SROMCLKOFF
csr ^= SROMCLKOFF; EMIT; /* clock low; data not valid */
csr ^= SROMCLKOFF; EMIT;
csr ^= SROMCLKOFF; EMIT; /* clock low; data not valid */
csr ^= SROMCLKOFF; EMIT;
csr ^= SROMCLKOFF; EMIT; /* clock low; data not valid */