IBM s/390 manual Flex-Es, Brief introduction

3.1 FLEX-ES

This redbook concentrates on the use of FLEX-ES with a ThinkPad running Linux. Furthermore, we describe a particular ThinkPad/EFS configuration used as a starting point for IBM’s S/390 Partners in Development (PID) organization. This configuration might be regarded as the minimum practical system for using OS/390 and z/OS.

The following descriptions and figures assume this particular ThinkPad/EFS configuration. Other configurations and more complex systems are possible, but are not described here.

3.1.1 Brief introduction

Conceptually, FLEX-ES can be viewed as the following components:

￿A S/390 instruction emulator, which might be seen as the heart of the system. It examines each S/390 operation code and emulates that operation, using the instructions of its underlying PC processor.

￿A resource manager that controls the interfaces between the emulated S/390 processors and emulated I/O devices and connections.

￿Emulators for various S/390 I/O devices.

￿A FLEX-ES console for controlling FLEX-ES startup and operation. (This is not related to the OS/390 master console.)

￿A Terminal Solicitor program that emulates local, channel-attached, non-SNA 3270 terminals. The actual terminals are TN3270 sessions that connect to this program through normal TCP/IP protocols.

￿A number of utility programs to help set up and run the FLEX-ES environment.

Figure 3-1provides a simplified view of FLEX-ES operation. FLEX-ES is simply a process1 under Linux. While this illustration should not be taken too literally, it can be used to make a number of basic points about FLEX-ES.

1It is actually a number of interrelated processes and threads, but that can be ignored at the conceptual level.

16S/390 PID: ThinkPad Enabled for S/390