When I store data to a cart address does this infact cause the agb to write
to the flash cart or is something else required? (Intel Strata Flash)

i.e. assuming flash block cleared..

mov r0,#0xff ;data to store
mov r1,#0x40 ;Byte write command
mov r2,#0x08000000 ;cart start address
strh r1,[r2] ;write 1/2 word command
strh r0,[r2] ;write data to flash