gtpm1m45TPF V4R1 Migration Guide: 3.1 to 4.1

Changes to E-Type Programs

All ECB-controlled (E-type) programs run in the ECB virtual memory (EVM), which consists of private and shared storage. There is private storage in two areas:

Private storage cannot be shared between ECBs. ECBs can share storage in common blocks and other areas of the EVM. Shared storage consists of common blocks and the remainder of of the EVM that maps directly to the virtual memory of an I-stream (also known as system virtual memory (SVM)). See Figure 6 for more information.

In the TPF 4.1 system, all programs are 4 KB in size. ECBs are now 12 KB and are comprised of three sections:

There are significant changes to the allocation of E-type programs, which are described in Allocating Programs, Transfer Vectors, and Pools. These changes include specifying 24- or 31-bit operating mode, authorization privileges, and residency. Any application programs that access the system tables, which have moved above the 16 MB, must be allocated to run in 31-bit mode. If you issue a MODEC macro to switch to 24-bit mode from one of these programs, you will get unpredictable results. All IBM C language programs must be allocated in 31-bit mode.

Other changes that you need to be aware of include:

Despite all these changes, many application programs that do not share data and are reentrant can be used in the TPF 4.1 system without change.

The following sections describe: