application architecture
A logical description of how different components, services, and resources work together to run applications.
Application Compatibility Toolkit
A collection of tools, advice, and methodologies that guides the IT administrator in determining which legacy applications are compatible with Windows 7. It does not make the applications compatible; it just helps the IT administrator use a structured method of testing and tracking compatibility information.
COM
An abbreviation for Component Object Model, which is a generalized method used by some applications to cross-link to and access each other. This is a broader method than OLE.
environment subsystems
Support systems designed for specific types of applications, such as Win32 applications. The environment hides the details of how the application must communicate with lower-level operating system components such as the Executive Services. Environment subsystems operate on a user-mode basis but have awareness of kernel mode services hosted through Executive Services.
Executive Services
A collection of kernel model support modules to manage low-level duties in the operating system such as scheduling processes, managing memory, managing virtual environments, and running core kernel programming.
Hardware Abstraction Layer
Part of the operating system that understands how to talk to the specific computer hardware on which the operating system is installed. This portion of the operating system runs at the lowest level of the application hierarchy in kernel mode.
hives
A discrete body of registry keys and values stored in files as part of the operating system.
kernel
The operating system software that runs in kernel mode on the computer's processor and provides low-level intelligence for the operating system.
kernel mode
An access mode for applications while they are running on the CPU that allows full access to all hardware devices and memory in the computer.
OLE
An abbreviation for Object Linking and Embedding, which is a method used by some applications to cross-link to each other.
registry key
A level in a hive's hierarchy defined by its name and position relative to other keys in the hive hierarchy. A registry key can contain subkeys (other registry keys), values, or both.
Run as administrator
An option to start an application with elevated security privileges.
security identifier (SID)
A coded value assigned to a user account when it is first created to act as a unique identifier that is not duplicated for any other account. The security identifier is unique, regardless of what name is assigned to the user's account.
subkey
A subordinate or lower-level registry key within a hive that can contain values and other subkeys.
thunking
A method where data and parameters passed from 16-bit software to 32-bit software is translated in a bidirectional manner.
user mode
An access mode for applications while they are running on the CPU that allows restricted access to all hardware devices and memory in the computer. This mode makes it difficult for the running application to corrupt and crash the operating system. System-level applications may need more access than is allowed and must use kernel mode instead.
Virtual DOS Machine
A Win32 application that emulates a DOS environment for use by DOS and Win16 applications.
Win16
Applications designed to run in a Windows 16-bit instruction environment.
Win32
Applications designed to run in a Windows 32-bit instruction environment.
Win64
Applications designed to run in a Windows 64-bit instruction environment.
XML
A standard for formatting information in a self-describing way for transfer between different applications.