#### 2.1.2.3 Storing operators ¶

The following instructions are the inverse of the load operations: they are used to store a subfield of a register into a memory location. Here, MOD represents the subfield of the memory cell that is to be overwritten with bytes from a register. These bytes are taken beginning by the rightmost side of the register.

`STA` ¶

  Store rA. OPCODE = 24, MOD = fspec. `V <- rA`.

`STX` ¶

  Store rX. OPCODE = 31, MOD = fspec. `V <- rX`.

`STi` ¶

  Store rIi. OPCODE = 24 + i, MOD = fspec. `V <- rIi`.

`STJ` ¶

  Store rJ. OPCODE = 32, MOD = fspec. `V <- rJ`.

`STZ` ¶

  Store zero. OPCODE = 33, MOD = fspec. `V <- 0`.

By way of example, consider the instruction ‘`STA 1200(2:3)`’. It causes the MIX to fetch bytes no. 4 and 5 of register A and copy them to bytes 2 and 3 of memory cell no. 1200 (remember that, for these instructions, MOD specifies a subfield of the memory address). The other bytes of the memory cell retain their values. Thus, if prior to the instruction execution we have

    [1200] = - 20 21 22 23 24
    [rA] = + 01 02 03 04 05

we will end up with

    [1200] = - 20 04 05 23 24
    [rA] = + 01 02 03 04 05

As a second example, ‘`ST2 1000(0)`’ will set the sign of ‘`[1000]`’ to that of ‘`[rI2]`’.