Hello,
to start with your (custom) board I would recommend to use a Build Environment for a ST board which also uses a parallel screen interface, for example the STM32F746 Discovery. At the end of the linked article you can find under 'Custom specific hardware' what you have to do to adapt this Build Environment to another board.
Of course, it is possible to use just internal RAM if this is big enough for the frame buffer and memory pool. To configure the frame buffer and memory pool address you need to adapt the defines in ewmain.c only. With these defines the Embedded Wizard memory manager gets the address information where the framebuffer and memory pool is located. By help of the memory map of your microcontroller, you will get the address of the internal RAM. this Address is what you have insert to avoid using the external SDRAM. See here the lines from ewmain.c to do this work:
/* loacate framebuffer at the beginning of first SDRAM bank */
#define FRAME_BUFFER_ADDR (void*)(SDRAM_DEVICE_ADDR)
#define FRAME_BUFFER_SIZE FRAME_BUFFER_WIDTH * FRAME_BUFFER_HEIGHT * FRAME_BUFFER_DEPTH
#ifdef EW_USE_DOUBLE_BUFFER
/* locate double-buffer at the end of the last SDRAM bank - this ensures
that front/back-buffer are located within different banks of the SDRAM */
#define DOUBLE_BUFFER_ADDR (void*)(SDRAM_DEVICE_ADDR + SDRAM_DEVICE_SIZE - FRAME_BUFFER_SIZE)
#define DOUBLE_BUFFER_SIZE FRAME_BUFFER_SIZE
#else
#define DOUBLE_BUFFER_ADDR (void*)(0)
#define DOUBLE_BUFFER_SIZE 0
#define NUMBER_OF_FIELDS 3
#endif
/* use remaining SDRAM area for memory pool */
#define MEMORY_POOL_ADDR (void*)(SDRAM_DEVICE_ADDR + FRAME_BUFFER_SIZE)
#define MEMORY_POOL_SIZE SDRAM_DEVICE_SIZE - FRAME_BUFFER_SIZE - DOUBLE_BUFFER_SIZE
You can see that that 'SDRAM_DEVICE_ADDR' itself is also a define from the BSP of this board. Just enter here another valid address of any RAM area.
In each project (GCC, TrueSTUDIO, etc.) is a global define (EW_USE_DOUBLE_BUFFER) to disable the double buffering mode. You said that your board has "a lot of internal RAM ", if your board has enough free RAM for double buffering there is no need to switch to single buffering.
The precompiled libraries that are in use for our free version do not have any dependencies to the external SDRAM/RAM respectively the address of the frame buffer and memory pool. All the necessary files to configure are just inside the "TargetSpecific' folder (and in your case the main.c).
If you have more question, feel free to ask again.
Kind regards
Tim