HEIDENHAIN TNC 426 CB, Technical Manual

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7 – 90 HEIDENHAIN Technical Manual TNC 426, TNC 430
7.7.5 LOAD TWO’S COMPLEMENT (L–)
Syntax: L– (LOAD MINUS)
Operands: B, W, D, K
Action:
Load the two’s complement of the addressed operand, or of a constant, into
the word accumulator. If necessary, the TNC supplements the accumulator
with the correct algebraic sign. The two’s complement allows negative
numbers to be stored, i.e., a number loaded with the L command appears in
the accumulator with an inverted sign. This command can be used only with
word execution.
Example:
Negate the content of byte B5 and then add it to the content of byte B6.
Assign the result to byte B8.
Initial state:
Byte B5
= 15 (dec)
Byte B6 = 20 (dec)
Byte B8 = ?
To aid understanding of this example, the contents of the accumulator and
operands are shown as decimal values in parentheses.
Function STL Accumulator contents [bit] Operand contents [bit]
31..15 ..................... 7 ................. 0 7 ........... 0
Load byte B5 into
the word
accumulator, invert
the algebraic sign. L– B5 1 ..... 1 1 1 1 1 1 1 1
(
1
– 1
1 1
5 1
) 0 0 0 1 0
( 0
+ 0
1 0
5 1
) 1 1 1
Add the contents of
the word
accumulator and
byte B6. + B6 0 ..... 0 0 0 0 0 0 0 0
(
0
+ 0
5 0
) 0 0 1 0 1 0
( 0
+ 0
2 1
0 0
) 1 0 0
Assign the gating
result to byte B8. = B8 0 ..... 0 0 0 0 0 0 0 0
(
0
+ 0
5 0
) 0 0 1 0 1 0
( 0
+ 0
5 0
) 0 1 0 1