Guide to testing non-JTAG devices It is possible to test non-JTAG devices on-board via a JTAG compliant device. This eliminates the need to allow for a separate ISP interface. Atomic Programming Extended Test Language (APEL) software enables you to take full advantage of the power of JTAG, by maximizing test coverage of a board, and programming and testing of non-JTAG devices by utilizing the JTAG scan-chain.