And even with a 64-bit machine, running the 32-bit version of TurboCAD on it will still have the same memory limitations.
However, there is a possible workaround for a bit extra memory.
While I haven't done this myself, you could add more RAM (totaling 6-8 GB) to your 32-bit machine, then assign a RAMDisk to use the extra memory above 4 GB.
BE VERY CAREFUL THAT THE RAMDISK SOFTWARE YOU CHOOSE SUPPORTS OPERATION ON A 32-BIT MACHINE WITH MORE THAN 4 GB TOTAL RAM.
Once that is done, modifying your bootup to use the RAMDisk for system memory (instead of regular RAM in the bottom ) will free up a few hundred megabytes.
Here's a link to one source: http://memory.dataram.com/products-and-services/software/ramdisk
. One of the versions is free.
This link promises access to memory when you've got a 32-bit system with more than 4 GB of RAM: http://www.romexsoftware.com/en-us/primo-ramdisk/index.html
To be blunt, you are better off going to a 64-bit machine, but if budget is a concern, adding RAM and a RAMDisk utility will provide some relief.
TC Pro Platinum 2020, 2019, 2018, 2017, 2016 & 2015 (all with LightWorks & RedSDK) & V21
System: i7-5820K @ 3.30GHz, ASRock X99 Extreme4, 16GB DDR4-2133 RAM, Gigabyte GTX 970, Samsung NVMe SSD 950 (256GB), Windows 7 Pro (64-bit) SP1