MS-DOS 4.0 (multitasking operating system)
| MS-DOS 4.0 | |
|---|---|
| developer | Microsoft |
| License (s) | proprietary |
| First publ. | 1986 |
| Current version | 4.1 (1987) |
| Kernel | monolithic ( assembler ) |
| ancestry | QDOS / 86-DOS ↳ PC DOS (licensed for IBM) ↳ MS-DOS |
| Architecture (s) | IBM PC ( x86 from 8086 / 8088 ) |
| Others | Not to be confused with PC DOS 4.0 or MS-DOS 4.01 |
MS-DOS 4.0 is a 1986 and 1987 out given multitasking - operating system from Microsoft .
Since this operating system was not widely used by the OEMs , it is rarely used. In some sources this operating system is referred to as European MS-DOS 4.0 because it was mainly used there. It should not be confused with the regular PC DOS 4.00 or MS-DOS 4.01, which did not have multitasking capabilities.
history
Apricot Computers announced MS-DOS 4.0 in early 1986, and Microsoft gave a demonstration of this operating system in September of the same year. MS-DOS 4.0 was based on MS-DOS 3.1 (according to other sources on 2.0).
This system has only been accepted by a few European OEMs, including SMT Goupil and International Computers Limited (ICL). IBM did not license this operating system, much more focused on improvements in DOS 3.x and working with Microsoft on the development of OS / 2 .
As a result, the project was scaled back. What the OEMs had already been promised was still being completed. September 1987 came an enhanced version, MS-DOS 4.1, based on enhancements in MS-DOS 3.2. It was issued for the ICL DRS Professional Workstation (PWS). The product was then discontinued.
In July 1988 IBM announced the IBM DOS 4.0 as the successor to IBM DOS 3.3. The actual MS-DOS 4.01 was delivered based on MS-DOS 3.3.
Functions
Apart from a few small improvements, such as support for the New Executable format, the main focus was on support for preemptive multitasking . The protected mode of the 80386 processor was not used, much more programs specially adapted to it could run in a background mode , provided they did not have to perform I / O operations. To do this, the operating system provided a scheduler that assigned time slices to application programs. The interprocess communication took place via pipes and shared memory . This form of multitasking was generally considered to be suitable for servers rather than workstations.
The limitations of MS-DOS 3.0 remained, including the limitation on conventional memory (the lower 640 KiB). In addition, software that was supposed to benefit from multitasking had to be adapted.
INT 21 hex / AH = 87 hex could be used to distinguish between multitasking MS-DOS 4.x and the regular MS-DOS / PC DOS 4.x.
literature
- Microsoft to Make MS-DOS 4.0, MS-Net 2.0 Available in Fourth Quarter . In: InfoWorld . September 29, 1986.
- Larry Osterman: Did you know that OS / 2 wasn't Microsoft's first non Unix multi-tasking operating system? .
- Vernon Brooks: Information about the little known multitasking MS-DOS 4.0 . In: PC DOS Retro . Retrieved February 13, 2014.
Individual evidence
- ↑ MS-DOS 4.0 in UK; US Waiting for 5.0 . In: InfoWorld . March 24, 1986.
- ^ Larry Osterman: Did you know that OS / 2 wasn't Microsoft's first non Unix multi-tasking operating system? .
- ^ IBM DOS. In: InfoWorld July 18, 1988, p. 77.
- ↑ Ralf Brown: The x86 Interrupt List . December 29, 2002. Retrieved October 14, 2011.