interrupt service routine may be provided from the instruction cache 102 on subsequent interrupt service requests fig3 4 illustrate operation of the instruction cache 102 in accordance with various embodiments fig3 illustrates storage of instructions of an instruction loop 302 in the instruction cache 102 the instruction loop 302 includes instructions stored in the instruction memory 108 starting at instruction 304 through the loop branch instruction 312 the first iteration of the loop 302 is retrieved and executed from the instruction memory 108 in embodiments of the instruction cache 102 that disable writing to the cache blocks 104 after initialization during the first iteration the instructions of the loop are not written to the cache 102 because the lock flags 104 are set to disable writing to the cache blocks 204 at the end of the first iteration the loop branch instruction 312 is identified and the lock flags 104 are reset to enable writing to the cache blocks 204 at the start of the second iteration of the loop 302 as the instructions 304 306 308 and 310 are fetched from instruction memory 108 the instructions 304 310 are stored in the cache blocks 204 and lock flags 104 corresponding to the written cache.