IPC@CHIP Documentation - SC12 @CHIP-RTOS V1.10

MEMGAP=Paragraphs
Comments
Sets a memory gap between the loaded DOS programs as a memory reserve.
Some programs compiled with Borland C 5.02 (other compilers??) try to increase their program memory
block at runtime. This can occur, for example, when opening a file with Borland C-library function
fopen, where some additional memory is required. The Borland C-library fopen function calls int 21h
0x4A, which is not directly visible to the application programmer. This memory resize call fails if another
program is loaded after the previous one, because now there is no memory space left for increasing the
memory size of the previously executed program. The program then returns from fopen with an error.
In this case, the global program variable errno is set to value 8 (not enough memory).
To prevent this error, the @CHIP-RTOS allows a memory gap of a defined size between loaded
programs. This memory gap size is specified as a number of paragraphs (where 1 paragraph == 16
Bytes).
This strategy can fail when programs are terminated and restart again.
Example:
[DOSLOADER]
MEMGAP=128
By default, MEMGAP is set to 0. The maximum value is 2048 paragraphs, where any value larger than
this is truncated to 2048
Related Topics
Set memory gap API function
Developer Notes
It is not necessary to set this entry if the application doesn't show the described error. Only if a C-library function
call sets errno to 8, should this value be defined. We recommend in that case a value of 128 paragraphs (2048
Bytes). The described problem was noticed when the Borland C-library function fopen was used. The same
can happen with usage of C-library function malloc using memory model Large. The malloc returns a NULL
pointer in this case.
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BATCH
[BATCH]
BATCHMODE=0/1
Sets the batch file execution mode of DOS programs.
BATCHMODE=0 : (Default mode)
The programs listed in the batch file will be executed concurrently, starting one after
another, without waiting for completion (or going resident) of the predecessor program.
The only exceptions are the WAITand REBOOTcommands.
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