia Data Products computers labelled
DOS 1.25 as DOS 2.0. Early Compaq's labelled DOS 2.0 as DOS 1.x.
Other versions incorporated special features - Compaq DOS 3.31
and Wyse DOS 3.21 both support 32-bit File Allocation Tables.
AT&T DOS 3.1 differs from generic MS-DOS 3.10 in its use of
cluster-size and file allocation table structures. AT&T DOS
appears to use rules not from version 3, but rather those from
version 2.
Epson Equity III and ComputerLand 3.10 DOS's appear to use
cluster techniques that are a cross between versions 2 and 3. On
type DOS partitions, these DOS's use 3.x rules if the partition
is larger than 32,680 sectors in total size. This implies 16 bit
FAT entries as well. On partitions below this size, they will use
2.x rules, including the 12 bit FAT entries.
Zenith DOS 3.x and Wyse DOS 3.2 have a built-in internal device
driver to handle up to 4 32Mb DOS partitions on a single hard
disk. Wyse DOS 3.31 will handle single partitions up to 512Mb
with a 32-bit FAT.
According to PC Week Magazine, July 4,1988, Arabic versions of
MS-DOS are shipping with a hardware copy-protection system from
Rainbow Technologies. This is similar to the short-lived system
used by AutoCAD 2.52 and a very few other MS-DOS programs, where
an adapter block is plugged into the parallel port and software
makes use of coded bytes within the block. This type of copy
protection has been common on Commodore products for several
years, where it is called a "dongle."
The AutoCAD dongle was defeated by a small program written within
weeks of version 2.52's debut. Version 2.62 was released somewhat
later, without the dongle. The DOS dongle will, however, prevent
the system from booting at all unless it is found.
This makes the Arabic version of MS-DOS the first copy-protected
operating system, a dubious distinction at best. The
modifications to the operating system to support the dongle are
not known at this time.
Microsoft changed their OEM licensing agreements between DOS
versions 2.x and 3.x. OEM versions of DOS 3.x must maintain
certain data areas and undocumented functions in order to provide
compatibility with the networking features of the operating
system. For this reason, resident programs will be much more
reliable when operating under DOS 3.x.
IBM's release of DOS 4.0 (and the immediate subsequent release of
a bugfix) is a dubious step "forward." DOS 4.0 is the first
version of DOS to come with a warranty; the catch is that IBM
warrants it only for a very slim list of IBM-packaged software.
4.0 has some minor EMS support, support for large hard disks, and
not much else. With its voracious RAM requirements and lack of
compatibility with previous versions of DOS (many major software
packages crash under DOS 4.0), plus the increase in price to a
cool $150, there has been no great rush to go to the newest DOS. |
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