Dinesh,
the order of the statements in the script is invalid. Usually, the visual config tool would prevent the generation of such a script but various conversion tools sometimes generate invalid scripts, in case you used any of them. Anyway, to fix your script you have to create heaps at the very beginning of the script instead of later. So, when you move that code to the beginning, your script will start with the following code:
utils.loadPlatform("ti.platforms.evmDM642");
bios.enableRealTimeAnalysis(prog);
bios.enableRtdx(prog);
bios.enableTskManager(prog);
bios.MEM.NOMEMORYHEAPS = 0;
bios.MEM.instance("IRAM").base = 0x00000400;
bios.MEM.instance("IRAM").len = 0x0002fc00;
bios.MEM.instance("IRAM").createHeap = 1;
bios.MEM.instance("IRAM").heapSize = 0x00000000;
bios.MEM.instance("IRAM").enableHeapLabel = 1;
bios.MEM.instance("IRAM").heapLabel = prog.extern("intHeap");
bios.MEM.instance("SDRAM").createHeap = 1;
bios.MEM.instance("SDRAM").heapSize = 0x00000000;
bios.MEM.instance("SDRAM").enableHeapLabel = 1;
bios.MEM.instance("SDRAM").heapLabel = prog.extern("extHeap");
Also, just before you try to change varios LOAD* segments in MEM, you need to enable these changes. So, right before the line
bios.MEM.LOADBIOSSEG = prog.get("SDRAM");
add the line
bios.MEM.ENABLELOADADDR = 1;
That should be enough to make your script valid. The error messages are not very helpful, but because DSP/BIOS is not actively developed I don't think these messages will get any better. Most of the development is done for TI-RTOS (and SYS/BIOS is a part of that product).