Windows 1.0 Beta Release

Windows 1.0 Beta Release is a pre-release build of Windows 1.0, compiled on 8 May 1985. It includes an updated RTM-like installer, mostly finalized UI, color support on the IBM PC and additional applications, alongside redesigns of existing ones from the Alpha. Source code and documentation for the developers was moved to a separate package called the "Software Development Kit" (SDK).

This build was possibly also released for various non-PC-compatible machines, such as Zenith Z-100 and RM Nimbus PC-186 (for the latter, former RM employee Bob Richmond wrote on his blog: "In May [1985] I built a Beta release for the PC-186 which had fairly widespread distribution in the UK with the early Nimbus computers sold to the RM education market of schools and colleges." ), but this has not been fully confirmed yet.

This build was uploaded to the BetaArchive FTP on 19 September 2008.

Installation
Before you run setup, it is recommended to create the directory you want Windows to be installed to, as there is a chance that setup fails to create the directory. For high-resolution color EGA mode, select "Enhanced Graphics Monitor with Enhanced Display" during Setup.

This beta will run on the following operating systems: For MS-DOS 5.0 or 6.x, run:  before loading Windows. For DOSBox, run. Failure to do this can result in the build crashing on startup.
 * MS-DOS 2.x / 3.x / 5.0 / 6.x
 * PC-DOS 2.x or 3.x

Printer installation
When setup says that the Q key can be pressed to not install any printers on the printer selection screen, just pressing Q on the keyboard does not work. Pressing ⇧ Shift (capital Q) is needed to skip printer installation.

Clock problems
When closing the About dialog of the Clock application, Windows crashes with a stack overflow error. Clock's icon in the icon area appears different than in both earlier and later builds, the overall background is transparent, the live clock image is placed on top and a thin black square border can be seen at the top and bottom of the icon.

Double click to close a window
The option to double-click on the system box to close a window has not been implemented yet, so one must open the system menu and choose the "Close" option to quit applications.

File associations in WIN.INI
Although Calendar is a simple floating date picker in this build, it's associated with  files. This suggests a more advanced Calendar like the one in later builds was already in development at this point but left out.

The Terminal application is not included with this build, but is associated with  files. Much like the above case with Calendar, this suggests the Terminal application was already in development but not included with this build. The file extension for Cardfile files is  in this build. In later builds it was changed to.

Color scheme
Despite the fact that this build officially introduced color support on the IBM PC as it includes drivers for color EGA display modes, the default color scheme remains monochrome. The user can manually add colors to the color scheme in the Control Panel. Applications use various background colors regardless of the system color scheme.

About dialogs
This is the first leaked build where applications feature an About dialog with copyright and version information. However, at this point the overall design of this dialog has not been standardized yet, as different applications display different strings there. Calculator, Clock and Reversi say "Version 1.00" and "April 1985", MS-DOS Executive and Cardfile say only "Beta Release", Control Panel and Notepad say only "Version 1.00", while Paint says "Beta Version, 5/6/85".