how can i get sh-elf-gcc

sh-elf-gcc -ml -Wl,-Ttext,0x8c010000 -nostartfiles -nostdlib -e _start prog.c -o prog.elf -lgcc
sh-elf-objcopy -O binary prog.elf prog.bin
scramble prog.bin 1ST_READ.BIN



http://mc.pp.se/dc/ip.bin.html

It depends on what OS you're on, but if you're using Linux or Windows the following links should get you want you want:

http://consolevision.com/?Dreamcast:...:Under_Windows
http://consolevision.com/?Dreamcast:...nt:Under_Linux