Why can only 256 bytes be moved from one address to another
in a MVC?
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Answer / mike m
THE LENGTH CODE FIELD IS 1 BYTE IN LENGTH.
THE LARGEST VALUE YOU MAY SPECIFY IN A 1 BYTE FIELD IS X'FF'
X'FF' = 255 DECIMAL
THE LEN. IN THE OBJECT CODE FIELD WILL BE 1 LESS THAN
ACTUAL LEN.
| Is This Answer Correct ? | 20 Yes | 1 No |
Answer / vikram
Lenght feild is 8 bits so the data is stored in binary
format so if we have all 8 bits set to 1 then the length
will be 128+64+32+16+8+4+2+1 = 255.or
2^7+ 2^6+2^5...2^0 = 255.
so the lenght is 256 .....
| Is This Answer Correct ? | 3 Yes | 0 No |
Answer / pazhanivel seethapathy
The length of MVC instruction is 1 Byte which is X'FF'. it
can have the range between 0 - 255 so totally 256 bytes of
data can be used.
| Is This Answer Correct ? | 2 Yes | 1 No |
Answer / roocarlin
the length of the MVC instruction itself is 6, one byte for the opcode, one byte for the length of the move-data, 2 bytes for base-displacement of the receiving field, and 2 bytes for the base-displacement of the sending field. since the length field in the MVC instruction is 1 byte, the values can be 0 to 255, thus you would be moving 1 to 256 bytes.
| Is This Answer Correct ? | 2 Yes | 1 No |
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cobol and assembler access
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What is the difference in data type "X" and "P"?
In the house keeping section of an MVS assembly language program, like the one below STM R14,R12,12(R13) BASR R12,R0 USING *,R12,R11 LA R11,2048 LA R11,2048(R11,R12) .... .... 1. What if BASR R12,R0 IS NOT PRECEDE USING *,R12,R11? 2. USING (base address), REGISTER does USING directive says assembler to treat particular Register as a base register with the mentioned base address..in the above case * i.e current location counter..well if that is the case why we need BASR R12,R0 ? 3. What if I write like STM R14,R12,12(R13) BASR R12,R0 LA R11,2048 LA R11,2048(R11,R12) USING *,R12,R11 there is no address resolution being calculated in both LA statements so is it a right way to set Base register?..will there be any issues with Domain regarding R11 and R12?
COBOL 
