Q38191: P_NOWAIT Is Not Implemented in DOS Version 4.00

Article: Q38191
Product(s): See article
Version(s): 5.00   | 5.10
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | | mspl13_c
Last Modified: 18-NOV-1988

The include file process.h states that P_NOWAIT is enabled in DOS
Version 4.00. This is incorrect. P_NOWAIT is NOT enabled in the
current version of DOS Version 4.00. P_NOWAIT is a modeflag as used in
SPAWNxx functions. P_NOWAIT is used to continue executing the parent
process concurrently with the child process. P_NOWAIT is implemented in
OS/2.

Original DOS Version 4.00 was a multitasking, real-mode only MS-DOS.
The limitations of the real-mode environment made DOS Version 4.00 a
specialized product. Although MS-DOS Version 4.00 supports full preemtive
multitasking, system memory is limited to the 640 kilobytes available
in real mode. This means that all processes have to fit into the
single 640-kilobyte memory area. Because of these restrictions, MS-DOS
Version 4.00 was not intended for general release, but as a platform
for specific OEMs to support extended architectures. Therefore, MS-DOS
Version 4.00 was released as a special OEM product only.

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