Welcome to the Microsoft Speech SDK

Microsoft Speech SDK SAPI 5.1

System Requirements

Supported operating systems are:

Windows XP Professional or Home editions; all language versions.
Windows.NET Server editions; all language versions.
Microsoft Windows 2000 Professional Workstation or Server; all language versions.
Microsoft Windows Millennium edition.
Microsoft Windows 98 all editions.
Microsoft Windows ® NT Workstation or Server 4.0, service pack 6a, English, Japanese, or Simplified Chinese edition.
Windows 95 or earlier is not supported.

Microsoft Internet Explorer 5.0 or later version. Users of Windows NT 4 with any version of the service packs require Microsoft Internet Explorer 5.5 or later. Download the latest version of Microsoft Internet Explorer.
Microsoft Visual C++ 6.0, service pack 3 or later version is needed to run the SAPI 5 SDK samples. In general, any 32-bit C compiler will work for writing SAPI applications.
Microsoft Visual Basic is needed to write applications incorporating SAPI automation, or for compiling the Visual Basic sample code. Since SAPI supports COM automation, other languages and compilers may be used with SAPI automation provided it supports OLE automation. Microsoft Visual Studio 7, also called Visual Studio.NET, is needed to compile the C# examples.
Platform SDK is generally not needed although some samples and functionality may require it. See the specific samples for confirmation. If required, see Microsoft Platform SDK for loading information.

A PentiumII\PentiumII-equivalent or later processor at 233 MHz with 128 megabytes (MB) of RAM is recommended.
SAPI 5 can now take advantage of a computer and operating system that supports multiple processors, including all those mentioned above. Additionally, you can use SAPI 5 in a distributed application environment.
A microphone or some other sound input device to receive the sound is required for speech recognition. In general, the microphone should be a high quality device with noise filters built in. The speech recognition rate is directly related to the quality of the input. The recognition rate will be significantly lower or perhaps even unacceptable with a poor microphone.
Not all sound cards or sound devices are supported by SAPI 5, even if the operating system supports them otherwise.
The following table outlines the RAM usage:

File Name	Approximate File Size	Setup Merge Names
Sapi.dll and Sapisvr.exe	0.5 MB	Sp5.msm
Sapi.cpl	36 KB	Sp5Intl.msm
SR Engine	1.7 MB	Sp5Sr.msm
Command and Control Datafiles	13.4 MB	Sp5CCInt.msm
TTS Engine and voices	7.8 MB	Sp5TTInt.msm
Files common to both Microsoft SAPI 5.1 TTS and SR.	92 KB	SpCommon.Msm
Language-specific SAPI 5.1 inverse text normalization (ITN) components.	108 KB	Sp5itn.Msm

For more information on setup, see the Microsoft Speech SDK Setup 5.1.