Function:

Stores bit field data from AX into memory. Bit field length is specified by
the lowest four bits of the second operand. ES:DI specify the first memory
location to write, and the low 4-bits of the first operand specify the bit
offset position. The bit field can cross a byte boundary. After each
complete data transfer, DI and the first operand are automatically updated
to point to the next bit field.

This mnemonic (INS) conflicts with the Intel mnemonic INS, which reads
a string from an I/O port. This Intel instruction has bugs which are listed
with the entry for <INS>. For clarity, this NEC version is referred to as
"NECINS" where possible in this list.

Note that 0F is treated as <POP CS> on the 88/86 and prefixes newer
instructions on 286+ CPUs.

(Supplied by Anthony Naggs)