HEIDENHAIN TNC 426 PB - Load Twos Complement (L-)

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 1111111
(
1
–
1
1
1
5
1
)
0001 0
(
0
+
0
1
0
5
1
)
111
Add the contents of
the word
accumulator and
byte B6.
+ B6 0 ..... 0 0000000
(
0
+
0
5
0
)
00101 0
(
0
+
0
2
1
0
0
)
100
Assign the gating
result to byte B8.
= B8 0 ..... 0 0000000
(
0
+
0
5
0
)
00101 0
(
0
+
0
5
0
)
0101