| The name of the base system (platform): | Microsoft Windows |
| Developers: | Microsoft |
| Date of the premiere of the system: | 1995/08/24 |
| Technology: | OS |
Content |
Windows 95 - the hybrid 16/32-bit operating system with the graphical interface released on August 24, 1995 by Microsoft corporation.
History
2018: A release of the version of OS in the form of the application
In August, 2018 the Windows 95 operating system was released in the form of the application available to personal computers running Windows, Linux and macOS. The program is created by the developer of the corporate Slack messenger Felix Rieseberg.
It laid out source codes and a setup package on the GitHub portal. Having loaded windows95 v1.0 application, users get access to many known programs and classical games which were in Windows 95. In particular, it is about a desktop, the Start menu, the Wordpad text editor, the graphics editor MS Paint, the game "Sapper" and "dialing program" Phone Dialer.
There is also a version of the Internet Explorer browser of that time, however in Rizeberg's project it does not work — Internet pages are not loaded, notes the The Verge edition. Besides, the operability of such applications as AOL is not implemented ('FREE Trial!'), CompuServe 3.0 and Microsoft Network.
For porting of Rizeberg OS used Electron — a framework for cross-platform development of desktop applications using Chromium and Node.js
The size of 129 MB has the appendix offering access to Windows 95. After start it occupies about 200 MB of RAM whereas the original version of OS required much less OZU — about 4 MB. Most likely, Electron loading affects.
Unlike the full operating system its simulation in case of failure does not require reset of the computer — rather simply to restart the program. At the same time the developer specifies that the project bears especially educational function and officially is not approved by Microsoft company.
The release of the application launching the Windows 95 environment took place in 23 years after release of the OS. Microsoft issued this computer platform on August 21, 1995.[1]
1992-1995
Work on the new version of the operating system which had to become the successor of popular Microsoft of Windows 3.1 began in 1992 and continued a little more than 3 years.
Officially the name of the new Microsoft Windows 95 operating system was announced on September 8, 1994, and directly the release took place on August 24, 1995.
In the summer of 1995 the corporation deployed the grandiose marketing program around the world. Everywhere advertizing with a hit Start Me Up of the Rolling Stones group sounded. On a skyscraper of Empire States Building in New York the logo image of Microsoft Windows was projected, and in day of a release of Windows 95 the army of the staff of corporation dressed in a uniform handed copies of the program to the fans who staid in queue all night long.
In four days of sales more than 1 million copies of Windows 95 were around the world sold, and by October 17 this number reached 7 million.
Innovations
- The interface of a graphic cover of a system is considerably improved. The display screen represented a surface of a desktop on which files are shown in the form of the icons placed in special folders. For work with the Windows 95 programs one Start button was used (or Start-up — in the Russian version), and the special task bar which is usually located in the lower part of the screen intended for access to already started programs.
- The Plug and Play mode intended for automatic recognition of peripheral devices available in the computer and installations of the necessary drivers is implemented.
- Extreme length in the name of files is increased - now names may contain up to 255 characters.
- Means of multimedia are considerably processed and added.
- There was a support of 32-bit applications and new network protocols
Shortcomings
Despite all advantages, Windows 95 is still a variation on Windows 3.1. It means for most of users that the architectural anachronisms put in it can lead to unexpected crash of a system. Even according to specialists of Microsoft, for important business applications use of Windows NT which provides data protection and resistance to incorrect operation of applications is more preferable.
One of problems of Windows 3.1 was capability of the application to cause system crash, having forced to do reset. In Windows 95 there was a lot of old code using which accomplishment of applications is performed. For example, such critical components of the operating system as USER and GDI which respectively provide windows management and provide means of the graphical interface, are still 16-bit and 16-bit applications work in the same address space, as. Therefore the 16-bit application containing errors can potentially "suspend" the virtual machine on which subsystems of USER and GDI work, or, what is even worse, to force USER or GDI incorrectly to work that can lead to crash of all OS. Even 32-bit applications can cause a system stop. The most part of the lower memory of 1 MB in size belonging to an address space of system code of Windows 95 (i.e. the system System VM virtual machine), is open for transactions of Win32 application.
The multitasking is another potentially weak point. Windows 95 sends all calls of USER API via the 16-bit system System VM virtual machine which is placed in the same place where and the run 16-bit application. If the 16-bit application "suspends" the machine System VM, refusing to process the message (the error type which is found most often in existing applications of Windows), then all other processes stop. So far the user will not complete forcibly the hung-up 16-bit application and by that will not release the machine System VM, other executed programs, even 32-bit, will be blocked.
Architecture of Windows 95
The architecture of Windows 95 represents a little improved version of architecture of Windows 3.1. In the system virtual machine Win16 and Win32 applications are run. The most part of the code of the operating system and data is also placed here. Win32 applications work at a basis of an algorithm of preemptive multitasking in separate address spaces. All Win16 applications are run as uniform process in the general address space on the basis of a non-preemptive multitasking algorithm. Libraries of dynamic configuration of USER, USER32, GDI, GDI32, KERNEL and KERNEL32 which provide system services to all applications are loaded into the system virtual machine and displayed in address spaces of each applied process. It increases performance due to elimination of costs of time for transitions between protection rings by a call of system functions. However on the other hand, it also threatens integrity of a system, opening access to parts of the operating system for application programs. By virtual DOS machines (VDM) DOS programs are executed. They work in the mode of preemptive multitasking.
The management subsystem works with the Windows 95 files in a zero ring of protection and processes all calls connected with input-output. The majority of calls is processed in a protect mode, but some still bring to switching into the Virtual 86 mode, and are processed in a real mode of DOS. The manager of installable file systems of IFS gives calls of file input-output to the driver of the corresponding file system. The driver of the VFAT file system implements own Windows 95 VFAT system which is similar to the FAT file system with the added means of processing of long names of files. The CDFS driver replaces MSCDEX and manages operations on data entry with CD. The redirector executed in the form of the driver of the file system provides the appeal to network drives. It is possible to set additional drivers of file systems. The subsystem of block input-output executes the corresponding transactions at the physical layer in response to requests of drivers of file systems.
The management subsystem virtual machines (VMM) provides low-level service functions, for example, planning of threads and memory management. Here also drivers of virtual devices (VxD) for the equipment belong.
Updates
- Windows 95 Retail SP1 (1995 г.)
- OEM Service Release 1 (1996 г.)
- OEM Service Release 2 (1996 г.)
- OEM Service Release 2.1 (1996 г.)
- OEM Service Release 2.5 (1997 г.)
Links
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