+--------+-------+-------+---+---+
   | op-code|   I2  | B1| D1| D1| D1|  4 bytes long x'92'
   +--------+-------+-------+---+---+
   0        8       16      24      31
   
        Format:
        MVI   D1(B1),I2

          MVI    AREA,C'A'             /* Move 'A' into AREA        */ 
          MVI    NAME+6,C'B'           /* Move 'A' into name + 6    */ 		  
          MVI    BINARY,X'00'          /* Move x'00' to BINARY      */ 		  		  

Move (MVC) instruction (x'D2')

The MVC instruction is a storage to storage instruction. It is used to copy up to 256 bytes from one place in storage to another. The data in the destination area will be replaced with new new data.

The amount of bytes to be copied is determined by the length of the receiving field. You need to either explicitly define the length or the assembler will determine the destination length at assembly time.

You need to specify the actual amount of data to be moved start to count at 1. Internally the instruction will store this with a value -1. You are moving 256 bytes and they are numbered internally from 0 to 255.

MVC instruction (x'D2')

The MVC character instruction operates by coping the first byte from the sending field to the first byte of the receiving field. This is done left to right.

Instead of having the instruction copy the first byte to the first field in the receiving field you can tell it to copy the first byte to the corresponding byte in the receiving field to the next byte in the receiving field.
This is a easy way to use MVC to clear a field or load it with all the same data.
This diagram will illustrate this process:

These are the instructions used to achieve this task:

          MVI    TEMP(8),SOURCE      /* make a copy of the data      */
          MVC    SOURCE+1(8),TEMP    /* move then one byte down in   */
                                     /* the area                     */

Here is an example to move data up in the data area

This will move one 'A' into the left most position. We then move the next 6 bytes with the 'A' character.

Using the basis on how the MVC instruction functions you can now alter the starting positions to move data forward or backward in a string. Pay special attention because this is destructive and when you are not careful you might overly your data.

Here is an example to move data up in the data area

          MVI    TEMP(8),SOURCE      /* make a copy of the data      */
          MVC    SOURCE+1(8),TEMP    /* move then one byte down in   */ 
                                     /* the area                     */

This example will move data down in the data area. It would move 4 bytes into the data area and start move data from this area for 6 bytes to the the destination.

          MVC    SOURCE(6),SOURCE+4      /* make a copy of the data  */

This diagram demonstrate the data movement.

Move Long (MVCL) instruction (x'0E')

Unlike the MVC instruction the MVCL instruction is a register-to-register instruction. This instruction will use 4 registers in two even-odd register pairs.

The even registers gets loaded with the addresses of the sending and receiving fields. The first operand will contain the receiving address and the second even register will contain the sending field address.

The odd registers contain length values in the the right 3 bytes of the register.

In the sending field pair odd register you can place a fill character in the 4th byte. If the receiving field is longer then the sending field this character will be used to pad the field on the right.

The instruction will add 1 to the address to copy the next byte too and subtract 1 from the length value after every successful copy.

As in the MVC instruction the copy is done from left to right. Overlap is not allowed in the MVCL instruction. If this happens the condition code will be set to 3 and no movement will happen.

The maximum amount of data that can be copied with this instruction is 16 megabytes as the length indicator is the right 3 bytes of the odd register values.

In addition to copying the data this instruction will also set a condition code as shown in below.

  Binary
  in storage
  COMP

  Binary 
  in register
  COMP

  Packed
  COMP-3

  Numeric
  Character